Method for Producing Drive Belts

Abstract

The invention relates to a method for producing drive belts from different materials by means of casting processes. To this end, a mould core and an outer mould of a casting tool are provided. The circumferential surface of the mould core or the inner circumferential surface of the outer mould is provided with a geometry to be represented on the drive belt. A textile layer is laid on the geometry. The mould core is set into the outer mould so that the mould core and the outer mould define a cavity between them. Optionally, a tension member can be arranged in the cavity and the cavity can be sealed with respect to the environment at least in the region of the geometry to be represented on the drive belt. The textile layer is applied to the surfaces defining the geometry and an elastomer base material is introduced into the cavity.

Claims

1.-19. (canceled)

20. A method for producing a drive belt, comprising: a) providing a mould core and an outer mould of a casting tool, wherein the mould core is provided to be inserted into the outer mould such that a cavity representing a shape of the drive belt to be produced is formed between the outer mould and the mould core sitting therein, and wherein a circumferential surface of the mould core assigned to the cavity or the inner circumferential surface of the outer mould assigned to the cavity is provided with a geometry to be represented on the drive belt which is formed by recesses or protrusions which are delimited by surfaces abutting one another which are formed into the circumferential surface of the mould core or the inner circumferential surface of the outer mould or formed on the circumferential surface of the mould core or the inner circumferential surface of the outer mould; b) placing a textile layer on the geometry to be represented on the drive belt; c) inserting the mould core into the outer mould so that the mould core and the outer mould define the cavity between them; d) optionally arranging a tension member in the cavity; e) optionally sealing the cavity at least in a region of the geometry to be represented on the drive belt with respect to the environment; f) applying the textile layer on the surfaces which delimit the geometry to be represented on the drive belt on the mould core or on the outer mould, wherein applying the textile layer on the geometry (work step f)) is supported by generating an underpressure in a region of the free spaces which are present between the textile layer and the geometry after work step b); g) introducing a castable elastomer base material into the cavity; h) optionally pressing base material after completely filling the cavity with the base material to effect a pressure increase in the cavity; i) optionally maintaining the pressure acting on the base material until the base material has become sufficiently hard; j) demoulding a belt winding obtained; and k) optionally separating the drive belt from the belt winding.

21. The method according to claim 20, wherein the geometry is formed on the circumferential surface of the mould core.

22. The method according to claim 20, wherein the geometry is formed on the inner circumferential surface of the outer mould.

23. The method according to claim 20, wherein the textile of the textile layer is provided with a coating capable of reacting with the base material.

24. The method according to claim 20, wherein the base material is introduced into the cavity with a pressure applied.

25. The method according to claim 20, wherein at least one of the mould core or the outer mould is heated.

26. The method according to claim 20, wherein in work step g) a first base material is introduced into a first area of the cavity and a second base material is introduced into a second area of the cavity, which is distinguished from the first base material in at least one mechanical property in a completely produced drive belt.

27. The method according to claim 20, wherein in order to introduce the tension member into the cavity (work step d)), the tension member is placed around the mould core prior to inserting the mould core into the outer mould (work step c)) and is set together with the mould core into the outer mould.

28. The method according to claim 20, wherein the castable elastomer base material is injected into the cavity in work step g), wherein a tension member is positioned by means of movable auxiliary elements in the cavity of the cast mould at a distance from the textile layer after inserting the mould core into the outer mould and prior to injecting the base material and wherein the auxiliary elements, after injecting a first portion of the base material, are moved out of the cavity step by step or continuously leaving the tension member behind in the base material.

29. The method according to claim 20, wherein the drive belt to be produced is a synchronous belt and wherein the geometry provided on the circumferential surface of the mould core or on the inner circumferential surface of the outer mould assigned to the cavity is a toothed geometry to be represented on the synchronous belt.

30. The method according to claim 28, wherein in work step d) a tension member is placed directly on the textile layer previously placed on the geometry such that said tension member is supported via the textile layer on the toothed end surfaces of the toothed geometry.

31. The method according to claim 20, wherein the tension member is formed as a textile cut-out.

32. The method according to claim 31, wherein threads of the tension member textile cut-out are arranged at an angle in relation to the longitudinal axis of the mould core which is >0 and <90.

33. The method according to claim 31, wherein the tension member textile cut-out is formed in the manner of a hose.

34. The method according to claim 31, wherein the tension member textile cut-out is formed in shape of a strip and is applied to the geometry in one winding or a plurality of windings.

35. The method according to claim 20, wherein the castable elastomer base material is injected into the cavity in work step g) and in that the geometry-side textile layer or the tension member is fixed on regions of the cast mould assigned to end sides of the mould core prior to injecting the base material into the cavity.

36. The method according to claim 20, wherein the tension member or the textile insert comprises a labelling device which clearly identifies the drive belt as a passive element when the completely produced drive belt is used and/or as an active element detects at least one property or at least one state of the drive belt and sends detected information to a signal detection device.

Description

[0109] The invention will be explained further below based on a drawing representing an exemplary embodiment. They schematically show:

[0110] FIG. 1 a casting tool in longitudinal section,

[0111] FIG. 2 the tool according to FIG. 1 in a section along the section line X-X plotted in FIG. 1 and

[0112] FIG. 3 a cut-out A of FIG. 2;

[0113] FIG. 4a a first tension member fabric blank;

[0114] FIG. 4b the fabric blank according to FIG. 4a in a state applied to the core of the casting tool;

[0115] FIG. 5a a second tension member fabric blank;

[0116] FIG. 5b the fabric blank according to FIG. 5a in a state applied to the core of the casting tool;

[0117] FIG. 6a a third tension member fabric blank;

[0118] FIG. 6b the fabric blank according to FIG. 6a in a state applied to the core of the casting tool;

[0119] FIG. 7 a cut-out of a synchronous belt produced according to the invention in a longitudinal section.

[0120] The injection moulding tool 20 has a tubular core 21 and an outer shell 22, the core 21 carrying on its circumference 24 assigned to the cavity 23 of the tool 20 a toothing 25 forming the tooth geometry of the core 21 and the inner surface 26 of the outer shell 22 assigned to the cavity 23 is formed flat.

[0121] The core 21 surrounds a central evacuation line 27. A large number of suction lines 29, 30 are guided through the wall of the core 21 from the central evacuation line 27 to the circumference of the core 21.

[0122] The suction lines 29, 30 discharge into the tooth bases of the tooth geometry provided at the circumferential surface 24 of the core 21 and are, in this case, distributed such that a uniformly distributed underpressure results at the circumferential surface 24 when the atmosphere (air) present in the cavity 23 is suctioned via the central evacuation line 27.

[0123] A textile layer G formed as fabric and a tension member layer Z are inserted into the tool 20 to produce a synchronous belt winding from which a larger number of synchronous belts can subsequently be divided (FIG. 2, 3).

[0124] The textile layer G is arranged such that it is located between the toothing 25 and the tension member layer Z. The length of the textile layer G is dimensioned taking into account its elasticity such that it corresponds to the length of the contour line of the toothing 25, the textile layer G can thus be applied to the toothed circumferential surface 24 of the core 21 such that it can cover the circumferential surface 24 of the core 21 without folds and substantially without stresses.

[0125] The textile layer G is provided with a coating made of a material which is related to the base material B from which the base body of the drive belt to be produced is supposed to be manufactured. If the base material B is, for example, a PU material, the coating of the textile layer G also expediently consists of a PU material. In this way, the base material B reacts with the coating material of the textile layer G when the base material B is introduced into the cavity 23 and an intensive materially-bonded binding results between the base body formed from the base material B and the textile layer G of the drive belt. The coating of the textile layer G can be carried out such that the individual fibres, of which the textile layer G consists, are provided with the coating or the textile layer G as a whole is provided with a coating. In the latter case, the coating is optimally formed such that the textile layer G is as gas-tight as possible in order to support the application on the geometry to be represented on the drive belt (toothing 25).

[0126] As represented in FIG. 3, the tension member layer Z is supported via the textile layer G on the tooth end surfaces of the toothing 25 (tooth geometry) in the configuration explained here such that no further retaining means are required to position the textile layer G in the cavity 23.

[0127] However, if the tension member layer Z is supposed to be positioned in the free space between the toothing 25 and the inner surface 26 of the outer shell 22, retaining elements, not represented here, can be inserted here for this purpose. The tension member layer Z can be held in the cavity 23 by means of these retaining elements such that its position corresponds to the target position in the synchronous belt winding to be produced.

[0128] The tension member layer Z is for example a winding, which is formed by winding individual tension member fibres or tension member fibre strands. Alternatively, the tension member layer Z may be a fabric blank ZZ1-ZZ3, as is explained further below in connection with the FIGS. 4a-6d.

[0129] After positioning the tension member Z and the textile G, the cavity 23 is sealed by means of a lid 33 which also covers the central evacuation line 27 and has a central suction opening 37 via which the evacuation line 27 and thus the cavity 23 can be evacuated via the suction lines 29, 30. For this purpose, an evacuation device, not shown here, is connected to the suction opening.

[0130] The mould core 21 and the outer shell 22 sit on a base 34 on the side opposite the lid 33, said base seals the cavity 23 and the central evacuation line 27 at this side. Injection nozzles 35, 36 are guided through the base 34 by means of which base material B can be injected into the cavity 23.

[0131] In order to prevent slipping of the textile layer G during injection of the base material into the cavity on the toothing 25 of the core 21, the textile layer G can be fixed in the region of the end sides of the core 21.

[0132] If the cavity 23 is now evacuated via the central evacuation line 27, the textile layer G is suctioned at the predefined tooth contour of the toothing 25 such that the textile G assumes the predefined tooth shape (FIG. 3). The textile G is held and pre-stretched by the vacuum such that it abuts on the tooth geometry of the mould core 21.

[0133] Only then does the actual casting process begin. In this case, a first batch of the base material B is injected via the base 34 of the tool into the cavity 23 and in such a way that the tension member layer Z is carried by the injected base material B. Air still present in the cavity 23 and displaced by the base material B can escape via separate air outlets 38, 39.

[0134] In the event that retaining elements have been used to position the textile layer G, these are now drawn out of the cavity 23 and, if necessary, an additional batch of the base material B is injected into the cavity 23.

[0135] If the cavity 23 is thereby completely filled, the air outlets 38, 39 are sealed. Optionally, a short pressure increase can now be effected. The base material B injected (pressed) with increased overpressure ensures the complete forming of the toothing with textile G and base material B. The air possibly still present between textile G and the tooth geometry can escape via the suction lines 29, 30. The contact of the textile layer G on the surfaces of the toothing 25 assigned thereto is thus perfected and the filling of the cavity 23 similarly optimised.

[0136] As already explained above, the tension member Z can also be provided as a fabric blank and be arranged in the cavity 23 of the casting tool 20. The tension member fabric blank can be formed as a hose structure or, as shown in FIGS. 4a-6d, be processed as blank ZZ1, ZZ2, ZZ3 provided from a flat textile fabric.

[0137] In the case of the variant represented in FIG. 4a, 4b, the tension member fabric blank ZZ1 has a rectangular shape whose height H corresponds to the height of the core 21 and whose length L corresponds to the circumferential length of the maximum circular diameter of the core 21 defined by the tooth end surfaces of the toothing 25 provided on the core 21 and the textile layer G located thereon. The fabric blank ZZ1 can accordingly be placed around the core 21 such that it, on the one hand, rests tightly on the sections of the textile layer G located on the tooth end surfaces of the toothing 25 and, on the other hand, is joined with its edges 60, 61 connecting its longitudinal sides by an edge joint. The joint line 62 is aligned axially parallel to the longitudinal axis LX of the core 21.

[0138] As cut-out B of FIG. 4a shows in an enlargement, the threads or fibres of the fabric blank can be aligned at an angle of, for example, 45 in relation to the longitudinal axis LX in order to give the tension member fabric blank ZZ1 a certain extensibility in the circumferential direction U of the core 21 and therefore give the synchronous belt to be produced a corresponding extensibility. In this case, weft threads S of the fabric blank ZZ1 absorbing the tensile forces loaded on the synchronous belt consist of a high-performance fibre, such as aramid, whereas the warp threads K of the fabric blank ZZ1, which merely ensure the position of the weft threads S, are formed from comparably weak polyester fibres.

[0139] In the case of the variant shown in FIG. 5a, 5b, the tension member fabric blank ZZ2 has the shape of a tilted parallelogram whose height H corresponds to the height of the core 21 and whose length L, in turn, corresponds to the circumferential length of the maximum circular diameter of the core 21 defined by the tooth end surfaces of the toothing 25 provided on the core 21 and the textile layer G located thereon. The fabric blank ZZ2 can also accordingly be placed around the core 21 such that it, on the one hand, rests tightly on the sections of the textile layer G located on the tooth end surfaces of the toothing 25 and, on the other hand, is joined with its edges 63, 64 connecting its longitudinal sides by an edge joint. The joint line 65, in this case, runs in a straight line aligned inclined in relation to the longitudinal axis LX of the core 21 from upper 66 to the lower end side 67 of the core 21.

[0140] As cut-out C of FIG. 5b shows in an enlargement, the threads or fibres are aligned at an angle of 0 or 90 in relation to the longitudinal axis LX in the blank ZZ2 in order to give the tension member fabric blank ZZ2 maximum tensile strength.

[0141] In the case of the variant shown in FIG. 6a, 6b, the tension member fabric blank ZZ3 formed here in a strip shape also has the form of a tilted parallelogram. However, its height H corresponds, for example, only to a fraction, for example one fifth, of the height of the core 21. Its length L is also dimensioned such that the fabric blank ZZ3 can be repeatedly wound in a spiral shape around the textile layer G located on the core 21 starting from the edge of the core 21 assigned to the lower end side 67 until it ends at the edge of the core 21 assigned to the upper end side 66. In this case, the longitudinal edges of the fabric blank ZZ3 abut one another tightly in a joint line 68 circulating in a spiral shape around the core 21 and are also aligned inclined in relation to the longitudinal axis LX of the core 21.

[0142] The connection between the edges of the tension member fabric blanks ZZ1, ZZ2, ZZ3 respectively laid around the core 21 respectively abutting in the joint lines 62, 65 and 68 is carried out, for example, by welding by means of a laser.

[0143] As a result, a synchronous belt winding is obtained with the invention which has an optimal surface quality free of undesired indents and the like whilst also having optimal property distribution.

[0144] Synchronous belts ZR are, in a manner known per se, divided from the synchronous belt winding obtained, whose width corresponds to the respective customer requirements.

[0145] Synchronous belts ZR produced according to the invention are characterised in that when they are in the brand-new state, the textile layer G is freely, i.e. not covered by an auxiliary film of base material, arranged on the inside ZI of the synchronous belt ZR provided with the tooth geometry ZG. In this case, the tooth base ZB respectively present between the adjacent teeth ZZ of the tooth geometry ZG is uniform and notch-free although the tension member Z is located directly on the textile layer G here.

LIST OF REFERENCE NUMERALS

[0146] 20 injection moulding tool [0147] 21 tubular core (mould core) [0148] 22 outer shell (outer mould) [0149] 23 cavity of the tool 20 (circumferential surface) [0150] 24 tooth geometry of the core 21 [0151] 25 toothing 25 forming the tooth geometry [0152] 26 inner surface of the outer shell 22 [0153] 27 central evacuation line [0154] 29, 30 suction lines [0155] 33 lid [0156] 34 base [0157] 35, 36 injection nozzles [0158] 37 central suction opening [0159] 38, 39 air outlets [0160] 60, 61 edges of the tension member fabric blank ZZ1 [0161] 62 joint line [0162] 63, 64 edges of the tension member fabric blank ZZ2 [0163] 65 joint line [0164] 66 upper end side of the core 21 [0165] 67 lower end side of the core 21 [0166] 68 joint line [0167] B base material [0168] G textile layer [0169] H height of the tension member fabric blanks ZZ1-ZZ3 [0170] K warp threads [0171] L length of the tension member fabric blanks ZZ1-ZZ3 [0172] LX longitudinal axis of the core 21 [0173] S weft threads [0174] Z tension member layer [0175] ZZ1-ZZ3 tension member fabric blanks [0176] ZR synchronous belt [0177] ZG tooth geometry [0178] ZZ teeth [0179] ZB tooth base