US3686917A

US3686917A - Roll forming apparatus

Info

Publication number: US3686917A
Application number: US131683A
Authority: US
Inventors: Ryotaro Hikida; Taikichi Awano; Atsushi Danno; Yoshiro Kojima
Original assignee: Toyota Auto Body Co Ltd; Toyota Central R&D Labs Inc
Current assignee: Toyota Auto Body Co Ltd; Toyota Central R&D Labs Inc
Priority date: 1971-04-06
Filing date: 1971-04-06
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29

Abstract

A roll forming apparatus for impressing upon a plate corrugation of finite length. Spaced longitudinally a predetermined distance are two synchronously operated roll couples for preliminary and finish forming. Each roll couple has complementary, circumferentially discontinuous, ribs and grooves spaced axially thereof.

Description

United States Patent Hikida et al.

[ 1. Aug. 29, 1972 [54] ROLL FORMING APPARATUS [72] Inventors: Ryotaro Hikida, Taikichi Awano, Atsushi Danno, Yoshiro Kojima, all

fNasexeJaw V, .7

[73] Assignee: Kabuskiki Kaisha Toyoto chuo Kenkyusho and Toyota Shatai Kabushiki Kaivsha, both of Nagoya,

Japan [22] Filed: April 6, 1971 [21] Appl. No.: 131,683

[52] US. Cl. ..72/187, 72/196, 72/180 [51] Int. Cl. ..B2ld 5/16 [58] Field of Search ..72/187, 196, 180

[56] References Cited UNITED STATES PATENTS 2,370,702 3/1945 Yoder ..72/ 196 2,327,844 8/1943 Johnston ..72/196 X 838,568 12/1906 Numan ..72/196 X 1,211,460 l/l9l7 Lindquist ......72/l96 Primary ExaminerMilton S. Mehr Att0rney-ClariO Ceccon [57] ABSTRACT.

A roll forming apparatus for impressing upon'a plate corrugation of finite length. Spaced longitudinally a predetermined distance are two synchronously operated roll couples for preliminary and finish forming. Each roll couple has complementary, circumferentially discontinuous, ribs and grooves spaced axially thereof.

1 Claim, 13 Drawing Figures mimimucee 1912 3.686317 SHEET 3 0F 8 INVENTORS BY mv 7f PATENTEMsze m2 SHEET 5 OF 3 YFIG.8

BY 54 g, 6001 PKTENFEDmsze m2 SHEET 6 (IF 8 sea.

m9 QR N9 ROLL FORMING APPARATUS The invention relates to a roll forming apparatus for continuously forming a plate member into a shaped plate having a plurality of bulged projections therein spaced apart at a given interval crosswise of the member and which are of a small width crosswise and have a finite required length longitudinally.

The prior art formation of such bulged projections commonly relies on the combination. of a multiple stage roll forming machine and a press wherein the multiple stage roll forming machine comprises rolls having annular projections and recessed grooves formed therein which cooperate each other to form corrugations crosswise of the plate member, followed by crushing operation of the press applied to a part of the corrugations in a manner to form flat portions spaced apart from each other by a given interval lengthwise of the member. Alternatively, the forming rolls may comprise a roll having a plurality of arcuate forming pieces fitted therearound which can be hydraulically operated to move diametrically, and another roll having recessed grooves corresponding to the arcuate forming pieces, so that upon meshing engagement of the both rolls, a hydraulic control may be operated to advance or withdraw the arcuate forming pieces to form bulged projections in a plate member which have a length equal to the full length of the respective arcuate forming pieces.

However, the above described prior art failed to provide satisfactory results. That, with the former approach, corrugations once formed must be crushed to a flat plate form, and this not only rendered it possible to achieve a shaped plate of good form, but also prevented a continuous forming operation. On the other hand, the latter approach requires a control device controlling the amount of indentation performed by the arcuate forming piece, which results in a complexity and high cost of the forming apparatus, and also involves additional disadvantage of causing a significant local reduction in the thickness of the shaped plate where an increased number of bulged projections are to be formed.

The invention aims to overcome the above disadvantages of the prior art, by providing an apparatus which is relatively simple in construction and operation. The apparatus comprises first and second forming stands located at a given spacing therebetween, and synchronizing means which acts to operate the forming roll of the second stand in synchronism with the forming roll of the first stand. The first forming stand embosses a plurality of bulged projections in a plate member, spaced apart crosswise of the plate member at a given spacing, the embossed projections being of a narrow width crosswise and of a required finite length longitudinally and being close to the configuration of the bulged projections of a desired or finished shaped plate. Thus, for example, where the desired shaped plate has bulged projections formed by the first forming stand have round corners in section. Such forming operation will be referred to hereinafter as a preliminary forming operation. The second forming stand operates to form the corners of the bulged projections into a square or other desired form (such forming operation will be referred to hereinafter as finish forming operation). In this manner, the invention enables a continuous formation of a shaped plate to size which is excellent in its form and appearance, with little strain and bending and minimized local reduction of plate thickness.

For a better understanding of the invention, embodiments thereof will be described below with reference to the drawings, in which:

FIG. 1 is a perspective view of a whole shaped plate formed with the apparatus according to an embodiment of the invention,

FIG. 2 is a cross-section along the line II-II shown in FIG. 1,

FIG. 3 is a top view of the apparatus with part removed,

FIG. 4 is a front view, partly cut away, of a first forming stand,

FIG. 5 is a side elevation of FIG. 4,

FIG. 6 is a front view of the forming rolls in the first forming stand,

FIG. 7 is a front view of the forming rolls of a second forming stand,

FIG. 8 is an electrical circuit diagram of a synchronization device of the present embodiment,

FIG. 9 illustrates the operation of the apparatus,

FIGS. 10 and 11 are front views showing modified forming rolls in the first and second forming stands,

FIG. 12 is a front view of guide rollers showing a modification of a guide plate located at the outlet of the second forming stand, and

FIG. 13 shows a lay-out of guide rollers.

Referring first to FIGS. 3 to 9 inclusively, an embodiment of the invention will be described.

Reference character A represents a first forming stand for preliminary forming operation which comprises a pair of forming rolls oppositely disposed at a given spacing, and reference character B represents a second form stand for finish forming operation which also comprises another pair of opposite disposed forming rolls.

Referring to FIGS. 4 and 5 which show the first forming stand A, there are provided a pair of frame members 1, 1 which are vertically mounted at their bottom on a base 2 with their

central notches

10 and 10 aligned. A stay 11 extends across the top ends of the frame members 1, 1' and are secured thereto. A lower forming roll 4 is rotatably joumalled in a pair of bearings 12 and 12' located in the bottom part of the central notches of the respective frame members, these bearings being secured against movement in the axial direction of the roll as well as vertically of the frame members. Another pair of

bearings

13 and 13' for rotatably receiving an upper forming roll 3 are fitted in the top part of the central notch of the respective frame members, and a pair of springs 14 and 14' are interposed between the both pairs of bearings l2, l2 and 13, 13' to urge the

bearings

13 and 13' in an upward direction, which is counteracted by a downward pressure from the lower ends of screw-down devices 15 and 15' so as to prevent the

bearings

13 and 13' from movement in the axial direction of the upper forming roll 3.

At the top of the frame members, screw-down devices 15 and 15' threadably engage with the frame members 1, 1' and stay 11 and carry integrally connected gears 16 and 16', respectively, which are positioned in meshing engagement with a gear 18 that is secured on a handle member 17 rotatably mounted on the stay 11 substantially at the center thereof. The arrangement is such that rotation of the handle 17 causes rotation of the screw-down devices and 15' to produce a vertical movement thereof by virtue of their threadable engagement with the frame top, thereby moving the

bearings

13 and 13' to a desired position in which they are to be securedly supported.

The upper and lower forming rolls 3 and 4 are journalled so that they lie horizontally with their centers lying in a common plane perpendicular to the base 2. One end of each of the upper and lower forming rolls 3 and 4 is connected with a gearing device 20 through a universal joint -19 or 19, respectively. The gearing device 22 is adapted to reduce the speed of rotation of the rotary motion transmitted from an electric motor 22 coupled thereto by means of a flexible joint 21, and to transform such motion into two rotary drives of opposite rotating directions so as to drive the upper and lower forming rolls 3 and 4 at the same but opposite peripheral speeds. An eccentric cam 25 of substantially elliptical form is integrally keyed to the other end of the lower forming roll 4 so as to operate, at a selected angular position thereof, a normally open limit switch 26 secured to the bottom side wall of the frame member 1.

Referring to FIG. 6, the peripheral surface of the lower forming roll 4 is formed with a unit comprising a shaped

surface including projections

41, 41 for use in the preliminary forming operation and a flat surface 42 other than the shaped surface. Thus the cylindrical surface of the lower forming roll 4 is formed with preliminary forming

projections

41, 41 extending in a flow direction perpendicular to the axis of the roll and along the cylindrical surface 40. These

projections

41, 41 are arranged in parallel relationship and equally spaced apart from each other, and the number of such projections corresponds to the number of desired bulged projections 703 to be formed on a shaped plate 700 (refer to FIGS. 1 and 3). Each of the

projections

41, 41 is identical in shape and size, so that description of one of the projections 41 will be sufficient. The height of the projection 41, as considered in axial section, is made substantially equal to the height of the profile of bulged projections 703 of the shaped plate (refer h shown in FIG. 2), and the profile of the projection 41 is in the form of a semi-circular, arcuate projection in which the corners are more smoothly curved than the corners 701 in the bulged projections 703 of the shaped plate 700. The circumferential length of the projection 41 does not extend all around the circumference of the lower former roll 4, but is of an interrupted annular form along the cylindrical surface 40 having a starting end s and a terminating and f Intermediate the starting and terminating ends, the cylindrical surface 40 is quite free from projections or recesses, thus leaving the flat surface 42. The circumferential length of the flat surface 42 is made equal to the lengthwise dimension of a flat portion 702 between the bulged projections 703 of successive shaped plates 700.

Where the projection 41 starts or ends adjacent the ends s, and f the projection 41 has a gentlely inclined surface 41 1, the angle of inclination of which is close to but slightly less than that of an inclined surface 704 provided at the longitudinal ends of a bulged projection 703 on the shaped plate 700.

Adjacent the opposite axial ends, the cylindrical surface 40 of the roll is provided with a pair of

guide projections

43 and 43 which extend the full circumference of the cylindrical surface 40 in an annular manner and in parallel relationship with the axially spaced

projections

41, 41 for preliminary forming use.

The upper forming roll 3 is shaped to interengage the lower forming roll 4 to effect a preliminary forming of a plate member 710, and at this end is provided with a unit comprising a shaped

surface including grooves

31, 31 to be used in the preliminary forming step and a flat surface 32 other than the shaped surface. Specifically, the cylindrical surface 30 of the upper forming roll 3 is formed with

grooves

31, 31 for preliminary forming use which extend radially inwardly from the cylindrical surface 30 at positions corresponding to the positions of the

projections

41, 41 of the lower forming roll 4. The

grooves

31, 31 each have a flat bottom surface, and have a depth greater than the height of the projections 41 so that upon engagement with the projections 41 of the lower forming roll 4, they provide a relief to the material of the plate member 710. The circumferential length of the grooves 31 is made equal to the circumferential length of the projections 41 of the lower forming roll 4, and thus they are of an interrupted annular form having a starting end s and a terminating end f,'. The cylindrical surface 30 has a flat surface 32 similar to the flat surface 42 on the lower forming roll at position corresponding to the latter.

The comers 301 of the cylindrical surface 30 adjoining the grooves 31 are shaped in a smooth arcuate form.

Adjacent the axial opposite ends, the cylindrical surface 30 is formed with a pair of guide grooves 33 and 33' which receive the guide projections 43 and 43' of the lower forming roll 4.

The cylindrical surface 30 of the upper former roll 3 has a diameter, indicated by D which is equal to the diameter, D of the cylindrical surface 40 of the lower forming roll 4.

The second forming stand B has a forming roll mount and a roll bite gap adjusting device similar to those associated with the first forming stand which have been described above with reference to FIGS. 4 and 5, and which therefore will not be described in detail again.

However, the second forming stand B includes forming rolls and drive which are different in shape and arrangement from those provided in the first forming stand. Referring to FIG. 7 which show forming rolls, a

lower forming roll 6 is formed with at least one unit comprising a shaped surface including finish-forming

projections

61, 61 and a flat surface 62 other than the shaped surface. Thus the cylindrical surface of the lower forming roll 6 is formed with

parallel projections

61, 61 for finish forming, in a manner corresponding to the

projections

41, 42 provided on the lower forming roll 4 in the first forming stand. These

projections

61, 61 are adapted to interengage with

grooves

51, 51 in an upper forming roll 5 (to be described later) to provide a finish forming in to a desired shape of shaped plate 700 (refer FIGS. 1 and 2) for a preliminarily shaped plate 700a formed by the first forming stand A. The projection 61 has a height which is equal to the height (shown at h in FIG. 2) of a bulged projection on the desired shaped plate 700. In axial section, the projection 61 has a shallow groove 61 1 formed centrally in its outer periphery, and has opposite corners 612 which are of an arcuate form having a small radius of curvature which is equal to the radius of curvature in the corners 701 of the bulged projection 703 of a desired shaped plate 700 as the latter comers are viewed in lateral cross-section. The length of the projection 61 in the circumferential direction is equal to the circumferential length of the projection 41 of the lower forming roll 4 in the first forming stand A, and thus does not extend all around the lower forming roll 6 and is of an interrupted annular form having a starting end s; and a terminating end f The lower forming roll is formed with a flat surface 62 in the similar manner as in the first forming stand A. However, by virtue of the diameters D and D of the rolls in the second forming stand B which are chosen slightly less than the diameters D and D of the rolls in the first forming stand A for the reason to be described later, the flat surface 62 has a circumferential length which is slightly less than the circumferential lengths of the

flat surfaces

32, 42 of the cylindrical roll surfaces 30, 40 in the first forming stand A. The flat surface 62 is centrally formed with an axially extending groove 621 for the full width of the lower forming roll 6, and when such groove 621 is positioned opposite to a groove 521 formed in the flat surface 52 of the upper forming roll 5 as will be described later, there is produced a spacing in excess of the thickness of a plate member 710 between the upper and lower forming

rolls

5 and 6. The projection 61 has inclined surfaces 613 adjacent the starting terminating ends s and f which extend to the top of the projection 61 with an angle of inclination that is equal to that of an inclined surface 704 at either longitudinal end of a bulged projection 703 of a desired shaped plate 700.

Adjacent the opposite axial ends the cylindrical surface 60 has a pair of

guide projections

63 and 63 formed thereon which correspond to the annular guide projections 43 and 43' on the lower forming roll 4 of the first forming stand A and are of an interrupted annular form.

The upper forming roll 5 is shaped to cooperate with the lower forming roll'6 to provide a finish forming of a preliminarily shaped plate 710a formed by the first forming stand A, and is formed on its periphery with at least one unitcomprising a shaped

surface including grooves

51, 51 for finish forming and a flat surface 52 other than the shaped surface. Thus the cylindrical roll surface 50 of the upper forming roll 5 is formed with parallel running

grooves

51, 51 for finish forming, at positions corresponding to the projections 61 on the lower forming roll 6. The depth to the bottom surface of the groove 51 is made greater than the height of the projection 61 on the lower forming roll 6, and such bottom surface of the groove 51 is centrally formed with a small projection 511 which corresponds to the shallow groove 611 formed in the projection 61 of the lower forming roll 6. The small projection 511 in the groove 52 has such a height that it does not reach the level of the cylindrical roll surface 50 and the depth as measured from this roll surface to the projection 511 is equal to the height of the projection 61 on the lower forming roll 6 as measured from the cylindrical roll surface 60. The

grooves

52, 52 does not extend completely around the periphery of the upper forming roll 5, but has a circumferential length which is equal to that of the

projections

61, 61 on the lower forming roll 6 and thus has a starting end s and a terminating end f Opposite to the flat surface 62 on the lower forming roll 6, the cylindrical surface 50 has a similar flat surface 52, in which a groove 521 extends centrally.

Adjacent the opposite axial ends, the cylindrical roll surface 50 has a pair of guide grooves 53 and 53' formed therein at positions corresponding to the guide projections 63 and153 on the lower forming roll 6.

The diameter of the cylindrical roll surface 50 of the upper forming roll 5 in the second forming stand B, or roll diameter D is made equal to the diameter of the cylindrical roll surface 60 of the lower forming roll 6 or roll diameter D However, to facilitate synchronization to be described later, the roll diameters D and D off the upper and lower forming

rolls

5 and 6 in the second forming stand B are made slightly less than the roll diameters D, and D of the upper and lower forming rolls 3 and 4 in the first forming stand A, as mentioned previously.

Referring to FIG. 3, the drive for the second forming stand B comprises a gearing device 20 and an electric motor 22 with an electromagnetic clutch and brake 23 and a flexible joint 24 connected therebetween. The rotary drive from the motor 22 being transmitted to the upper and lower forming

rolls

5, 6 through flexible joint 24, electromagnetic clutch and brake 23, flexible joint 21, gearing device 20 and universal joints 19, 19'.

An eccentric cam 27 of substantially elliptical form is integrally keyed to the end of the shaft of the lower forming roll 6 remote from the end which is coupled with a flexible joint 19', the cam 27 being operable to operate a normally closed limit switch 28 (refer FIG. 9) at a particular angular position thereof, the switch 28 being secured to the bottom side wall of the frame member 1'. The electromagnetic clutch and brake 23 is operated by the normally closed limit switch 28 in the second forming stand B and by the normally open limit switch 26 in the first forming stand A for stopping and starting the forming rolls in the second forming stand.

FIG. 8 shows an electrical circuit diagram of the circuit including the electromagnetic clutch and brake 23 and the both

limit switches

26 and 28 which is used in the apparatus of the present embodiment. An a.c. source'is connected across a pair of terminals 0 and b. A circuit 7 directly connected with the terminals a and b includes an electromagnetic solenoid for an electromagnetic relay 8 and a parallel connection of the normally open limit switch 26 of the first forming stand A and the normally closed limit switch 28 of the second forming stand B. A step-down transformer 91 coupled across the supply terminals has its secondary winding connected with a circuit 9 including a rectifier 92, the circuit 9 including a normally open contact 81 of the electromagnetic relay 8 connected in series with a clutch coil 231 of the electromagnetic clutch and brake 23 and also including in parallel circuit relationship therewith a normally closed contact 82 of the electromagnetic relay 8 connected in series with a brake coil 232 of the electromagnetic clutch and brake 23. Clutch and

brake coils

231 and 232 are shunted by

discharge resistors

233 and 234, respectively, which serve the suppression of the occurrence of a high induction voltage across these coils upon interrupting the current flow therethrough.

The first and second forming stands A and B thus constructed are arranged so that a plane including the axes of the respective forming rolls in the first forming stand A is parallel to a plane including the axes of the respective forming rolls in the second forming stand, with a spacing therebetween being chosen to be an integral multiple of the circumferential length of the unit comprising the grooves 31 and flat surface 32 of the upper forming roll 3 of the first forming stand A (or the unit comprising the projections 41 and flat surface 43 of the lower forming roll 4). The forming rolls in the first and second forming stands A and B are driven for rotation at such a rate that the peripheral speed of the respective cylindrical roll surfaces is identical and in a direction to feed a plate member 710 from the inlet side to the outlet side (such direction being indicated by an arrow in FIG. 3).

Referring to FIGS. 3 and 9,

numerals

101, 101', 102,.

102' and 103, 103', 104, 104 denote guide plates disposed at the inlet and outlet sides of the first and second forming stands, respectively, for providing smoothness in the roll forming operation.

Referring to FIG. 9, the operation of the apparatus according to the embodiment described above will be described. The apparatus is designed to form a plate member 710 continuously into a shaped plate 700 which has a plurality of bulged projections 703 formed thereon at a given interval crosswise which have a required finite length longitudinally, a narrow width crosswise and angular corners 701. Before initiating a forming operation, the spacing between the upper and lower forming rolls of the respective forming stands is previously adjusted to a suitable valve equal to the thickness of a plate member 710 by the use of the handle 17 (see FIGS. 4 and 5), and then the forming rolls are set in rotating motion by the associated drive means. As a result, the upper and lower forming rolls 3 and 4 of the first forming stand A are rotated at the same but opposite peripheral speed of the cylindrical roll surface (as indicated by arrows designated by E in FIG. 9), and the upper and lower forming

rolls

5 and 6 of the second forming stand B are also driven in the opposite directions (indicated by arrows designated by F in FIG. 9) at the same peripheral speed of the cylindrical roll surface as that of the rolls 3 and 4 of the first forming stand A.

As a plate member 710 is forced, between the

guide plates

101 and 101 provided at the inlet side of the first forming stand A, in the direction indicated by an arrow C (FIG. 9), the plate member 710 is forced into the gap between the interengaging upper and lower forming rolls 3 and 4 of the first forming stand A which rotate at the same speed in the opposite directions, whereby it is fed from the inlet side to the outlet side by virtue of the rotation of the both rolls 3 and 4.

During such passage, the first forming stand A acts, by the intermeshing engagement of the groove 31 in the upper forming roll 3 and the projection 41 in the lower forming roll 4, both of which are of the form to provide the preliminary forming, to form a plate member 710 into a preliminary shaped plate 710a which, as shown in section between the upper and lower forming rolls 3 and 4 in FIG. 6, has a form nearly close to that of a desired shaped plate. Thus the preliminary shaped plate 710a has a plurality of bulged projections 713a embossed thereon with a given interval crosswise, each of which has a narrow width crosswise and a required finite length longitudinally, with its profile having smoothly arcuate corners 711a which are not formed angular as in the desired shaped plate 700 and with its inclined surfaces 714a at the longitudinal ends thereof being less sharply inclined than the inclined surfaces 704 on the desired shaped plate 700. Where the upper and lower forming rolls 3 and 4 assume such relative position as to present the

flat surfaces

32 and 42, which are free from grooves 31 and projections 41, respectively, opposite to each other, they merely apply urging pressure to the plate member 710 in a sandwiching manner, without applying any deforming stresses, thus leaving a flat portion 712a. The engagement between the

guide grooves

33, 33 located adjacent the opposite axial ends of the cylindrical roll surface 30 and the

guide projections

43, 43 located adjacent the opposite axial ends of the cylindrical roll surfaces 40 serves to grip the plate member 710 firmly adjacent the crosswise edges thereof to form a longitudinally continuous belt-like projection 715 and 715' (see FIG. 6) therealong, thereby rendering the forming applied to the bulged projections 713a to be that of a plastic deformation and also preventing the occurrence of wrinkles due to simultaneous forming.

As a result, after passing through the first forming stand A, the preliminary shaped plate 710a is formed with a plurality of bulged projections 713a spaced apart at a given interval crosswise and each of which has a narrow width crosswise and a required finite length longitudinally, the projection 713a having a profile such that its corners 711a are of gently arcuate form rather than being angular as in the bulged projection 703 of a desired shaped plate 700. In addition, the preliminary shaped plate 710a is also formed with belt-

like projections

715 and 715 which extend continuously in the longitudinal direction along the opposite lateral edges thereof.

The preliminary shaped plate 710a from the first forming stand A isfed in the direction indicated by arrow B in FIG. 9 towards the second forming stand B by the rotation of the forming rolls 3 and 4, while passing between the

guide plates

102 and 102, and between the

guide plates

103 and 103 into the gap between the upper and lower forming

rolls

5 and 6 of the second forming stand B to be fed from the inlet side to the outlet side thereof by virtue of the rotation of the upper and lower forming

rolls

5 and 6.

The second forming stand B adequately positions the preliminary shaped plate 710a in the crosswise direction by engagement of the

guide grooves

53 and 53 in the upper forming roll 5 and the

guide projections

63 and 63 on the lower forming roll 6 with the belt-like projections 715 and 715' which have been formed adjacent the opposite lateral edges of the preliminary shaped plate 710a by the preliminary forming operation in the first forming stand A. The finishforming grooves 51 in the upper forming roll 5 and the finish-forming projections 61 on the lower forming roll 6 form by their interengagement the preliminary shaped plate 710a which now has a configuration substantially close to that of a desired shaped plate 700 into a shaped plate 710 having the profile as indicated in FIG. 7 and which corresponds to a desired shaped plate 700 with belt-

like projections

715 and 715 formed adjacent the opposite lateral edges thereof. Specifically, in the second forming stand B, the inclined surfaces 613 of the finish-forming projections 61 on the lower forming roll 6 therein form the inclined surfaces 714a at the longitudinal ends of the pre-formed bulged projections 713a and having a relatively small angle of inclination into inclined surfaces 714b having an more sharp angle of inclination which is equal to that of the inclined surfaces 704 at the ends of the bulged projections 703 on the desired shaped plate 700. In addition, the interengagement of the finish-forming grooves 51 in the upper forming roll with the finish-forming projections 61 on the lower forming roll 6 causes the small projections 611 provided centrally in the bottom wall of the finish-forming grooves 51 to abut against the top of the bulged projections 713a which is pre-formed in the first forming stand A to be gently arcuate in section, so as to cooperate with the oppositely positioned shallow grooves 611, provided centrally in the outer periphery of the finish-forming projections 61 of the lower forming roll 6, to urge downwardly and flatten such top. At the same time, the respective corners 612, formed with a small radius of curvature, of the finishforming projections 61 on the lower forming roll 6 urges the corners 711a of the bulged projections 713a upwardly in a direction opposite to the downward pressure acted by the projections 511, thereby achieving angular corners 71111 in the bulged projections 713b in the same configuration as those in the bulged projections 703 of the desired shaped plate 700. Where the flat surface 52 of the upper forming roll 5 and the flat surface 62 of the lower forming roll 6 come opposite to each other, they merelymove against the flat portion 712a of the preliminary shaped plate 710a. When the groove 521 and groove 621, formed centrally in the

flat surfaces

52 and 62, respectively, move into opposite positions, the spacing between these flat surfaces becomes in excess of the thickness of the plate member 700, so that no deforming stress is applied to the latter, which therefore is delivered with flat portion 7l2b.

In this manner, the first forming stand A pre-forms the plate member 710 into a preliminary shaped plate 7100, which is finish-formed into a shaped plate 710b in the second forming stand B. In order to obtain a well formed shaped plate 700, it is necessary to ensure that the interengagement between the finish-forming

grooves

51, 51 in the upper forming roll 5 and the finish-forming

projections

61, 61 on the lower forming roll 6 of the second forming stand B be in full coincidence with the bulged projections 713a on the preliminary shaped plate 710a as it is fed into the second forming stand after having been pre-formed by the interengagement between the

pre-forming grooves

31, 31 in the upper forming roll 3 and the

pre-forming projections

41, 41 on the lower forming roll of the first forming stand A.

The above full coincidence can be achieved by first choosing the spacing between a plane which includes the axes of the both forming rolls of the first forming stand A and another plane which includes the axes of the both forming rolls ofthe second forming stand to be an integral multiple of the circumferential length of one unit on the upper forming roll 3 of the first forming stand A which comprises the pre-forming grooves 31 and the flat surface 32, and secondly, by causing the position in time at which the starting end s, of the preforming

grooves

31, 31 in the upper forming roll 3 of the first forming stand A interengage with the starting end s, of the

pre-forming projections

41, 41 on the lower forming roll 4 in a plane which includes the axes of the both forming rolls, to bite in the plate member 710, to be coincident with the position in time at which in the second forming stand B, the starting end s of the finish-forming

grooves

51, 51 in the upper forming roll 5 intergage with the starting end s of the finish-forming

projections

61, 61 on the lower forming roll 6 in a plane which includes the axes of both of these forming rolls to thereby bite in the preliminary shaped plate 710a.

Depending upon the material of plate member 710, an elongation and shrinkage may occurduring roll forming process, thereby giving rise to a slight difference between the longitudinal length of the bulged projections 713 formed on the preliminary shaped plate 710a and the circumferential length of the preforrning groove 31 in the upper forming roll 3 of the first forming stand A. This may result in the necessity for a fine adjustment of the spacing between the two planes which include the axes of the forming rolls of the respective forming stands A and B. In this manner, such spacing may not be strictly an integral multiple of the circumferential length of the unit comprising the preforming grooves 31 and the flat surface 32 of the upper forming roll 3 of the first forming stand A. However, such slight differences in the spacing remain within design tolerances in the apparatus of this kind and do not affect the preformance of the invention.

It would appear that even without the provision of a synchronizing device to be described later, the second forming stand B could be able to form bulged projections 713b continuously in the exact form identical with the bulged projections 703 of the desired shaped plate 700 without producing any misalignment with the preformed bulged projections 713a from the first forming stand A, if the cylindrical roll diameters of the forming rolls in the first and second forming stands were the same and these rolls were driven for rotation at the same speed with initial adjustment so that the position in time at which the starting end s, of the

pre-forming grooves

31, 31 in the upper roll 3 interengage with the starting end s, of the

pre-forming projections

41, 41 on the lower forming roll of the first forming stand A in a plane which includes the axes of both of these forming rolls coincides with the position in time at which in the second forming stand B, the interengagement between the starting end s of the finish-forming

grooves

51, 51 in the upper forming roll 5 and the starting end 5 of the finish-forming

projections

61, 61 on the lower forming roll 6 occurs in a plane which includes the axes of both of these forming rolls.

However, this remains to be a theoretical possibility only. In practical roll forming operations, there may exist a slight difference between the circumferential length of pre-forming grooves 31 and projections 41 of the rolls in the first forming stand A and the circumferential length of finish-forming

grooves

51, 51 and

projections

61, 61 of the rolls in the second forming stand, or an elongation or shrinkage in the plate member 710 may occur lengthwise during forming operations, with consequence that after repeated forming cycles, there will be an increasing amount of misalignment between the position of pre-formed plate member-710 in the first forming stand A and the position thereon to which the finish-forming is applied by the second forming stand B, thereby preventing a shaped plate of exact form from being formed.

Therefore, in the apparatus according to the present embodiment of the invention, the pre-forming of the bulged projections by the first forming stand A is effected concurrently with the finish-forming of the bulged projections by the second forming stand B. In addition the diameter of the forming rolls in the second forming stand B is made smaller than the diameter of the forming rolls in the first-forming stand A, so that upon completion of approximately one revolution of the forming rolls in both the first and second forming stands to effect the pre-forming and finish-forming, respectively, the starting end s of the finish-forming grooves 51 and the starting end s of the projections 61 of the forming rolls in the second forming stand A always assume advanced angular positions with respect to the starting end s, of the pre-forming grooves 31 and the starting end S of the projections 41 of the forming rolls in the first forming stand A. Thereupon, a synchronizing device operates the electromagnetic clutch and brake 23, by abutment of the eccentric cam 27 against the normally closed limit switch 28, to interrupt momentarily the rotation of onlythe forming rolls in the second forming stand B, and operates the electromagnetic clutch and brake 23 to restart the rotation of the forming rolls in the second forming stand B upon detection, by abutment of the eccentric cam 25 on the first forming stand A against the normally open limit switch 26, of such an angular position of the forming roll in the first forming stand A that there applies the coincidence in time between the interengagement of the starting end s, of the pre-forming grooves 31 in the upper forming roll 3 and the starting end s of the preforming projections 41 on the lower forming roll 4 of the first forming stand A in a plane which includes the axes of both these rolls to thereby bite in the plate member 710, and the inter-engagement of the starting end s of the finish-forming grooves 51 in the upper forming roll 5 and the starting end s of the finish-forming projections 61 on the lower forming roll 6 of the second forming stand B in a plane which includes the axes of both these rolls to there by bite in the preformed or preliminary shaped plate 710a. Referring to FIG. 9 for a more specific description of the positions of the limit switches 26 and 28 relative to their operating eccentric cams and 27, the eccentric cam 27 on the second forming stand B is located at a position such that it abuts against the normally closed limit switch 28 to stop the upper and lower forming

rolls

5 and 6 of the second forming stand B only when the groove 521 formed in the flat surface 52 of the upper forming roll 5 and the groove 621 formed in the flat surface 62 of the lower forming roll 6 come opposite to each other.

On the other hand, the eccentric cam 25 on the end of the shaft for thelower forming roll 4 of the first forming stand A is located so that it abuts against the normally open limit switch 26 to restart the rotation of the upper and lower forming rolls 5 and 6 of the second forming stand B which have once stopped, at the time when the upper and lower forming rolls 3 and 4 of the first forming stand A reach such angular positions that the circumferential length s 0, measured along the cylindrical roll surface 30 of the upper forming roll 3 between the position of the starting end S, of the grooves 31 in the upper forming roll 3 of the first form ing stand A and the line of intersection c, of the cylindrical roll surface 30 of the upper forming roll 3 with the plane which includes the axes of the upper and lower forming rolls 3 and 4, such position being that which the starting end s, assumes when the rolls in the second forming stand B remains at rest, by virtue of the abutment of the eccentric cam 27 against the normally closed limit switch 28, with the groove 521 in the flat surface 52 of the upper forming roll 5 opposite to the groove 621 in the flat surface 62 of the lower forming roll 6, (or the circumferential length s c measured along the cylindrical roll surface 40 of the lower forming roll 4 of the first forming stand A between the corresponding position of the starting end s and the line of intersection c, of the cylindrical roll surface 40 of the lower forming roll 4 with the plane which includes the axes of the upper and lower forming rolls 3 and 4), becomes identical to the circumferential length s 0 measured along the cylindrical roll surface 50 between the position of the starting end s of the grooves 51 in the upper forming roll 5 of the second forming stand B which it assumes when the second forming stand stays at rest and the line of intersection c of the cylindrical roll surface 50 of the upper forming roll 5 with the plane which includes the axes of the upper and lower forming rolls 5 and 6 (or to the circumferential length s 6 measured along the cylindrical roll surface between the corresponding position of the starting end s of the projections 61 on the lower forming roll 6 and the line of intersection c of the cylindrical roll surface 60 with the plane which includes the axes of the upper and lower forming rolls 5 and 6). The

eccentric cams

25 and 27 are arranged so that before the eccentric cam 25 moves away from the normally open limit switch 26, the eccentric cam 27 on the second forming stand B moves away from the normally closed limit switch 28.

Referring to FIGS. 8 and 9, the operation of the synchronizing device will be described in connection with the apparatus of the present embodiment. For the convenience of description, it will be assumed that the second forming stand B has just completed the finishforming of one of the bulged projections 7l3b and that a flat portion 712b leading to the next bulged projection 713b now lies in the gap between the upper and lower forming

rolls

5 and 6, the latter rolls being at rest (because of the abutment of the eccentric cam 27 against the normally closed limit switch 28) with the groove 521 in the flat surface 52 of the upper forming roll 5 and the groove 621 in the flat surface 62 of the lower forming roll 6 being opposite to each other.

Regardless of the halted rotation of the forming rolls in the second forming stand B, the forming rolls in the first forming stand A continue to rotate, and when the latter rolls reach such angular positions that the circumferential length s, c, measured along the cylindrical surface 30 from the starting end s of the grooves 31 in the upper forming roll 3 of the first forming stand A to the line of intersection becomes equal to the circumferential length s 0 measured along the cylindrical roll surface 50 from the starting end s of the grooves 51 in the upper forming roll of the second forming stand B, which at this time remains stationary with the

grooves

521 and 621 being opposite, to the line of intersection c the eccentric cam 25 secured to the lower forming roll 4 of the first forming stand A is allowed to abut against the normally open limit switch 26 to close it, thereby enabling a current flow through the relay coil 80 in the circuit 7 of FIG. 8, whereby the normally closed contact 82 thereof associated with the brake coil 232 of the electromagnetic clutch and brake 23 is opened to deenergize the coil 232 and deactuate the brake, while the normally open contact 81 thereof associated with the clutch coil 231 is closed to energize the clutch coil 231 and actuate the clutch. Thereupon, the rotative drive from the motor 22 is transmitted to the forming rolls in the second forming stand B, which therefore start to rotate.

In this manner, the forming rolls in the second forming stand B rotate in synchronism with the rolls in the first forming stand A. Because of the coincidence, between the first and second forming stands, in the timing of interengagement between the upper and lower forming rolls therein or more specifically, the interengagement between the starting end s, of the grooves 31 in the upper forming roll 3 and the starting end s, of the projections 41 on the lower forming roll 4 which takes place in a plane that includes the axes of both these rolls to bite in the plate member 710 coincides in time with the interengagement between the starting end s of the grooves 51 in the upper forming roll 5 and the starting end s of the projections 61 on the lower forming roll 6 of the second forming stand B which takes place in a plane that includes the axes of both of these rolls to bite in the pre-formed or preliminary shaped plate 7l0a, so that the second forming stand B is operable to provide finish-forming of bulged projections 713a on the pre-formed plate 710a into bulged projections 713b which have the same configuration as the bulged projections of the desired shaped plate 700, without producing any misalignment. Thereafter the second forming stand B operates to feed the flat portion 712!) leading to the next bulged projections 713b by way of opposing

flat surfaces

52 and 62 on the upper and lower forming

rolls

5 and 6, respectively, which do not apply any deforming stress to the flat portion. When the upper and lower forming

rolls

5 and 6 have completed one full revolution since their start and the groove 521 in the flat surface 52 of the upper forming roll 5 and the groove 621 in the flat surface 62 in the lower forming roll 6 come opposite to each other, the eccentric cam 27 secured to the lower forming roll 6 of the second forming stand B abuts against the normally closed limit switch 28 to open it (by this time, the eccentric cam 25 on the first forming stand A has already moved away from the normally open limit switch 26). As a result, there is no current flow through the relay coil 80 in the circuit 7 of FIG. 8, and hence the normally open contact 81 of the relay 8 interrupts the circuit through the clutch coil 231 to deactuate the clutch, while the normally closed contact 82 of the relay completes the circuit through the brake coil 232 to actuate the brake, thereby causing the upper and lower forming

rolls

5 and 6 to halt with the groove 521 formed in the flat surface 52 of the roll 5 opposing the groove 621 in the flat surface 62 of the roll 6.

Referring to FIG. 9, it will be seen that during the continued rotation of the upper and lower forming rolls 3 and 4 of the first forming stand A which run independently from the halt of rotation of the forming

rolls

5 and 6 of the second forming stand 13, the flat portion 712b of the pre-formed plate 710a which is positioned in the gap between the groove 521 in the upper forming roll 5 and the groove 621 in the lower forming roll 6 of the second formong stand B continues to move freely through the gap having an increased gap length as compared with the thickness of the plate member 710, in the direction indicated by arrow C to feed the preformed plate 710a into the second forming stand B until such time as the latter initiates its rotating motion as controlled by the abutment of the eccentric cam 25 on the first forming stand A against the normally open limit switch 26.

In this manner, the second forming stand B repeats the start and stop of rotary motion, while continuously providing a finish-forming of a pre-formed plate 710a into a finish-formed plate 710a so that a plurality of bulged projections 713a crosswise spaced apart at a given interval and having a narrow width crosswise and a required finite length longitudinally and having a gently arcuate profile in cross-section can be finishformed into bulged projections713b having angular corners 71 1b as shown in section in FIG. 7.

The finish-formed plate 71% obtained with the apparatus of the invention can be cut to a suitable length longitudinally to yield a shaped plate 700 as shown in FIG. 1, after removing by cutting the belt-

like projections

715 and 715 formed along the lateral edges thereof.

It is essential in the apparatus of the invention that the spacing between the plane which includes the axes of the both forming rolls in the first forming stand A and the plane which includes the axes of the both forming rolls in the second forming stand B be adjusted to an integral multiple of the circumferential length of one unit comprising the grooves 31 and the flat surface 32 of the upper forming roll 3 of the first forming stand A. It is also essential to provide a synchronizing device which operates so that the upper and lower forming rolls 5 and 6 of the second forming stand B be stopped at such position that the groove 521 in the flat surface 52 of the upper forming roll 5 and the groove 621 in the flat surface 62 of the lower forming roll 6 come opposite to each other, and then re-started for rotation when the upper and lower forming rolls 3 and 4 of the first forming stand A reach such angular positions that the circumferential length s, c, measured along the cylindrical roll surface 30 from the starting end s of the grooves 31 in the upper forming roll 3 to the line of intersection c becomes equal to the circumferential length s c measured along the cylindrical roll surface 50 from the starting end s of the grooves 51 in the upper forming roll 5 of the second forming stand B to the line of intersection c This assures that the time at which the starting end s located on the bite-in side, of the preforming grooves 31 of the upper forming roll 3 and the starting end s located on the bite-in side, of the pre-forming projections 41 on the lower forming roll 4 of the first forming stand A interengage to bite in the plate member 710 in a plane which includes the axes of the both rolls to thereby initiate the pre-forming operation to form bulged projections 713a coincides with the time at which the starting end s located on the bite-in side, of the finish-forminggrooves 51 in the upper forming roll 5 and the starting end s located on the bite-in side, of the finish-forming projections 61 of the lower forming roll 6 of the second forming stand B interengage to initiate bite-in in the bulged projections 7130 of the pre-formed plate 7100 that is continuously fed into the second forming stand B by the forming rolls of the first forming stand A. As a consequence, a full coincidence is achieved between the position of the bulged projections 713a of the pre-formed plate 710a as they are fed into the second forming stand B to be worked upon and the forming operation performed by the interengaging grooves 51 and projections 61 of the upper and lower forming rolls 5 and 6 of the second forming stand B.

In the present embodiment, the forming roll is provided with one unit comprising a shaped surface including the projections and flat surface other than the shaped surface, or one unit comprising a shaped surface including the grooves and a flat surface other than the shaped surface. However, the forming roll may be provided with a plurality of such units on its periphery.

While the embodiment described above deals with a shaped plate having bulged projections only on one side thereof, a pair of upper and lower pre-forming rolls 3' and 4' as shown in FIG. 10 can be used in a first forming stand A in combination with a pair of finishforming rolls 5' and 6 shown in FIG. 11 that comprise a second forming stand B. These modified forming rolls can be used in the similar manner as mentioned above to form continuously a shaped plate 700' having bulged projections alternately projecting in opposite directions as shown in section in FIG. 11, without substantial local reduction of plate thickness.

The apparatus according to the above embodiment can further be modified by replacing the guide plates 104 and 104' positioned at the outlet side of the second forming stand B by a plurality of

guide rollers

105, 105 having a profile partially corresponding to the crosssectional configuration of the finish-formed plate 710b as shown in FIG. 12 and rotatably arranged above and below the plate 710k in a sandwich manner, thereby permitting the finish-formed plate 71% from the second forming stand B to be reformed.

In the apparatus of the embodiment, there is provided a spacing in excess of the thickness of a plate member 710 between the opposing

flat surfaces

52 and 62 of the forming rolls in the second forming stand B when these rolls stay at rest. Such spacing is provided in the above embodiment by means of the

grooves

521 and 621 formed centrally in the

flat surfaces

52 and 62, respectively, but may be provided in any other manner so long as the gap formed therebetween is in excess of the thickness of a plate member.

As will be understood from the foregoing, the apparatus according to the invention comprises a first forming stand including a pair of pre-forming rolls, each of the pre-forming rolls being formed on its periphery with at least one unit that comprises a shaped surface and a flat surface other than the shaped surface, the rolls being disposed so that their shaped surfaces and flat surfaces come opposite to each other, respectively, a second forming stand including a pair of finish-forming rolls, each of the finish-forming rolls being formed on its periphery with at least one unit that comprises a shaped surface and a flat surface other than the shaped surface, the finish-forming rolls being disposed so that their shaped surfaces and flat surfaces come opposite to each other, respectively, the first and second forming stands being arranged such that a plane which includes the axes of the forming rolls of the first forming stand is parallel to a plane which includes the axes of the forming rolls of the second forming stand and the spacing between said planes is an integral multiple of the circumferential length of the unit comprising the shaped surface and flat surface of the forming roll in the first forming stand, a first drive means for continuously rotating the forming rolls of the first form ing stand at same but opposite peripheral speeds, a second drive means for rotating the forming rolls of the second forming stand at the same peripheral speed as that of the forming rolls of the first forming stand and in opposite directions, a synchronizing means for driving the second drive means in synchronism with the first drive means so as to cause the forming position by the forming rolls of the second forming stand to coincide with the forming position by the forming rolls of the first forming stand, and means in the second forming means for creating a spacing in excess of the thickness of a plate member between opposing flat surfaces of the forming rolls of the second forming stand when the second drive means is interrupted and the forming rolls in the second forming stand are halted. Initially, the shaped surfaces of the pre-forming rolls of the first forming stand coact to pre-form a plate member into plurality of bulged projections spaced apart at a given interval crosswise and each having a narrow width crosswise and a required finite length longitudinally, the bulged projections being formed in a configuration substantially close to that of the bulged projections on a desired shaped plate. Subsequently, the pre-formed bulged projections are finish-formed into a form which is equal to the form of bulged projections on the desired shaped plate, by the second forming stand that is operated for rotation by the synchronizing device so as to achieve a full coincidence between the preformed bulged projections and the shaped surfaces of the finish-forming rolls. Consequently, the forming operation is effected smoothly with little strain, bending and local thickness reduction, thus enabling shaped plates of exact size, form and appearance to be formed continuously.

I-Iaving described the invention, what is claimed is:

1. Roll forming apparatus comprising a first forming stand including a pair of pre-forming rolls, each of the rolls being formed on its periphery with at least one unit which comprises a shaped surface and a fiat surface other than the shaped surface, the rolls being disposed so that their shaped and flat surfaces come opposite to each other, respectively, a second forming stand including a pair of finish-forming rolls, each of the finish-forming rolls being formed on its periphery with at least one unit which comprises a shaped surface and a flat surface other than the shaped surface, the finish-forming rolls being disposed so that their shaped surfaces and flat surfaces come opposite to each other, respectively, the first and second forming stands being arranged such that a plane which includes the axes of the forming rolls of the first forming stand is parallel to a plane which includes the axes of the forming rolls of the second forming stand and the spacing between said planes is an integral multiple of the circumferential length of the unit comprising the shaped surface and flat surface of the forming roll in the first forming stand, a first drive means for continuously rotating the forming rolls of the first forming stand at same but opposite peripheral speeds, a second drive means for rotating the forming rolls of the second forming stand at the same peripheral speed as that of the forming rolls of the first forming stand and in opposite directions, a synchronizing means for driving the second drive means in synchronism with the first drive means so as to cause the forming position by the forming rolls of the second forming stand to coincide with the forming position by the forming rolls of the first forming stand, and means for creating a spacing in excess of the thickness of a plate member between the opposing flat surfaces of the forming rolls of the second forming stand when the second drive means is interrupted and the forming rolls in the second forming stand are halted, whereby the plate member is continuously formed into a shaped plate having a plurality of bulged projections spaced apart at a given interval crosswise and each having a narrow width crosswise and a required finite length longitudinally.

UNITED STATES PATENT OFFICE Q'ETlFICATE OF CQRECTIGN Patent No. ,917 Dated August 29 1972 Inventor(5) RYOTARQ HIKIDA, \ET. AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [73] "Toyoto chuo" should read Toyota Chuo Column 2, line 61, "axial" should read vertical Column 3, line 40, "3"- should read 2 line 55, "and", second occurrance, should read end eline 63, "and" should read or Column 4, line 28, "s should read line 30, "42" should read 41 Column 5, line 2, "760" should read 710a line 63,

"52" should read Ell Column 6, line 1, "52,52" should read 51,51 lines 8 and 9, 'Ycentrally" should read axially Column 7, line 14, "43" should read 62 line 46, "E: shouldread -r E1 -;,line. 49;, ,"F? should read F,F' Column 9, line 3?, "710' should read 710 b -a Co'iizu'mn 10, line 25, "713" should read 713a Column 12, line 55, "7131 should read 713a Column 13, line 2, "s should read s line 31, should read Signed and sealed this 20th day of November 1973.

(SEAL? Attest:

EDWARD M.FLETCHER,JR. RENE b. TEGTMEYER Attesting Officer Acting Commissioner vof Patent FORM (1069) USCOMM-DC suave-Pas W 15 GOVERNMENT PRINTING OFFICE: [959 O'-356-334. I

Claims

1. Roll forming apparatus comprising a first forming stand including a pair of pre-forming rolls, each of the rolls being formed on its periphery with at least one unit which comprises a shaped surface and a flat surface other than the shaped surface, the rolls being disposed so that their shaped and flat surfaces come opposite to each other, respectively, a second forming stand including a pair of finish-forming rolls, each of the finishforming rolls being formed on its periphery with at least one unit which comprises a shaped surface and a flat surface other than the shaped surface, the finish-forming rolls being disposed so that their shaped surfaces and flat surfaces come opposite to each other, respectively, the first and second forming stands being arranged such that a plane which includes the axes of the forming rolls of the first forming stand is parallel to a plane which includes the axes of the forming rolls of the second forming stand and the spacing between said planes is an integral multiple of the circumferential length of the unit comprising the shaped surface and flat surface of the forming roll in the first forming stand, a first drive means for continuously rotating the forming rolls of the first forming stand at same but opposite peripheral speeds, a second drive means for rotating the forming rolls of the second forming stand at the same peripheral speed as that of the forming rolls of the first forming stand and in opposite directions, a synchronizing means for driving the second drive means in synchronism with the first drive means so as to cause the forming position by the forming rolls of the second forming stand to coincide with the forming position by the forming rolls of the first forming stand, and means for creating a spacing in excess of the thickness of a plate member between the opposing flat surfaces of the forming rolls of the second forming stand when the second drive means is interrupted and the forming rolls in the second forming stand are halted, whereby the plate member is continuously formed into a shaped plate having a plurality of bulged projections spaced apart at a given interval crosswise and each having a narrow width crosswise and a required finite length longitudinally.