GB2098530A - Riveting machine for brake linings - Google Patents

Abstract

In a machine for riveting brake linings onto brake shoes, rivets are fed consecutively to a top dolly (10), which after the introduction of a rivet into a workpiece, performs the rivet deformation conjointly with a stationary bottom dolly (11). In the bottom dolly a spring-loaded centering pin (25) for workpiece alignment projects beyond the dolly head in the initial position. The top dolly (10) projects into a bore (12) of a housing (13) forming a rivet die plate which slides relative to the top dolly (10) and contains a rivet inlet (15) open to the side and connected to a rivet slide rail (8). A slider with a bevelled end face projects into the bore for initial engagement by a rivet, the slider being pushed aside before the rivet contacts the centering pin. <IMAGE>

Description

SPECIFICATION Rivetting machine for brake linings The invention relates to a rivetting machine, particularly for rivetting brake linings onto the brake lining carriers of brake shoes, with a rivet insertion device by which the rivets are fed consecutively by means of a rivet slide rail to a top dolly which, after the introduction of the rivet into the coincident bores of the workpieces formed by brake lining and brake lining carrier and compressed by means of a rivet die plate, performs the rivet deformation conjointly with a bottom dolly in which a centering pin serving for the preparation of the rivettings by workpiece alignment and which projects beyond the dolly head in the initial position, is axially mobile, is subject to the action of a spring and has such a length that the projecting front end completely penetrates the workpieces, and that the top dolly can be lowered together with the rivet transferred into a centre readiness position towards the bottom dolly, entraining the centering pin, as soon as the rivet strikes the latter.

In a known rivetting machine of this type (Prospectus of S. Dunkes GmbH, Kirchheim/Teck) the rivets, which are constructed as solid rivets, are respectively gripped by a gripper which is associated with the top dolly and which opens to release the rivet as soon as the top dolly stresses the rivet. The rivet entrains the workpieces counter to the spring action of the rivet die plate and is then, after the bottom limit position is reached, provided with the rivet head by the wobble rivetting process by the rotating bottom dolly with centering pin, which is constructed as a rivetting die.

This machine is extremely complicated due to the fact that a precisely operating control means must be associated with the gripper and a highly complicated drive system must be provided for the wobble movement during the solid rivet deformation.

It is the underlying aim of the invention to further develop the rivetting machine of the type initially stated, whilst eliminating the disadvantages mentioned, so that together with a considerable structural simplification the processing of hollow rivets is made possible and nevertheless at the same time a highly accurate rivet arrangement in the workpiece can be achieved which ensures the production of rivetted joints of highly durable quality, which are therefore reliable particularly during braking.

The rivetting machine according to the invention, in which this aim has been achieved, is substantially characterised in that the bottom dolly is mounted stationary in the machine frame and that the centering pin exhibits in the lowered work position a projection projecting beyond the dolly head, which is provided with a contraction formed by a reduction of its diameter and determines the internal contour of the hollow rivet head to be formed, and that the top dolly projects by its front end into a bore of a rivet housing forming the rivet die plate, which is arranged slidably counter to spring action along the top dolly guiding it in the region between two stationary stops, exhibits a rivet inlet open to the side and connected to the rivet slide rail and comprises at least one slide extending transversely to the bore axis, which projects partly into the rivet transport path by an end face bevelled and aligned so that the rivet is released only after the lowering of the top dolly, the rivet housing being entrained, until it strikes the bottom stop and a compression spring associated with the slide is tensioned.

In this manner a highly accurate alignment of the individual rivets with reference to the workpiece bores receiving them is ensured, which is highly essential particularly when the workpieces are brake linings and brake lining carriers of brake shoes, the joints between which are subject to high specifications as to quality because of the great stresses which they are required to withstand. The accurate alignment during the introduction of the rivets into the workpiece bores ensures an accurate rivet deformation and the formation of perfect rivet heads during the subsequent stressing of the rivet by the dolly. Simultaneously the development of a rivetting machine according to the invention produces a structurally simple design. No onerous wobble rivetting drive is necessary, as in the previously known rivetting machine referred to initially.

It has been found highly advantageous, particularly from a structural standpoint, if the top dolly is anchored to the underside of a dolly retaining plate controllable preferably hydraulically towards the bottom dolly, and there is provided between the rivet housing and the dolly retaining plate at least one pre-tensioned traction spring and a comparatively harder constituted compression spring, which is dimensioned shorter than the distance between the dolly retaining plate and the rivet housing.This construction ensures that the rivet housing is maintained in abutment against the top stop by the traction spring until the compression spring, which is exposed when the dolly arrangement occupies the initial position, moves into abutment with the top dolly plate during the lowering of the top dolly retaining plate with top dolly with partial relaxation of the traction spring, then after partial compression lifts the rivet housing from the top stop and entrains it until it finally strikes the bottom stop. The rivet previously transferred into the readiness position then passes the compression-spring-loaded slide with further compression of the compression spring and relaxation of the traction spring and is finally deformed by the two dollies in an exact position between the latter.

It has been found highly convenient from the structural standpoint if the top and/or bottom stop for the rivet housing is formed respectively by two strips connected to the machine frame and arranged on each side of the top dolly and mutually parallel transversely to the axis of the latter, and if the rivet housing exhibits projecting edges extending mutually parallel, in the movement path of which the strips are located.

As a further convenient development of the rivetting machine, a feature has been found highly advantageous, whereby the machine frame comprises two columns and a crossmember which is braced by the latter and carries particularly the rivet insertion device and the drive device for the dolly retaining plate movable between the columns, and whereby the one ends of the strips are connected to the one column and the other ends of the strips to the other column.

In order to ensure a uniform retaining effect upon each rivet when it is stressed by the top dolly, it has been found highly favourable for two slides with bevelled end face loaded towards each other by a compression spring transversely to the axis of the bore of the top dolly to be associated with the rivet inlet of the rivet housing, because then the restraining force acts upon the rivet from both sides and hence in balance.

It has been found highly favourable, preferably when rivetting brake linings onto brake shoes, if, for the simultaneous placing of two rivets per work stroke, the dolly retaining plate is provided with two top dollies and the rivet housing with two bores which each comprise a rivet inlet with slide arrangement. By means of a rivetting machine developed in this way, each of the pairs of rivets located on each side of the brake lining bar, which are customarily mutually aligned, can be placed accurately in one work stroke of the machine in each case.

In a rivetting machine in which the centering pin exhibits, within the bottom dolly, a shoulder formed by enlargement of diameter, by which it passes by the action of the spring into abutment with a corresponding step of a centering pin chamber of the bottom dolly, it is highly advantageous from the standpoint of an accurate rivet deformation obtainable by particularly simple means, if a stop in the form of a cylindrical element, limiting the sliding stroke of the centering pin, is provided in the centering pin chamber, and that a guide pin projecting into a central bore of the centering pin is associated with the cylindrical element, and penetrates the turns of the spring formed by a helicoidal spring.It is in fact easy to dimension the height of the cylindrical element and thus to predetermine the position of the centering pin during the rivet deformation in a particularly simple manner.

The cylindrical element is conveniently provided with a central bore which serves to house the helicoidal spring, and the guide pin extends through the central bore of the cylindrical element. Due to this construction it is possible to use a relatively long spring without prejudice to the stop function of the cylindrical element, and without having to increase the overall height.

It has been found highly advantageous from the standpoint of practical use of the machine if two bottom dollies with centering pin are provided at a mutual interval on a common base plate, and if in each case a support, which rests upon the base plate by at least one spring, is arranged outside the bottom dollies to brace the brake shoe during the rivetting operation. By means of this support the brake shoes can be aligned with the dollies relatively rapidly and conveniently, because the support already absorbs the weight of the brake shoes during the alignment. Only during the subsequent rivetting operation are the brake shoes lowered together with the support onto the bottom dolly by the action of the top dolly with compression of the spring.It has been found particularly favourable in this respect if an abutment projecting beyond the surface of the support and serving for the alignment of the brake shoes is associated with each support on its outside.

Further particulars, advantages and features of the invention will emerge from the following description and from the drawing, to which attention is expressly directed for the disclosure of all particulars not described in the text. In the drawing: Fig. 1 shows an elevation of the rivetting machine according to the invention, partly in section, Fig. 2 shows a side elevation of the rivetting machine according to Fig. 1, partly in section, Fig. 3 shows, on a larger scale, an elevation of the top dolly with the dolly retaining plate carrying it and with the rivet housing carried by it, partly in section along the line Ill-Ill in Fig. 5, Fig. 4 shows a side elevation of the particulars illustrated in Fig. 3, partly in section along the line IV--IV in Fig. 5, Fig. 4a shows a plan of the slide illustrated in Fig. 4 etc., Fig. 5 shows a plan of the dolly plate according to Fig. 3, Fig. 6 shows an elevation of the bottom dolly, and of the base plate carrying it with supports and abutments for the brake shoes, partly in section along the line VI--VI in Fig. 7, and Fig. 7 shows a plan of the particulars illustrated in Fig. 6, but after removal of the bottom dolly, supports and abutments.

As shown in Figs. 1 and 2, the rivetting machine illustrated comprises a machine frame with two vertical columns 2 starting from a machine base 1 and with a crossmember 3 supported by them. This crossmember 3 carries a hydraulically operated drive apparatus 4, not shown in detail, for a dolly retaining plate 5 movable vertically between the columns 2. Two rivet insertion devices 6, each of which comprises a rivet storage hopper 7, known per se, with singler and a rivet slide rail 8, are also arranged on the crossmember 3. A rivet stop 9, controlled by the vertical movement, by means of which the rivets are passed on individually as a function of the work stroke, is associated with each rivet slide rail 8. The rivets pass via the lower part of the rivet slide rail into the region of action of a top dolly 10, which is anchored to the underside of the dolly retaining plate 5.A bottom dolly 11 mounted stationary in the machine frame is associated with each of the top dollies 10.

The top dolly 10 projects by its front end into a bore 12 of a rivet housing 13 serving as part of a so-called rivet die plate. This rivet housing is slidable along the top dolly 10 counter to the action of a compression spring 1 4 which is arranged between the dolly retaining plate 5 and the rivet housing 13.

Figs. 3 and 4 show in detail the arrangement and the interaction of the top dollies 10 with the rivet housing 13 carried by them. It is clear that the rivet housing 1 3 comprises at each of its narrow sides a rivet inlet 1 5. The latter is connected to the lower end of the associated rivet slide rail 8.On the underside of the rivet housing there are present, for each bore 12, two sliders 1 7 stressed towards each other transversely to the axis of the bore of the top dolly 10 by a compression spring 16, and having an end face 18 projecting partly into the rivet transport path and shaped, bevelled and aligned so that each rivet is released by the rivet housing 1 3 only following a relative movement of the top dolly 10 with reference to the rivet housing 1 3 with tensioning of the compression springs 1 6 associated with the sliders 1 7. The relative mobility of the top dolly 10 with reference to the rivet housing 13 is ensured by stationary top and bottom stops 19 and 20 located in the movement path of the rivet housing 13.The top stop 19 and the bottom stop 20 for the rivet housing 1 3 are each formed by two strips arranged on each side of the top dolly 10 and mutually parallel transversely to the axis of the latter, which are connected to the machine frame.

As Fig. 4 shows, the rivet housing 13 exhibits projecting edges 21 extending mutually parallel, in the movement path of which the strips forming the stops 1 9, 20 are located. It is clear from Fig. 1 that the said strips are connected by their one ends to the one column 2, and the other ends of the strips to the other column 2. Pretensioned traction springs 22, in comparison to which the compression springs 1 6 are designed harder, and by the action of which the rivet housing 13 abuts by its edges 21 against the strips forming the top stops 19, are provided between the rivet housing 13 and the dolly retaining plate 5.

The bottom dollies 11 associated with the top dollies 10 are arranged on a base plate 23. In order to ensure stable anchorage of the bottom dollies 11 with reference to the base plate 23, they are each arranged in a bore of a bottom housing 24 fixed on the base plate 23. A centering pin 25 serving to prepare the rivetting operations by workpiece alignment, and projecting beyond the dolly head in the initial position, is arranged in each bottom dolly 11. Each centering pin 25 is axially mobile and subject to the action of a spring 26. The length of each centering pin 25 is dimensioned so that the projecting front end fully penetrates the workpieces, and that the top dolly 10 together with the rivet transferred into a centred readiness position can be lowered towards the bottom dolly 11, the centering pin 25 being entrained, as soon as the rivet strikes the latter.In the lowered work position the centering pin 25 exhibits a projection 27 which projects beyond the dolly head and is provided with a contraction 28 formed by a reduction of the diameter. This determines the internal contour of the hollow rivet head to be formed during the rivetting operation. The centering pin 25 exhibits, within the bottom dolly 11, a shoulder 29 formed by an enlargement of diameter, by which it comes into abutment with a corresponding step 30 of a centering pin chamber 31 under the action of the spring 26. A stop, in the form of a cylindrical element 32, limiting the sliding stroke of the centering pin 25 is present in the centering pin chamber 31. This cylindrical element is provided with a central bore 33, through which a guide pin 34 extends into a central bore 35 of the centering pin 25.This guide pin 34 penetrates the turns of the spring 26, formed by a helicoidal spring, the outside diameter of which is somewhat smaller than the inside diameter of the central bore 33 of the cylindrical element 32.

A support 36 to brace the brake shoes during the rivetting operation is provided outside each of the bottom dollies 11. Each support 36 exhibits on its underside two blind bores 37 arranged at a mutual interval, each to accommodate a projecting rubber spring 38. The bottom housing 24 is screwed by its end face in each case to a cover plate 39 which covers a recess 40 of the bottom housing 24, in which the support 36 is guided with vertical sliding mobility. The interval of the support 36 from the base plate 23, and hence the pretension of the rubber springs 38, is adjustable. In order to adjust the pretension of the rubber springs 38, the support 36 is provided with a lateral projection 41 in the form of a screw head, which projects into an aperture 42 and influences the adjustable stop 43 formed by a screw.

Each support 36 is provided externally with an abutment 44 projecting beyond its surface and serving for the brake shoe alignment. For this purpose the interval of the mutually confronting edges 45 of the abutments 44 is coordinated precisely with the width of the workpieces to be rivetted together, in the present case of the brake lining carrier of the brake shoe. Each abutment 44 is constructionally integral with a bar 46, by which it is firmly connected in each case to the bottom housing 24. In the example illustrated the bar 46 is connected to the cover plate 39 by screws 47, to receive which screwthreaded bores 48 are provided in the cover plate 39. In order to ensure a precise alignment of the bottom housing 24 with reference to the base plate 23 connected to it by screw bolts 49, mutually aligned bores 50 are provided to receive keys, not shown in detail.

Figs. 3 to 5 show further details of the structural constitution of the top rivet housing 1 3 in conjunction with the sliders 1 7. As is clear, particularly from Fig. 4 in conjunction with Fig. 4a, the sliders 17 each exhibit a blind bore 51, into which the one end of the respectively associated compression spring 16 protrudes. The other end of the spring is braced in each case against a cover plate 52 at the outer end of a slide housing 53. By the action of the compression springs 1 6, the sliders 17 each abut by a lateral projection 54 against an edge of the rivet housing 1 3.

Simultaneously, as Fig. 4a shows, the slides enclose a rivet passage 55 open towards the inlet 1 5. The oblique end faces 18 of the slides 1 7 are each of quadrant-shaped construction on their one side.

Fig. 3 shows that the dolly retaining plate 5 is connected to a cylinder pin 56 which projects into the turns of the compression spring 1 4 constructed as a helicoidal spring and secures the latter against lateral deviation during its deformation. The compression spring 14 is arranged with its free end in a central bore projection 57 of the rivet housing 13. Fig. 5 shows clearly that the cylinder pin 56, and hence the compression spring 14, are arranged in the centre of the rivet housing 13. The bores 12 associated with the two top dollies 10 in the rivet housing 13 lie in a common longitudinal plane with the compression spring 14. The traction springs 22, on the other hand, lie in a plane oriented transversely to the common plane of the bores 12 for the top dollies 13 and extending through the axis of the compression spring 14. They each engage by their one end bolts 58, which are passed through bores in the dolly retaining plate 5 and rest by their head 59 upon a bore enlargement. In similar manner the other end of each of the traction springs 22 is connected to a bolt 60 which is braced by its head 61 against a bore shoulder of the rivet housing 13.

Claims (16)

1. Rivetting machine for rivetting two workpieces with coincident bores, particularly brake linings onto brake lining carriers of brake shoes, comprising: a machine frame with a bottom dolly mounted stationary thereon and with a top dolly reciprocable relative to the bottom dolly, which top dolly enters the top of a bore in a rivet housing forming a rivet die plate, which housing is slidable relative to the top dolly between a top stop and a bottom stop to which top stop it is biased by a spring; the rivet housing having a lateral rivet inlet to the bore connected to a rivet supply means for feeding rivets consecutively into the bore, and at the lower end of the bore slidable transversely to the axis of the bore, a slider having a bevelled end-face adapted to be engaged by a rivet, the slider being biased by a spring to project partly into the path of a rivet out of the bore and being slidable out of this path by the rivet engaging the bevelled end face exerting pressure on it; the bottom dolly having therein an axially mobile centering pin serving for the preparation of rivetting by workpiece alignment, which pin projects in its uppermost position beyond the head of the lower dolly and is spring biased to this position, and whose length is such that in its uppermost position its projecting front end completely penetrates the workpieces to be rivetted, and which pin has a lowermost position in which only its tip of reduced diameter projects beyond the head of the bottom dolly; the operation of the machine being such that on the top dolly being lowered towards the bottom dolly for a rivetting operation it first contacts the top of a rivet fed into the bore, the bottom of this rivet engages the slider and is initially held thereby in the rivet housing which is entrained thus to move with the top dolly and the rivet until the housing hits its bottom stop when the rivet pushes aside the slider and contacts the centering pin which is depressed to its lowermost position with the rivet inserted in the workpieces and the top and bottom dolly finally co-operate to deform the rivet to secure the workpieces together, with the top of the centering pin of reduced diameter determining the internal contour of the hollow rivet head to be formed.

2. Rivetting machine according to claim 1, characterised in that the top dolly is anchored to the underside of a dolly retaining plate controllable preferably hydraulically towards the bottom dolly, and by the provision between the dolly retaining plate of at least one predetermined traction spring and a comparatively harder constituted compression spring, which is dimensioned shorter than the distance between the dolly retaining plate and the rivet housing.

3. Rivetting machine according to claim 1 or 2, characterised in that the top and bottom stops for the rivet housing are formed respectively by two strips connected to the machine frame and arranged on each side of the top dolly and mutually parallel transversely to the axis of the latter, and that the rivet housing exhibits projecting edges extending mutually parallel, in the movement path of which the strips are located.

4. Rivetting machine according to claim 3, characterised in that the machine frame comprises two columns and a crossmember which is braced by the latter and carries particularly the rivet insertion device and the drive device for the dolly retaining plate movable between the columns, and that the one ends of the strips are connected to the one column and the other ends of the strips to the other column.

5. Rivetting machine according to any of claims 1 to 4, characterised in that two sliders with bevelled end faces loaded towards each other by a compression spring transversely to the axis of the bore of the top dolly are associated with the rivet inlet of the rivet housing.

6. Rivetting machine according to any of claims 1 to 5, characterised in that, for the simultaneous placing of two rivets per work stroke, the dolly retaining plate is provided with two top dollies, and the rivet housing with two bores, which each comprise a rivet inlet with slider arrangement.

7. Rivetting machine according to claim 6, characterised in that the compression spring is arranged in the centre of the rivet housing, but a bore belonging to one of the two ends in the rivet housing is associated with each of the two top dollies, and that the compression spring is located in the plane common to the two bores.

8. Rivetting machine according to claim 7, characterised in that a cylinder pin projecting into the helicoidal spring turns is anchored to the dolly retaining plate in order to guide the compression spring, which is constructed as a helicoidal spring, during its deformation.

9. Rivetting machine according to any of claims 4 to 8, characterised in that two traction springs are provided between the dolly retaining plate and the rivet housing and that these traction springs are located in a plane extending transversely to the common plane of the bores for the top dollies and passing through the axis of the compression spring.

10. Rivetting machine according to any of the foregoing claims 1 to 9, wherein the centering pin exhibits within the bottom dolly a shoulder formed by enlargement of diameter, by which it comes into contact subject to the action of the spring with a corresponding step of a centering pin chamber of the bottom dolly, characterised in that a stop in the form of a cylindrical element limiting the sliding stroke of the centering pin is provided in the centering pin chamber, and that a guide pin projecting into a central bore of the centering pin is associated with the cylindrical element, and penetrates the turns of the spring formed by a helicoidal spring.

11. Rivetting machine according to claim 10, characterised in that the cylindrical element is provided with a central bore which serves to house the helicoidal spring, and that the guide pin extends through the central bore of the cylindrical element.

1 2. Rivetting machine according to either of claims 10 and 11, characterised in that two bottom dollies with centering pin are provided at a mutual interval on a common base plate, and that in each case a support, which rests upon the base plate by at least one spring, is arranged outside the bottom dolly to brace the brake shoe during the rivetting operation.

13. Rivetting machine according to claim 12, characterised in that the spring is formed by a rubber spring.

14. Rivetting machine according to claim 12 or 13, characterised in that the distance of the support from the base plate, and hence the pretension of the spring, is adjustable.

1 5. Rivetting machine according to claim 14, characterised in that the support exhibits a lateral projection, with which an adjustable stop formed by a screw is associated.

16. Rivetting machine according to any of claims 12 to 1 5, characterised by the association with each support of an abutment projecting on its outside beyond the surface of the support and serving to align the brake shoe.

1 7. Rivetting machine according to claim 16, characterised in that each abutment is constructionally integral with a bar, by which it is connected firmly to the bottom housing in each case.

1 8. Rivetting machine substantially as hereinbefore described with reference to the accompanying drawings.