Apparatus and method for cutting rubber intermediates

Abstract

The present invention relates to a cutting device for an intermediate product made of rubber, the intermediate product comprising parallel filamentary reinforcing elements embedded in the rubber, the cutting device comprising a support, a blade and a blade holder movable between an open position and a closed position in which the blade contacts the support. According to the invention, the blade is loosely attached to the blade holder such that the blade is pivotable and / or translatable relative to the blade holder.

Description

[Technical field]

[0001] The present invention relates to the field of rubber-based product manufacturing, and more particularly to the field of cutting of intermediate products involved in the manufacture of tires or wheels. [Background technology]

[0002] The manufacture of tires or wheels involves multiple steps of cutting intermediate products of various shapes, generally longitudinal and profile, such as plies or strips obtained by calendering or extrusion processes. The particular intermediate product is preferably based on rubber in the unvulcanized state and comprises mutually parallel filamentary reinforcing elements embedded in the unvulcanized rubber.

[0003] The production of straight cuts in the reinforced intermediate product comprises two variants, depending on whether one wishes to obtain straight cuts parallel to the filamentary reinforcing elements made of raw rubber, or straight cuts forming an angle with the filamentary reinforcing elements, thus cutting them.

[0004] It has been found that obtaining a straight cut according to the first variant is particularly difficult without accidentally cutting adjacent filamentary reinforcing elements, and therefore the cutting means used to make the straight cut are generally designed to be wear-resistant or break-resistant for cutting the filamentary reinforcing elements, which is expensive.

[0005] In order to perform linear cuts parallel to the filamentary reinforcing elements, a method is known which uses a chisel which is inserted into the raw rubber between two filamentary elements on one side of the intermediate product and, with accurate guidance of the chisel ensured by the two filamentary elements, is moved in a direction generally parallel to the filamentary reinforcing elements and pulled out on the other side of the intermediate product.

[0006] Such a method is particularly suitable when it is intended to assemble the intermediate product onto a tire blank using an assembly drum, since cutting can be performed simultaneously with assembly, without introducing any manipulation of the cut intermediate product.

[0007] However, such a method is not suitable when it is intended to mold the intermediate product, since the linear cuts cannot be performed in parallel and introduce one or more operations on the intermediate product that are cut before molding. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, there is a need for a method of cutting reinforced pre-products that overcomes these drawbacks. [Means for solving the problem]

[0009] As a result, the invention proposes a cutting device for intermediate products made of rubber, the intermediate products comprising mutually parallel filamentary reinforcing elements embedded in the rubber, the cutting device comprising a support, a blade and a blade holder movable between an open position and a closed position in which the blade is in contact with the support.

[0010] According to the invention, the blade is loosely attached to the blade holder such that the blade is pivotable and / or translatable relative to the blade holder.

[0011] The blade has a longitudinal direction, a transverse direction and a yaw direction that is substantially parallel to a closing direction of the blade holder, and the blade is pivotable about and / or translatable along one or more of the above directions relative to the blade holder.

[0012] Preferably, the intermediate product is based on raw rubber.

[0013] When the blade holder is in the closed position, the intermediate product is pre-positioned such that its filamentary reinforcing elements are substantially parallel to the longitudinal direction of the blade in the closed position of the blade holder, and the blade penetrates the raw rubber of the intermediate product, forcing it to flow on both sides of the blade, after which, when it is able to contact one of the filamentary reinforcing elements, the blade pivots and / or translates until it can slide over the edge of that reinforcing element and / or until it can push the reinforcing element back.

[0014] Thus, the cutting edge of the blade is subjected to less stress and less wear since the cut is made without severing the filamentary reinforcing elements.

[0015] Preferably, the blade holder comprises a housing in which the blade is mounted and which is capable of limiting the pivoting and translational movement of the blade.

[0016] The magnitude of the pivoting and translating of the blade makes it possible to compensate for the lack of parallelism between the filamentary reinforcing elements and the longitudinal direction of the blade in the closed position of the blade holder, this parallelism being less than or equal to the pitch spacing of the filamentary reinforcing elements.

[0017] As an example, the blade is rotatable about said direction by angles in the range of plus or minus 2.5° relative to the position where the blade is centrally located on the housing, and is translatable along said direction by distances in the range of plus or minus 2.5 mm.

[0018] As an example, the pitch spacing of the filamentary reinforcing elements is 0.5 to 10 mm.

[0019] Advantageously, the blade is only translatable along the yaw direction relative to the blade holder, and other movement possibilities of the blade relative to the blade holder are substantially precluded.

[0020] In other words, the possibilities for relative movement of the blade with respect to the blade holder other than translation along the yaw direction are greatly limited.

[0021] As an example, the blade is strongly constrained from rotation about the relevant direction by an angle in the range of plus or minus 0.25° relative to the position where the blade is located at the center of the housing, and strongly constrained from translation along the relevant direction by a distance in the range of plus or minus 0.25 mm.

[0022] By way of example, the magnitude of the blade translation along the yaw direction ranges from 0.5 mm to 10 mm.

[0023] In this way, the structure of the cutting device is optimized while maintaining efficient operation.

[0024] Advantageously, the cutting device comprises elastic means arranged between the blade and the blade holder.

[0025] When the blade is able to contact one of the filamentary reinforcing elements, the blade is secured and the blade holder continues to move towards the closed position by compressing the elastic means, when the elastic means exerts sufficient stress on the blade, the blade pushes back against the reinforcing element and slides over its edge.

[0026] The cut is therefore made cleanly and burr-free.

[0027] Preferably, in the closed position of the blade holder, the elastic means exerts a stress on the blade sufficient to allow the blade to slide between the two filamentary reinforcing elements by causing the raw rubber to flow, but this stress is less than the closing stress applied to the blade holder and / or a stress that could break one of the filamentary reinforcing elements.

[0028] Sufficient stress depends in particular on the shape and orientation of the blade, the physical properties of the raw rubber, the thickness of the intermediate product, the length of the cut, the pitch and the diameter of the filamentary reinforcing elements.

[0029] As an example, the filamentary reinforcing elements have a diameter of 0.2 to 5 mm.

[0030] Advantageously, the support has a notch into which the blade is inserted when the blade holder is in the closed position.

[0031] Thus, the cutting edge of the blade is not directly supported by the bearing support and is therefore subjected to less stress and less wear.

[0032] The present invention also relates to a hardening mold for an intermediate product, comprising at least one cutting device according to the previous subject matter of the invention and at least two moulding cavities for the cut intermediate products, the cutting device being arranged such that the open position of the cutting device corresponds to the open position of the hardening mold and the closed position of the cutting device corresponds to the closed position of the hardening mold.

[0033] Preferably, the mold comprises upper and lower portions that join along a contour when the mold is in the closed position, the contour dividing each mold cavity. The upper side of the mold includes the upper portion of the cavity, the blade holder and the blade. The lower side of the mold includes the lower portion of the cavity and the support.

[0034] When the curing mold is in the closed position, a cutting device cuts the intermediate product, which is pre-positioned in the curing mold with its filamentary reinforcing elements substantially parallel to the longitudinal direction of the blade, and the cut intermediate product is cured in each of the molding cavities.

[0035] In this way, the intermediate product is cut in parallel during the closing of the mold and the cutting method according to the invention, unlike prior art cutting and hardening devices, does not introduce one or more manipulations of the cut intermediate product before molding.

[0036] Preferably, the elastic means exerts sufficient stress on the blade to enable it to slide between the two filamentary reinforcing elements by causing the raw rubber to flow, and the intermediate product is subjected to a given molding pressure when the mold is in the closed position.

[0037] The molding pressure depends, inter alia, on the shape of the cavity for the intermediate product, the viscosity of the raw rubber, the volume and orientation of the braids, and the pitch and diameter of the filamentary reinforcing elements.

[0038] As an example, the molding pressure in the mold ranges from 1 to 50 bar.

[0039] Advantageously, in the closed position of the mould, the blades form the separations between the cavities.

[0040] The sidewall of the blade thus forms part of the forming surface of the curing mold.

[0041] Advantageously, the blade has a thickness of less than or equal to 2 mm, preferably less than or equal to 1 mm.

[0042] Thus, the stress sufficient to allow the braid to slide between the two filamentary reinforcing elements is limited.

[0043] Additionally, the cross section of the blade is limited, reducing the stresses the blade experiences due to molding pressure.

[0044] Advantageously, the curing mould comprises means for positioning the intermediate product.

[0045] Preferably, the positioning means is formed by a lower division of the cavity.

[0046] The positioning means therefore make it possible to rapidly position the intermediate product on the support so that, in the closed position of the blade holder, its filamentary reinforcing elements are substantially parallel to the longitudinal direction of the blade.

[0047] The present invention also relates to a method for molding a rubber intermediate product using a curing mold according to the previous subject of the invention, said method comprising the steps of: - positioning the intermediate product on a support so that the filamentary reinforcing elements are substantially parallel to the longitudinal direction of the blade in the closed position of the mould; placing the blade holder in a closed position; Includes.

[0048] In this way, the intermediate product can be approximately positioned such that the blade, in the closed position of the blade holder, can compensate for any lack of parallelism between the filamentary reinforcing elements and the longitudinal direction of the blade.

[0049] Advantageously, prior to the step of positioning the intermediate product, the intermediate product is pre-cut.

[0050] The blade is guided by the precut in the intermediate product, making cutting easier.

[0051] Additionally, less rubber is required to flow on either side of the blade, reducing the volume of intermediate product, thereby reducing stress on the blade.

[0052] The invention will be better understood from the remaining description on the basis of the following figures. [Brief description of the drawings]

[0053] [Figure 1] FIG. 2 is a simplified diagram of certain elements of a cutting device according to the invention in an open position. [Diagram 2] 2 is a simplified diagram of certain elements of a cutting device according to the present invention moving towards a closed position. [Diagram 3] FIG. 1 is a longitudinal cross-section of the present invention according to a preferred embodiment. [Figure 4] FIG. 1 is a longitudinal cross-section of the present invention according to a preferred embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] In the various figures, identical or similar elements are provided with the same reference numbers, so their description will not be repeated systematically.

[0055] Figures 1 and 2 show a device 10 for cutting an intermediate product 12 comprising raw rubber, the intermediate product comprising filamentary reinforcing elements 14 embedded in the rubber and parallel to one another. By way of example, the filamentary reinforcing elements are synthetic or metallic, their diameter is in the range of 0.2-5 mm and the spacing pitch P of the filamentary reinforcing elements is in the range of 0.5-10 mm. The cutting device 10 comprises a support 16, a blade 18 and a blade holder 20 movable between an open position and a closed position in which the blade contacts the support. The thickness of the blade 18 is less than or equal to 2 mm, and preferably less than or equal to 1 mm.

[0056] The blade 18 is loosely attached to the blade holder 20 such that the blade is pivotable and / or translatable relative to the blade holder. The blade has a longitudinal direction 22, a transverse direction 24, and a yaw direction 26 that is substantially parallel to a closing direction 28 of the blade holder. The blade is pivotable about and / or translatable along one or more of said directions relative to the blade holder. The blade holder includes a housing 30 in which the blade is attached, which may limit the pivoting and translation of the blade. The blade 18 is connected to the blade holder 20 by any suitable means (not shown). By way of example, the blade may be connected to the blade holder by a rivet that is fixed to the blade holder and that passes loosely through a hole in the blade.

[0057] According to a preferred embodiment of the invention shown in Figures 3 and 4, the blade 18 is only translatable along the yaw direction 26 relative to the blade holder 20. The blade is attached to the blade holder with a suitable fit, allowing it to slide freely in the housing 30 and thus form a sliding connection with the blade holder. By way of example, the blade 18 can slide along the yaw direction 26 with a magnitude ranging from 0.5 mm to 10 mm. Any other possible movements of the blade relative to the blade holder are practically excluded. In other words, the possible relative movements of the blade to the blade holder other than the translatable movement along the yaw direction are significantly limited. By way of example, the blade is strongly restricted in rotation around a direction relating to an angle in the range of plus or minus 0.25° and in translation along a direction relating to a distance in the range of plus or minus 0.25 mm with respect to the position where the blade is located in the center of the housing.

[0058] The cutting device comprises elastic means 32 arranged in a housing 30 between the blade 18 and the blade holder 20. By way of example, the elastic means can take the form of a spiral spring or a stack of elastic washers. In the closed position of the blade holder 20, the elastic means 32 exerts a sufficient stress on the blade 18 to allow the blade to slide between the two filamentary reinforcing elements 14 by causing the raw rubber to flow, but this stress is smaller than the closing stress applied to the blade holder and / or the stress that would be able to cut one of the filamentary reinforcing elements 14. The sufficient stress depends, inter alia, on the shape and orientation of the blade, the physical properties of the raw rubber, the thickness of the intermediate product, the length of the cut, the pitch and the diameter of the filamentary reinforcing elements.

[0059] 3 and 4 also show a curing mould 34 for the intermediate product 12, comprising at least one cutting device 10 and at least two cavities 38 for shaping the cut intermediate product. The cutting device 10 is arranged such that the open position of the cutting device corresponds to the open position of the curing mould and the closed position of the cutting device corresponds to the closed position of the curing mould. In the closed position of the curing mould 34, the blade 18 forms a separation between each of the cavities 38. In other words, the side walls of the blade form part of the shaping surface of the curing mould. The support 16 has a notch 36 into which the blade 18 is inserted when the blade holder 20 is in the closed position. The curing mould 34 comprises means for positioning the intermediate product formed by the underside of the cavities 38.

[0060] The curing mould 34 comprises an upper part 40 and a lower part 42 which join along a contour 44 when the curing mould is in the closed position, said contour dividing each cavity 38. The upper part 40 of the curing mould comprises the upper part of the cavity, the blade holder 20 and the blade 18. The lower part 42 of the curing mould comprises the lower part of the cavity and the support 16. The elastic means 32 exert a sufficient stress on the blade 18 and cause the raw rubber to flow, thereby allowing the blade to slide between the two filamentary reinforcing elements 14, so that the intermediate product 12 is subjected to a given moulding pressure when the curing mould 34 is in the closed position. The moulding pressure depends in particular on the shape of the cavity relative to the intermediate product 12, the viscosity of the raw rubber, the volume and orientation of the blade 18, the pitch and the diameter of the filamentary reinforcing elements 14. By way of example, the moulding pressure in the mould 34 ranges from 1 to 50 bar.

[0061] The method for molding the rubber intermediate product 12 using the curing mold 34 includes the following steps: Optionally, pre-cutting the intermediate product 12; positioning the intermediate product 12 on the support 16 by means of positioning means such that the filamentary reinforcing elements 14 are substantially parallel to the longitudinal direction 22 of the blades 18 in the closed position of the curing mold; placing the blade holder 20 in a closed position; Includes.

[0062] When the blade holder 20 is in the closed position, the blade 18 penetrates the raw rubber of the intermediate product 12, forcing it to flow on both sides of the blade. Then, when it is able to contact one of the filamentary reinforcing elements 14, the blade pivots and / or translates until it can slide over the edge of that element and / or push the element back.

[0063] According to a preferred embodiment of the invention, when the blade 18 is able to contact one of the filamentary reinforcing elements 14, the reinforcing element is fixed and the blade holder 20 continues its movement towards the closed position by compressing the elastic means 32. When the elastic means exerts sufficient stress on the blade, the blade pushes back said element 14 and then slides over its edge.

[0064] The intermediate product 12 is cut during closing of the mold 34. The cut intermediate products are then hardened in each of the moulding cavities 36.

[0065] Other variations and embodiments of the invention can be envisaged without departing from the scope of the claims. [Explanation of symbols]

[0066] 10 Disconnecting Device 12 Intermediate products 14 Filamentary reinforcing elements 16 Support 18 Blades 20 Blade holder 22 Longitudinal 24 Transverse 26 Yaw direction 28 Closing direction

Claims

1. A cutting device (10) for rubber intermediate products (12), comprising: The cutting device (10), wherein the intermediate product comprises parallel filamentary reinforcing elements (14) embedded in the rubber, the cutting device (10) comprising a support (16), a blade (18) and a blade holder (20) movable between an open position and a closed position in which the blade contacts the support, The blade (18) is loosely attached to the blade holder (20) such that the blade is pivotable and / or translatable relative to the blade holder. A cutting device comprising:

2. 2. The cutting device of claim 1, wherein the blade (18) is translatable only along a yaw direction (26) relative to the blade holder (20), and other movement possibilities of the blade relative to the blade holder are substantially precluded.

3. 2. A cutting device according to claim 1, comprising elastic means (32) arranged between the blade (18) and the blade holder (20).

4. 2. The cutting device according to claim 1, wherein the support (16) comprises a notch (36) into which the blade (18) is inserted when the blade holder (20) is in the closed position.

5. A curing mold (34) for an intermediate product (12), comprising at least one cutting device (10) according to claim 1 and at least two moulding cavities (38) for the cut intermediate products, The cutting device is arranged such that an open position of the cutting device (10) corresponds to an open position of the hardening mold (34) and a closed position of the cutting device (10) corresponds to a closed position of the hardening mold (34).

6. The hardening mold of claim 5, wherein in a closed position of the hardening mold (34), the blades (18) define separations between the molding cavities (38).

7. A hardening mold according to claim 5, wherein the thickness of the blade (18) is less than or equal to 2 mm, preferably less than or equal to 1 mm.

8. 6. The curing mold of claim 5, including means for positioning the intermediate product (12).

9. A method for molding a rubber intermediate product using a curing mold (34) according to any one of claims 5 to 8, comprising the steps of: positioning said intermediate product (12) on said support (16) such that said filamentary reinforcing elements (14) are substantially parallel to the longitudinal direction (22) of the blade in the closed position of the curing mould (3); placing the blade holder (20) in the closed position; A method comprising:

10. A method for molding a rubber intermediate product using a curing mold (34) according to any one of claims 5 to 8, comprising the steps of: positioning said intermediate product (12) on said support (16) such that said filamentary reinforcing elements (14) are substantially parallel to the longitudinal direction (22) of the blade in the closed position of the curing mould (3); placing the blade holder (20) in the closed position; Including, A method, wherein the intermediate product (12) is pre-cut prior to the step of positioning the intermediate product.

Images