GB2537516A

GB2537516A - Pressing device

Info

Publication number: GB2537516A
Application number: GB1608252.1A
Authority: GB
Inventors: Hildebrandt Oliver
Original assignee: Supfina Grieshaber GmbH and Co KG
Current assignee: Supfina Grieshaber GmbH and Co KG
Priority date: 2014-01-13
Filing date: 2015-01-09
Publication date: 2016-10-19
Anticipated expiration: 2035-01-09
Also published as: CN105792987A; WO2015104372A1; DE202014000094U1; KR102341025B1; GB2537516B; KR20160110939A; GB201608252D0; CN105792987B

Abstract

The invention relates to a pressing device (10) comprising a pressing tape (48) for pressing finishing tape against circumferential surfaces (38) of substantially cylindrical workpiece sections (36) during a finishing process in such a way that the finishing tape is pressed against a circumferential surface (38) with a specific pressing force at a pressure angle (46), the pressing tape (48) being supported on two supporting bearings (52) which are arranged on both sides of the pressure angle (46) and which are part of a supporting element (26) that has at least one pivot axis (28).

Description

P/25528.GBW

Description

Pressing device [0001] The invention relates to a pressing device having a pressing tape for pressing finishing tape into contact with circumferential surfaces of substantially cylindrical portions of workpieces in a finish-machining operation in such a way such that the finishing tape is pressed into contact with a circumferential surface with a force for pressing into contact over an engaged angle.

[0002] Known from EP 2 212 058 B1 is a pressing device in which a pressing tape is fastened to two bearing surfaces, arranged at a distance from one another, on a carrying member, the front face of the pressing tape being provided with an anti-slip securing means which makes it difficult for the finishing tape to slip relative to the pressing tape within the engaged angle.

[0003] Taking the above as a point of departure, the object underlying the present invention is to provide a pressing device which makes a high accuracy of machining possible.

[0004] This object is achieved in accordance with the invention in a pressing device of the kind specified in the opening paragraph by supporting the pressing tape into contact on two supporting bearing surfaces which are arranged on either side of the engaged angle and which belong to at least one supporting member having at least one axis of pivot.

[0005] The support according to the invention of the pressing tape creates at least one additional degree of freedom for orienting the pressing tape and a finishing tape relative to a workpiece to be machined. Degrees of freedom of this kind are responsible for evening out the forces for pressing into contact, particularly in respect of finish machining of workpieces of differing diameters. In particular, the pressing forces acting on the two supporting bearing surfaces can be evened out. The pressing device according to the invention thus enables pressing forces to be evened up and excessively high pressing forces to be avoided. This ensures that high stock-removal rates do not detract from the accuracy of machining.

[0006] The pressing tape is preferably merely supported on the supporting bearing surfaces and is not fastened in place at these points. A particular P/25528.GBW preference in this connection is for the pressing tape to have on both sides of the supporting bearing surfaces, looking in the direction defined by the tape, free portions which are not supported. A central portion of tape is provided between the supporting bearing surfaces in this case. This is the portion of tape which presses the finishing tape into contact with a circumferential surface of a workpiece to be finish-machined over the engaged angle. Those free portions of tape which are arranged at outward points relative to the free central portion of tape enable the pressing tape to be able to be fastened in place somewhere remote from the supporting bearing surfaces and in particular to components provided separately from the supporting member.

[0007] In one embodiment of the invention, the supporting bearing surfaces are substantially inelastic and are for example made of a metallic material.

[0008] In a preferred embodiment, the supporting bearing surfaces are made of an elastically yielding material and in particular from an elastomer. A supporting bearing surface of this kind may for example be formed by a cushion able to be compressed in the direction of pressing into contact and/or by a roller movable about an axis of pivot or rotation.

[0009] An elastomeric material particularly well suited to the supporting bearing surfaces is "Vulkollan" (a trademark registered in the name of Bayer AG or associated companies). What this name designates as a material is a polyurethane elastomer made by Bayer MaterialScience AG, 51368 Leverkusen, Germany. This material is supplied in a harder, so-called "solid" form and in a softer so-called "cellular" form. If solid Vulkollan is used, higher forces for pressing into contact can be generated and what results is a steadier supporting action suitable for particularly high rates of stock removal. If cellular Vulkollan is used, the result is softer support which is suitable for particularly high accuracies of machining.

[0010] Further degrees of freedom for the mounting of the pressing tape can be created if the pressing tape is fastened to a holder provided separately from the supporting member.

[0011] If a holder of this kind is used, it is preferable for the supporting member to be pivotable relative to the holder about the at least one axis of pivot.

P/25528.GBW [0012] The holder may for example have a receiving space for the supporting member to be arranged in, which receiving space has a U-shaped boundary. It is possible in this case for surfaces forming parts of the U-shaped boundary of the receiving space to act at the same time as a guide for the supporting member which is movable relative to the holder.

[0013] A particular preference is for the holder to be connected to an arm for pressing into contact or to be part of the arm for pressing into contact and for the arm for pressing into contact to be pivotable about an axis of the arm for pressing into contact. In this way, it is possible for use to be made of an arm for pressing into contact, as known per se, of a pressing device.

[0014] The at least one axis of pivot of the supporting member is for example an axis of tilt which extends relative to a workpiece to be machined in a direction parallel to the axis of rotation of the workpiece. An axis of tilt of this kind enables a particularly good equalisation of forces for pressing into contact to be achieved when machining workpieces of differing diameters.

[0015] In addition to or alternatively to an axis of tilt, it is possible for an axis of swing which extends relative to a workpiece to be machined in a direction perpendicular to the axis of rotation of the workpiece to be provided at least as one axis of pivot. This enables forces for pressing into contact also to be evened up over a width of circumferential surface to be finish-machined on the workpiece which is measured parallel to the axis of rotation of the workpiece.

[0016] Described below are forms of supporting bearing surface and forms of front face and/or rear face for the pressing tape and these, and in particular the measures which are described below for acting on the friction between the finishing tape and the pressing tape and/or between the pressing tape and the supporting bearing surfaces are advantageous even in their own right and can even be used in pressing devices whose supporting members do not have an axis of pivot (i.e. pressing devices as claimed in claim 1 but with the exception of the feature that the supporting member has an axis of pivot).

[0017] In a further embodiment of the invention, provision is made for the pressing tape to have frictional areas at the points where the supporting P/25528.GBW bearing surfaces are situated, for the pressing tape to have an area for pressing into contact between the supporting bearing surfaces in the region of the engaged angle, and for the static friction between the frictional areas of the pressing tape and a rear face of the finishing tape to be higher than the static friction between the area for pressing into contact of the pressing tape and the rear face of the finishing tape. In this way, the friction between the pressing tape and the rear face of the finishing tape can be increased in a region outside the engaged angle. At the same time, the rear face of the finishing tape co-operates with the smooth area for pressing into contact of the pressing tape in the region of the engaged angle, which means that the forces from the finishing tape which act on the circumferential surface of the workpiece are evened up and make possible highly accurate finish-machining of the circumferential surface of the workpiece. In particular, it is possible to prevent any adverse effect which a roughened (irregularly roughened locally) area for pressing into contact could potentially have on the accuracy of the finish-machining. It is preferable for the mean roughness depth Rz of the area for pressing into contact to be a maximum of 3 micrometres and in particular a maximum of 1 micrometre.

[0018] To set the static friction in the region of the frictional areas and in the region of the area for pressing into contact, there are known measures which are available to the person skilled in the art. One such measure makes provision for the roughness of the frictional areas to be higher than that of the area for pressing into contact. For example, a metal pressing tape may be used which is roughened only in the region of the supporting bearing surfaces and/or which is provided with an additional coating, in particular of a cutting material (e.g. diamond).

[0019] In addition to or alternatively to this, it is possible for the supporting bearing surfaces to have roughened surfaces or friction coatings which cooperate with a rear face of the pressing tape which is remote from the finishing tape and/or for the rear face of the tape for pressing into contact to have roughened surfaces or friction coatings.

[0020] Further features and advantages of the invention form the subject matter P/25528.GBW of the following description of preferred embodiments and of the depictions of these embodiments in the drawings.

[0021] In the drawings: [0022] Fig. 1 is a perspective view of an embodiment of pressing device. [0023] Fig. 2 is a view from the side of an embodiment of finishing attachment having a pressing device as shown in Fig. 1.

[0024] Fig. 3 is a view from the side of a further embodiment of finishing attachment, showing a pressing device in a state where it is pressed against a workpiece of quite small diameter.

[0025] Fig. 4 shows the finishing attachment shown in Fig. 3 with the pressing device pressed against a workpiece of quite large diameter.

[0026] Fig. 5 is a perspective view of a further embodiment of pressing device. [0027] Fig. 6 is a view from the side of a supporting bearing surface of the pressing device shown in Fig. 5.

[0028] Fig. 7 is a perspective view of a further embodiment of pressing device. [0029] Fig. 8 is a view from the side of a supporting bearing surface of a further embodiment of pressing device.

[0030] Fig. 9 is a perspective view of a further embodiment of pressing device. [0031] Fig. 10 is a longitudinal section through the pressing device shown in Fig. 9.

[0032] Fig. 11 is a perspective view of a further embodiment of finishing attachment having a pressing device.

[0033] Fig. 12 is a perspective view of a further embodiment of finishing attachment having a pressing device.

[0034] An embodiment of pressing device is shown in Fig. 1 and is identified there as a whole by reference numeral 10. The pressing device 10 shown in Fig. 1 is used for the finishing attachment shown in Fig. 2 which is identified as a whole by reference numeral 12.

[0035] The pressing device 10 comprises a holder 14 and this is part of an arm for pressing into contact 16 which is mounted to be pivotable about an axis 18 of the arm for pressing into contact.

[0036] The holder 14 comprises a main portion 20 having two holding arms 22 which project from the main portion 20. The main portion 20 and the P/25528.GBW holding arms 22 together form a U-shaped boundary of a receiving space 24 for a supporting member 26 to be arranged in.

[0037] The supporting member 26 is connected to the holder 14 by means of a pivot shaft defining an axis of pivot 28 and is mounted thereon to be pivotable. To define a basic position of the supporting member 26 relative to the holder 14, two springs 30 are provided which are arranged on either side of the axis of pivot 28, which two springs 30 are arranged between the main portion 20 of the holder 14 and a rear face 32 of the supporting member 26.

[0038] In its front face (unreferenced) remote from the holder 14, the supporting member 26 has a recess 34 which serves to receive at least part of a portion 36 of a workpiece.

[0039] The portion 36 of the workpiece has a cylindrical circumferential surface 38 which is for example a main journal or a connecting-rod journal of a crankshaft. In the event of the circumferential surface 38 being a main journal of a crankshaft, the circumferential surface 38 rotates about a workpiece axis of rotation 40 during a finish-machining operation. A rotary drive which is known per se and is therefore not shown is provided for this purpose. During the finish-machining of the circumferential surface 38, the movement of the workpiece in rotation has an oscillatory movement superimposed on it. This oscillatory movement is indicated in Fig. 1 by a double-headed arrow 42; in the course of it, the portion 36 of the workpiece is moved to and fro relative to a finishing tape 44 (see Fig. 2), parallel to the axis of rotation 40 of the portion 36 of the workpiece. This produces a cross-hatched structure on the surface of the circumferential surface 38 which is characteristic of finish-machining. To produce the oscillatory movement 42, it is possible for the finishing tape 44 and/or the portion 36 of the workpiece to be moved to and fro in a direction parallel to the axis of rotation 40 of the portion 36 of the workpiece. Oscillatory drives which are known per se and therefore require no further explanation are available to produce the oscillatory movement 42.

[0040] During the machining of the portion 36 of the workpiece, the finishing tape 44 is pressed into contact with the circumferential surface 38 over an P/25528.GBW engaged angle 46 (see Fig. 1). For greater clarity, the finishing tape 44 is not shown in Fig. 1. A pressing tape 48 is used to press the finishing tape 44 into contact with the circumferential surface 38. The pressing tape 48 is for example a metal tape which may be relatively thin, the thickness of its material being for example between 0.2 mm and approximately 1.5 mm.

[0041] The pressing tape 48 has ends remote from one another which are fastened to respective ones of the arms for pressing into contact 22, by means of screwed or bolted connections 50 for example.

[0042] The supporting member 26 has two supporting bearing surfaces 52 which are arranged on either side of the engaged angle 46 and which take the form of, in particular, rounded elevations. The supporting bearing surfaces 52 support the pressing tape 48 at supported portions 54 which are limited locally in the direction defined by the tape. Provided between the supported portions 54 in the direction defined by the tape is a free, unsupported pressing portion 56 of the pressing tape for pressing into contact. Provided outside the supported portions 54 in the direction defined by the tape are free unsupported portions 58 of tape.

[0043] In the region of the supported portions 54, the pressing tape 48 has applied to it, by means of the supporting bearing surfaces 52, first and second pressures which are directed in a direction away from the main portion 20 of the holder 14. In the region of the engaged angle 46, the finishing tape exerts on the pressing tape 48 a third pressure which is directed in a direction towards the main portion 20 of the holder 14 and which, in terms of size, is equal to the sum of the first and second pressures.

[0044] The fact of the supporting member 26 being pivotably mounted on the holder 14 about the axis of pivot 28 has the advantage that a movement of the arm for pressing into contact 16 about the axis 18 of the arm for pressing into contact (see Fig. 2) is not converted directly into an identical movement of the pressing tape 48; instead a further degree of freedom around the axis of pivot 28 becomes available, thus making the supporting member 26 pivotable about the axis of pivot 28. In Fig. 2, the supporting member 26 is shown in a corresponding position in which it is deflected P/25528.GBW relative to the basic position shown in Fig. 1.

[0045] The facility for evening-up which has been described above will be explained below by reference to further embodiments of pressing devices 10 and finishing attachments 12 as shown in Figs. 3 and 4. The pressing devices 10 of the finishing attachment 12 shown in Figs. 3 and 4 are likewise suitable for machining workpiece portions 36 of different sizes, such for example as for machining relatively small portions 36a of workpieces (see Fig. 3) and relatively large portions 36b of workpieces (see Fig. 4).

[0046] Whereas pressing devices 10 which face one another are spaced relatively close together when machining a relatively small portion 36a of a workpiece (see Fig. 3), this spacing becomes larger when a relatively large portion 36b of the workpiece is being machined (see Fig. 4). Whereas the supporting member remains in its basic position relative to the holder 14 or close thereto when a relatively small portion 36a of the workpiece is being machined, the supporting member 26 pivots to the deflected position shown in Fig. 4 when a relatively large portion 36b of the workpiece is being machined.

[0047] Unlike the holder 14 shown in Figs. 1 and 2, which is an integral part of the arm for pressing into contact 16, the holders 14 of the pressing devices 10 shown in Figs. 3 and 4 are provided separately from the arm for pressing into contact 16. The holders 14 shown in Figs. 3 and 4 likewise comprise a main portion 20 and holding arms 22 to form the boundary of a receiving space 24 for the supporting member 26.

[0048] The holder 14 shown in Figs. 3 and 4 is solidly connected to the two-pronged arm 16 by an additional screwed or bolted connection 60, using in particular the main portion 20 of the holder 14.

[0049] There will be described below, by reference to Figs. 5 to 8, embodiments of pressing device which are of comparable construction to the pressing devices 10 which were described above by reference to Figs. 1 to 4. It will therefore be only the differences from the pressing devices 10 already described which will be gone into below.

[0050] The pressing devices 10 shown in Figs. 5 to 8 have supporting bearing P/25528.GBW surfaces 52 which are elastically yielding. What may be used for this purpose are support-providing members 62 which are curved in an arc in the region of the supporting bearing surfaces 52 and which are connected to the supporting member 26 to be immovable. The support-providing members 62 are made of an elastomer for example, and in particular of Vulkollan. The support-providing members 62 preferably extend over an angle which is greater than 90° and which is for example 1800.

[0051] In addition to or alternatively to pressing members 62 in a slab form or arcuate form (see Fig. 5 and 6), what may also be used are substantially cylindrical pressing rollers 64 (see Figs. 7 and 8). These are preferably made of an elastomer and in particular of Vulkollan. The pressing rollers may be held immobile on the supporting member 26 (see for example Fig. 7, where the pressing rollers 64 are pressed into receptacles 65). As an alternative to this however, the pressing rollers 64 may equally well be mounted on the supporting member 26 to be rotatable about a roller axis 66 (see Fig. 8).

[0052] The pressing tapes 48 which are described above and below by reference to various pressing devices 10 and finishing attachments 12 may be of a smooth form on their front faces adjacent to the rear faces of finishing tapes 44. When this is the case, a pressing area 66 of the pressing portion 56 of the pressing tape 48 is just as smooth as the frictional areas 68 of the supporting portions 54 of the pressing tape 48 at the points where the supporting bearing surfaces 52 are situated. This being the case, static friction between the area for pressing into contact 66 and the rear face of a finishing tape 44 is just as great as the static friction between the frictional areas 68 of the pressing tape 48 and the rear face of the finishing tape 44.

[0053] In a further embodiment of the invention, provision is made for the frictional areas 68 to be roughened at the points where the supporting bearing surfaces 52 are situated or to have a rough-surfaced coating 70 at those points, see Figs. 6 and 8.

[0054] The areas for pressing into contact 66 of the portion for pressing into contact 56 are in particular smooth and free of roughening and/or of P/25528.GBW coatings 70. It is however also conceivable for the pressing tape 48 also to be roughened and/or provided with a coating 70 in the region of the area for pressing into contact 66.

[0055] In addition to or as an alternative to the roughening described above of a pressing tape 48 on its front face in the region of the frictional areas 68, it is also possible for the pressing tape 48 to be provided with an appropriate roughening or an appropriate coating 70 on its rear face and/or for the supporting bearing surfaces 52 themselves to be provided with such a roughening or such a coating 70. The latter then co-operates with the rear face of the pressing tape 48 (see Figs. 6 and 8, reference numeral 72). The roughenings or coatings 72 may be arranged directly on the body forming the supporting member 26 (such for example as on a supporting member 26 as shown in Fig. 1), or else, as shown in Figs. 6 and 8, on support-providing members 62 or supporting rollers 64, which are made in particular of an elastomeric material.

[0056] All the pressing devices 10 and finishing attachments 12 which are described above have axes of pivot 28 for the supporting member 26 which extend parallel to the axis of rotation 40 of a portion 36 to be machined of a workpiece. These axes of pivot are axes of tilt which thus make it possible for the supporting member 26 to be "tipped" or tilted.

[0057] In addition to or alternatively to this, it is also possible for the supporting member 26 to be mounted to swing about an axis of swing 74, with the axis of swing 74 extending perpendicularly to an axis of rotation 40 of the portion 36 to be machined of a workpiece (see Figs. 9 and 10). The term "perpendicular" which has been adopted in this connection does not imply that the axis of rotation 40 and the axis of swing 74 have to intersect one another; said axes may also be spaced away relative to one another over the range of a very small distance.

[0058] When an axis of swing 74 is used, it is for example possible for the holding arms 22 of the holder 14 to be provided with mounting pins 76 which penetrate into pin receptacles 78 in the supporting member 26. It is preferable for inner faces 80 which face one another of the holding arms 22 to act as guiding surfaces for outer faces 82 of the supporting member P/25528.GBW 26.

[0059] Described below are forms of pressing tape and in particular possible ways of fastening in place a pressing tape and these are advantageous even in their own right and can in particular even be used in pressing devices whose supporting members do not have an axis of pivot (i.e. pressing devices as claimed in claim 1 but with the exception of the feature that the supporting member has an axis of pivot).

[0060] Described below by reference to Figs. 11 and 12 are possible ways of fastening in place pressing tapes 48 of pressing devices 10, which ways of fastening in place are suitable for supporting members 26 which have axes of pivot 28 and/or 74 as described above (or which even do not have an axis of pivot and which may be solidly connected to a two-pronged arm 16).

[0061] At one end, a pressing tape 48 may for example be connected, and in particular may be screwed or bolted (see Fig. 11), to the supporting member 26 by means of a connecting means 50 and at the other end it may be fastened to the two-pronged arm 16 (and in particular to the latter's inner face facing towards the two-pronged arm 16 situated opposite) by means of a connecting means 84 and preferably by means of a screwed or bolted connection.

[0062] In the embodiment shown in Fig. 11 there are two pressing devices 10 provided, each having a pressing tape 48 of its own.

[0063] It is also possible for a pressing tape 48 to be used which is connected, and in particular screwed or bolted (see Fig. 12), by a free end, particularly by using a connecting means 50, to a supporting member 26 of a first pressing device 10, and whose other end is connected, and in particular screwed or bolted, by means of a connecting means 50, to the supporting member 26 of a second pressing device 10. A pressing tape 48 of this kind which is used for two pressing devices 10 at the same time preferably has its direction changed around a direction-changing shaft 88 at a direction-changing means 86 arranged between the two pressing devices 10.

Claims

P/25528.GBW Claims 1. Pressing device (10) having a pressing tape (48) for pressing finishing tape (44) into contact with circumferential surfaces (38) of substantially cylindrical portions (36) of workpieces in a finish-machining operation in such a way that the finishing tape (44) is pressed into contact with a circumferential surface (38) with a force for pressing into contact over an engaged angle (46), characterised in that the pressing tape (48) is supported on two supporting bearing surfaces (52) which are arranged on either side of the engaged angle (46) and which belong to a supporting member (26) having at least one axis of pivot (28).
2. Pressing device (10) according to claim 1, characterised in that the pressing tape (48) has on both sides of the supporting bearing surfaces (52), looking in the direction defined by the tape, free portions (56, 58) which are not supported.
3. Pressing device (10) according to either of the preceding claims, characterised in that the supporting bearing surfaces (52) are made of an elastically yielding material and in particular from an elastomer.
4. Pressing device (10) according to one of the preceding claims, characterised in that the pressing tape (48) is fastened to a holder (14) provided separately from the supporting member (26).
5. Pressing device (10) according to claim 4, characterised in that the supporting member (26) is pivotable relative to the holder (14) about the at least one axis of pivot (28).
6. Pressing device (10) according to one of the preceding claims, characterised in that the holder (14) has a receiving space (24) for the supporting member (26) to be arranged in, which receiving space (24) has a U-shaped boundary.
7. Pressing device (10) according to one of claims 4 to 6, characterised in that the holder (14) is connected to an arm for pressing into contact (16) or is part of the arm for pressing into contact (16) and in that the arm for pressing into contact (16) is pivotable about an axis (18) of the arm for pressing into contact.
8. Pressing device (10) according to one of the preceding claims, characterised in that what is provided as at least one axis of pivot (28) is an axis of tilt which P/25528.GBW extends relative to a workpiece to be machined in a direction parallel to the axis of rotation (40) of the workpiece.
9. Pressing device (10) according to one of the preceding claims, characterised in that what is provided as at least one axis of pivot (28) is an axis of swing (74) which extends relative to a workpiece to be machined in a direction perpendicular to the axis of rotation (40) of the workpiece.
Pressing device (10) according to one of the preceding claims, characterised in that the pressing tape (48) has frictional areas (68) at the points where the supporting bearing surfaces (52) are situated, in that the pressing tape (48) has an area for pressing into contact (66) between the supporting bearing surfaces (52) in the region of the engaged angle (46), and in that the static friction between the frictional areas (68) of the pressing tape (48) and a rear face of the finishing tape (44) is higher than the static friction between the area for pressing into contact (66) of the pressing tape (48) and the rear face of the finishing tape (44).
11. Pressing device (10) according to claim 10, characterised in that the roughness of the frictional areas (68) is higher than that of the area for pressing into contact (66).

12 Pressing device (10) according to one of the preceding claims, characterised in that the supporting bearing surfaces (52) have roughened surfaces or friction coatings (72) which co-operate with a rear face of the pressing tape (48) which is remote from the finishing tape (44) and/or in that the rear face of the pressing tape (48) has roughened surfaces or friction coatings (72).