Rubber Molding Method

Abstract

To provide a rubber molding method that can perform highly productive rubber molding while ensuring sufficient dimensional accuracy and adhesiveness even when molding rubber in a narrow space. [Solution] The method comprises an unevenness forming process (S1) for forming unevenness on the end surface of the metal part, an adhesive application process (S2) for applying adhesive to the end surface of the metal part, a molding die positioning process (S3) for positioning a molding die with a formed cavity facing the end surface of the metal part, a cross-linking molding process (S4) for extruding an uncross-linked rubber material toward the cavity while applying heat and pressure to cross-link it together with the adhesive within the cavity, a molding die removal process (S5) for removing the molding die, and a molding burr removal process (S6) for irradiating the metal part from the side of the end surface with a laser beam whose light direction is in the longitudinal direction of the metal part and scanning along the outer contour of the end surface to remove molding burrs that have seeped through gaps caused by the unevenness on the end surface and formed cross-links on the side of the metal part.

Description

[Technical Field]

[0001] The present invention relates to a rubber molding method for integrally molding rubber onto a metal part. [Background technology]

[0002] Among the components that make up industrial products, there are many that have rubber attached to metal parts to form a single integrated part. The attachment of rubber provides various benefits, such as improved durability due to the rubber's buffering effect against external shocks and friction, and improved stability due to the rubber's anti-slip effect against misalignment of the part, and these rubber-attached metal parts are now widely used.

[0003] One well-known method for attaching rubber to metal parts is to prepare a single piece of rubber with the desired shape in advance and then attach it to the desired location on the metal part with adhesive. This method simply involves attaching rubber with a predefined shape to the metal part, so as long as the dimensional accuracy of the single piece of rubber is ensured when it is prepared, the dimensional accuracy of the entire rubber-attached metal part is not likely to deteriorate during the rubber attachment process. Therefore, this method has the advantage of making it easy to ensure sufficient dimensional accuracy of the entire part, including the rubber.

[0004] On the other hand, this method is generally time-consuming because it requires separate production and attachment of the rubber. Therefore, this method is disadvantageous from the viewpoint of productivity when efficiently producing a large number of rubber-attached metal parts one after another. Furthermore, with this method, the adhesion between the rubber and the metal part depends solely on the adhesive placed at the interface between the two, so the expected adhesion is limited to the capabilities of the adhesive, making this method also disadvantageous from the viewpoint of ensuring sufficient adhesion between the rubber and the metal part.

[0005] Another known method for attaching rubber to metal parts is molding rubber on the metal part (see, for example, Patent Documents 1 and 2). Simply put, this method involves placing a molding die at the location on the metal part where the rubber is to be attached, pouring a fluid rubber material into the molding die, and allowing it to crosslink, thereby attaching rubber of the desired shape to the metal part. Compared to the above-mentioned method, in which the rubber is prepared and attached separately, this method is highly productive because the rubber is prepared and attached simultaneously. Furthermore, when used in conjunction with an adhesive, the rubber and adhesive can be crosslinked to each other on the metal part, making it easier to ensure sufficient adhesion compared to the above-mentioned method, which relies solely on the adhesive at the interface between the rubber and the metal part. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-182778 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-190237 Summary of the Invention [Problem to be solved by the invention]

[0007] However, as will be explained below, molding rubber onto metal parts does not always provide the advantages discussed above.

[0008] Generally, the method of molding rubber onto a metal part is often applied when attaching rubber to a relatively wide (extending) portion of the surface of a metal component. Specifically, examples include molding rubber onto one side of a flat metal component (see Patent Document 2) and molding rubber onto the side of a rod-shaped metal component (see Figure 4 of Patent Document 1). This is because the rubber material needs to be poured into a molding die so that the molding die surrounds the rubber molding portion of the metal component. Therefore, it is easier to position the molding die on a wide (extending) portion, and the adhesive surface area of ​​the rubber can be increased, resulting in improved adhesion. Conversely, the method of molding rubber onto a metal part may not achieve a high level of adhesion when attaching rubber to a relatively narrow, specific portion of the surface of a metal component, such as the end face of a long metal component.

[0009] Furthermore, when molding rubber onto a metal part, the rubber material is likely to protrude beyond the mounting position and crosslink, potentially reducing the dimensional accuracy of the entire part, including the rubber. For this reason, this method often requires a separate process to remove the crosslinked rubber material (so-called rubber burrs) that protrudes beyond the mounting position (e.g., by irradiating with a laser beam as described in Patent Documents 1 and 2). When rubber is molded onto a relatively wide (extending) area on the surface of a metal component, the rubber material only protrudes in the direction of the extension. Therefore, this removal process can be relatively easily performed by irradiating with a laser beam perpendicular to the protrusion direction, as described in Patent Documents 1 and 2. However, when molding rubber onto a relatively narrow, specific area, such as the end face of a long metal part, the direction of the protruding rubber material and the location of crosslinking are not so straightforward. Therefore, the removal process is time-consuming, which can reduce productivity, and insufficient removal can result in reduced dimensional accuracy.

[0010] Due to the problems described above, many skilled in the art believe that when molding rubber into a relatively narrow, specific location such as the end face of a long metal part, the above-mentioned method of separately preparing and attaching the rubber is more advantageous in terms of productivity and dimensional accuracy than the method of integrally molding the rubber onto the metal part, and that the adhesiveness is not significantly different. Thus, in the method of integrally molding rubber onto a metal part, further ingenuity is desired to ensure high productivity in the molding process while ensuring sufficient dimensional accuracy of the entire part, including the rubber, and sufficient adhesiveness between the rubber and the metal part.

[0011] In view of the above circumstances, the present invention aims to realize a rubber molding method that can mold rubber with high productivity while ensuring sufficient dimensional accuracy and sufficient adhesion, even when molding rubber into a relatively narrow specific location such as the end face of a long metal part. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the present invention provides the following rubber molding method.

[0013] [1] A rubber molding method for integrally molding rubber onto the end surface of a long metal part, a roughness forming step of forming roughness on the end surface of the metal component by blasting; an adhesive application step of applying an adhesive to the end surface of the metal component on which the concave-convex portions have been formed in the concave-convex portion forming step; a molding die positioning step of positioning a molding die having at least a flat plate shape in at least a portion thereof, with a cavity portion formed on one surface of the flat plate having a mold shape corresponding to the shape of the rubber to be molded, and with an introduction hole portion formed on the other surface opposite to the one surface of the flat plate through the inside of the flat plate and communicating with the cavity portion, with the cavity portion facing the end surface of the metal component to which the adhesive has been applied in the adhesive application step; a crosslinking molding step of introducing an uncrosslinked rubber material, which contains a crosslinking agent and undergoes a crosslinking reaction to become the rubber when subjected to heat and pressure, into the introduction hole, and extruding the material toward the cavity while applying heat and pressure to cause a crosslinking reaction, thereby crosslinking the uncrosslinked rubber material in the cavity together with the adhesive that has received heat conduction from the uncrosslinked rubber material in the cavity; a molding die removing step of separating excess rubber formed by crosslinking the uncrosslinked rubber material in the introduction hole from the rubber formed by crosslinking the uncrosslinked rubber material in the cavity, and removing the molding die from the metal part having the rubber adhered to its end surface; a molding burr removal process in which a laser beam, the beam direction of which is the longitudinal direction of the metal part, is irradiated from the end face of the metal part from which the molding die has been removed in the molding die removal process, and the laser beam is scanned along the outer contour of the end face, thereby removing molding burrs formed by crosslinking the uncrosslinked rubber material and the adhesive on the side face that have seeped out of the cavity through gaps caused by the unevenness on the end face when heat and pressure are applied to the uncrosslinked rubber material and spread onto the end face of the metal part and dripped down from the edge of the end face along the side face of the metal part in the longitudinal direction; A rubber molding method comprising the steps of:

[0014] [2] The metal part is a cylindrical metal part, the end surface is a ring-shaped end surface surrounded by an inner periphery and an outer periphery, and the rubber is molded into an endless band-shaped region extending along the ring shape on the end surface, The molding burr removal process removes the molding burrs on the side surfaces, which include peripheral molding burrs formed by the uncrosslinked rubber material and adhesive that have dripped from the outer peripheral edge of the ring-shaped end face along the outer peripheral surface of the cylindrical metal part and crosslinking on the outer peripheral surface, and inner molding burrs formed by the uncrosslinked rubber material and adhesive that have dripped from the inner peripheral edge of the ring-shaped end face along the inner peripheral surface of the cylindrical metal part and crosslinking on the inner peripheral surface, by scanning the laser beam along the outer and inner peripheral surfaces of the ring-shaped end face. This is a rubber molding method described in [1].

[0015] [3] The metal part is a substantially cylindrical metal part, the end surface is an annular end surface surrounded by the circular inner circumference and the circular outer circumference as the ring shape, and the rubber is molded into an annular region as the band-like region extending along the annular shape, The molding burr removing step includes: an outer periphery scanning step of limiting a scanning area to an annular band area sandwiched between the circumference of an outer periphery scanning reference circle having a diameter larger than the diameter of the outer periphery of the annular area by a predetermined length and the outer periphery of the circular end face, and performing scanning with the laser beam; and an inner side scanning process for limiting the scanning area to an annular band area sandwiched between the circumference of an inner side scanning reference circle having a diameter smaller by a predetermined length than the diameter of the inner circumference of the annular area and the inner circumference of the circular end face, and performing scanning with the laser beam.

[0016] [4] The rubber molding method according to [3], wherein the metal part is a substantially cylindrical metal part having a total length in the longitudinal direction of 10 to 30 mm and a maximum diameter in a direction perpendicular to the longitudinal direction of 5 to 15 mm.

[0017] [5] The rubber molding method according to [4], wherein the unevenness forming step is performed by blasting to form minute unevenness with a height difference of 0.01 to 1.00 mm on the end surface.

[0018] [6] The molding die is a split type molding die, and the molding die comprises: a first split mold that surrounds the metal component except for the end surface and holds the metal component in an upright position with the end surface facing vertically upward; a flat-plate-shaped second split mold that is stacked on the first split mold from the side of the end face of the metal component held in an upright state by the first split mold, and that has the one surface that abuts the end face and the other surface opposite to the one surface, the second split mold having the cavity portion on the one surface and having, as the introduction hole portion, a concave introduction recess formed on the other surface into which the uncrosslinked rubber material is introduced, and a gate portion that extends tapered from a bottom surface of the concave introduction recess toward the cavity portion and serves as a flow path for introducing the uncrosslinked rubber material introduced into the introduction recess into the cavity portion; and a third split mold that is laminated on the other surface of the second split mold, and has a convex heating and pressing portion formed on the surface facing the other surface that fits into the concave introduction recess, and the third split mold that has been heated by the supply of heat and has its temperature increased by pressing the heating and pressing portion against the uncrosslinked rubber material introduced into the introduction recess while fitting it into the introduction recess, thereby applying heat and pressure to the uncrosslinked rubber material and extruding it towards the cavity portion through the gate portion. [2] The rubber molding method according to any one of [2] to [5], [Effects of the Invention]

[0019] Generally, when rubber is molded onto a metal part, it is difficult to achieve high adhesion when the rubber is attached to a relatively narrow, specific location on the surface of a metal component, such as the end face of a long metal part, because the adhesive area for the rubber cannot be made large. In contrast, the rubber molding method of the present invention creates irregularities on the end face of the metal part to substantially increase the adhesive area, and then heats and pressurizes both the uncrosslinked rubber material and the adhesive to crosslink them, thereby enhancing the adhesive strength and molding the rubber. As a result, the present invention ensures sufficient adhesion between the rubber and the metal part, even when the rubber is attached to a relatively narrow, specific location, such as the end face of a long metal part.

[0020] On the other hand, in the present invention, pressure is applied to the uncrosslinked rubber material and adhesive in the cavity that is placed on the uneven end face so as to press them against the end face, which makes it easy for the uncrosslinked rubber material and adhesive to seep out of the cavity through gaps caused by the unevenness. The seeped uncrosslinked rubber material and adhesive spread over the end face of the metal part, and some of it may reach the edge of the end face and drip from the edge of the end face along the side face of the metal part in the longitudinal direction (the direction in which the metal part extends longitudinally), and may end up crosslinking on the side face (hereinafter referred to as molding burrs).

[0021] Generally, when rubber is molded onto the end faces of metal parts, the purpose is usually to improve durability by cushioning the end face against external impacts and friction, and to improve stability by preventing slippage against misalignment. Therefore, uncrosslinked rubber material and adhesive on the end face that seeps out of the cavity but does not reach the edge of the end face and remains crosslinked around the rubber may cause cosmetic problems but do not impair the functionality of the rubber and do not pose any particular problems. However, molding burrs can change the effective diameter of the end of the part, reducing the dimensional accuracy of the part and potentially interfering with the intended functionality of the metal part.

[0022] Therefore, in the present invention, molding burrs are removed by irradiating the metal part from the end face side with a laser beam whose light direction is in the longitudinal direction of the metal part and scanning along the outer contour of the end face.

[0023] Because the thickness of the molding burrs protruding from the side surfaces is not particularly large, high precision is required for both the irradiation and scanning of the laser beam to sufficiently remove the molding burrs on the side surfaces 24 by scanning a laser beam with the beam direction in the longitudinal direction of the metal part. While such high-precision irradiation and scanning is difficult with other irradiation-type burr removal methods other than laser beams, such as water jets, laser beams generally have significantly higher directionality than water jets and the like, making such high-precision irradiation and scanning possible. For example, a laser marker device can print on the irradiated object with high-precision irradiation and scanning. Therefore, using the laser beam from such a laser marker device as the above-mentioned laser beam used to remove molding burrs enables high-precision irradiation and scanning.

[0024] In this way, the present invention uses a laser beam oriented in the longitudinal direction of the metal part to scan along the outer contour of the end face of the metal part, making it possible to sufficiently remove only the molding burrs without accidentally irradiating the molded rubber with the laser beam. As a result, the present invention ensures sufficient dimensional accuracy for the entire part, including the rubber.

[0025] Furthermore, in the present invention, burrs can be removed by simply scanning the laser beam along the outer edge of the end face immediately after molding. This eliminates the need to remove the rubber-molded metal part 1 from the production line and manually remove the burrs using physical tools such as a paper knife or file.

[0026] Furthermore, if the laser beam removal methods described in Patent Documents 1 and 2 were to be applied, the laser beam would be irradiated in a direction perpendicular to the direction in which the molding burrs extend, i.e., toward the side of the metal part (see, for example, Figure 4 of Patent Document 1). In this case, it would be necessary to either rotate the laser irradiation device around the metal part while irradiating the laser beam from the laser irradiation device with the side of the metal part facing the laser irradiation device, or rotate the metal part with its longitudinal direction as the rotation axis. In either case, the work of removing molding burrs from each metal part would be large-scale, and it would not be suitable for removing molding burrs from multiple metal parts one after another.

[0027] In contrast, the method of the present invention, in which a laser beam oriented in the longitudinal direction of a metal part is scanned along the outer contour of the end face of the metal part, makes it possible to easily remove molding burrs from the side of the metal part using a general-purpose laser irradiation device (such as the laser marker device described above) that can scan a laser beam in the so-called XY plane, making it suitable for removing molding burrs from multiple metal parts one after another.

[0028] In this way, the method of the present invention, in which a laser beam with its light direction aligned with the longitudinal direction of the metal part is scanned along the outer contour of the end face of the metal part, can quickly complete the removal of molding burrs, thereby making full use of the advantage of one-piece rubber molding, which is high productivity, and ensuring high productivity in the molding process.

[0029] As a result, the present invention realizes a rubber molding method that can mold rubber with high productivity while ensuring sufficient dimensional accuracy and sufficient adhesion, even when molding rubber into a relatively narrow specific location such as the end face of a long metal part. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a flowchart showing a rubber molding method according to one embodiment of the present invention. [Figure 2]2 is a schematic cross-sectional view of an integrally molded rubber part produced by integrally molding rubber with a metal part using the rubber molding method shown in the flowchart of FIG. 1. FIG. [Figure 3] 10A to 10C are diagrams illustrating a concavo-convex forming step. [Figure 4] 10A to 10C are diagrams illustrating a process of applying an adhesive. [Figure 5] FIG. 10 is a diagram schematically illustrating a molding die arrangement step. [Figure 6] FIG. 2 is a diagram schematically illustrating a cross-linking molding step. [Figure 7] FIG. 10 is a diagram showing the metal part and the rubber after the molding die removal step has been performed. [Figure 8] 8 is a diagram showing the metal part and the rubber after the molding die removal step of FIG. 7 has been performed, as viewed from the end face side. [Figure 9] FIG. 10 is a diagram schematically illustrating a molding burr removal step. [Figure 10] 10A and 10B are diagrams illustrating the metal part and the rubber after the outer circumferential side scanning step and the inner circumferential side scanning step have been performed. [Figure 11] 10 is a diagram showing the metal part and the rubber from the end face side after the outer circumferential side scanning step and the inner circumferential side scanning step have been performed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes and improvements may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0032] FIG. 1 is a flowchart showing a rubber molding method according to one embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of an integrally molded rubber part 3 produced by integrally molding rubber 2 with a metal part 1 using the rubber molding method shown in the flowchart of FIG.

[0033] The rubber molding method of this embodiment is a rubber molding method for integrally molding rubber 2 onto an end surface 4 of a long metal part 1, the cross section of which is shown in Fig. 2. By attaching rubber 2 to the end surface 4 of the metal part 1, the rubber molding method of this embodiment aims to improve the durability of the metal part 1 by providing a cushioning effect of the rubber against external impacts and friction, and to improve stability by providing an anti-slip effect of the rubber against misalignment of the metal part 1.

[0034] An example of such a metal part 1 is a cylindrical metal part having an annular end surface 4 surrounded by an inner periphery and an outer periphery. The rubber 2 in this case can be molded into an endless strip-like region on the end surface 4 that extends along the annular shape. A typical example of the metal part 1 is a substantially cylindrical metal part having an annular end surface 4 surrounded by a circular inner periphery and a circular outer periphery. The rubber 2 in this case can be molded into an annular region that extends along the annular shape. More specifically, an example of such a metal part 1 is the above-mentioned substantially cylindrical metal part having a total length of 10 to 30 mm in the longitudinal direction and a maximum diameter of 5 to 15 mm in the direction perpendicular to the longitudinal direction. An example of an integrally molded rubber part 3 produced by integrally molding the rubber 2 with such a metal part 1 is an injector valve part used in an automobile engine, for example.

[0035] The steps of the rubber molding method of this embodiment are described below. In the rubber molding method of this embodiment, the unevenness forming step, adhesive application step, molding die placement step, crosslinking step, molding die removal step, and molding burr removal step are performed in this order. Each of these steps will be described in detail below in the molding process until one rubber 2 is integrally molded onto one metal part 1. However, this is merely an example for the purpose of explanation, and in reality, each step is performed one after another on multiple metal parts 1 arranged in an upright state in a plane perpendicular to the longitudinal direction of the metal parts 1, while maintaining that upright state. By performing processing while maintaining the upright state in this way, the effort of changing the position of the metal parts 1 is eliminated, improving productivity.

[0036] In the rubber molding method of this embodiment, first, a roughness forming step is carried out, in which roughness is formed on the end surface 4 of the metal part 1 by blasting (step S1 in FIG. 1).

[0037] FIG. 3 is a diagram showing a schematic diagram of the unevenness forming step.

[0038] Figure 3 shows an example of the processing performed on the right-hand end face 4 of the end faces 4 of the metal part 1, which are shown separated into left and right in the cross-sectional view of Figure 2. The following process diagrams will also use the right-hand end face 4 as an example for explanation, but similar processes are performed on the entire annular end face 4, including the left-hand end face 4 in Figure 2.

[0039] In the asperity forming step, as shown in Fig. 3, a blasting process is performed on the end surface 4 of the metal part 1 by colliding abrasive particles 6 at high speed using a polishing device 5. The collision of the abrasive particles 6 at this time forms random asperities on the end surface 4 of the metal part 1. For example, minute asperities with a height difference of 0.01 to 1.00 mm are formed on the end surface 4 by the above-mentioned blasting process.

[0040] An adhesive application step is performed after the unevenness formation step of step S1 in Fig. 1. In the adhesive application step, adhesive 7 is applied to the end surface 4 of the metal part 1 on which the unevenness has been formed in the unevenness formation step (step S2 in Fig. 1). Here, adhesive 7 is a type of vulcanizing adhesive that undergoes a cross-linking reaction when subjected to heat and pressure, thereby cross-linking and exerting an adhesive effect.

[0041] FIG. 4 is a diagram showing a schematic diagram of the adhesive application step.

[0042] In the adhesive application step, as shown in Fig. 4, an application device 8 sprays adhesive 7 onto the end face 4 of the metal part 1 on which the irregularities have been formed in the irregularity formation step of step S1 in Fig. 1, thereby applying the adhesive 7 to the end face 4. The sprayed adhesive 7 is not cross-linked and therefore has some fluidity, so the applied adhesive 7 spreads over the end face 4 while penetrating between the irregularities of the end face 4.

[0043] A molding die arrangement step is performed after the adhesive application step of step S2 in Fig. 1. In the molding die arrangement step, a molding die is arranged for the metal part 1 to which adhesive 7 has been applied in the adhesive application step of step S2 in Fig. 1 (step S3 in Fig. 1).

[0044] FIG. 5 is a diagram schematically illustrating the molding die arrangement step.

[0045] As shown in Fig. 5, molding die 10 placed in the molding die placement step has at least a portion (second split die 12 described below) that has a flat plate shape, and one surface 12a of the flat plate has a cavity portion 9 formed therein that has a mold shape corresponding to the shape of rubber 2 (see Fig. 2) to be molded. Furthermore, molding die 10 has an introduction hole portion 16 formed on the other surface 12b opposite to one surface 12a of the flat plate, which passes through the inside of the flat plate and communicates with cavity portion 9. Molding die 10 is placed with cavity portion 9 facing end surface 4 of metal component 1 to which adhesive was applied in the adhesive application step of step S2 in Fig. 1.

[0046] Following the molding die placement step of step S3 in FIG. 1, a crosslinking molding step is performed. In the crosslinking molding step, crosslinking of the uncrosslinked rubber material and adhesive is performed in the cavity portion 9 of the molding die 10 placed in the molding die placement step (step S4 in FIG. 1). In this crosslinking molding step, first, an uncrosslinked rubber material 17 is introduced into the introduction hole portion 16 in FIG. 5 (specifically, the introduction recess 14 (described later) above the introduction hole portion 16). The uncrosslinked rubber material 17 is a rubber material that contains a crosslinking agent and undergoes a crosslinking reaction when subjected to heat and pressure, becoming rubber 2 in FIG. 2. In the crosslinking molding step, the uncrosslinked rubber material 17 introduced into the introduction hole portion 16 is extruded toward the cavity portion 9 while applying heat and pressure, as shown by the white arrow in FIG. 5.

[0047] FIG. 6 is a diagram showing a cross-linking molding step.

[0048] The uncrosslinked rubber material 17 extruded from the introduction hole 16 toward the cavity 9 while being subjected to heat and pressure undergoes a crosslinking reaction, and as shown in Fig. 6, crosslinking occurs inside the introduction hole 16 (specifically, the gate 15 (described later) below the introduction hole 16) and the cavity 9. At this time, the adhesive 7, which has received heat from the uncrosslinked rubber material 17 that has entered the cavity 9, is also crosslinked inside the cavity 9 together with the uncrosslinked rubber material 17.

[0049] Here, the molding die 10 used in the molding die placement step of step S3 and the cross-linking molding step of step S4 in FIG. 1 will be described in more detail with reference to FIGS.

[0050] In the molding die arrangement step and the cross-linking molding step of this embodiment, as shown in Figures 5 and 6, it is preferable that molding die 10 is a split-type molding die comprising a first split die 11, a second split die 12, and a third split die 13. These three dies that make up molding die 10 will be described below.

[0051] The first split mold 11 is a mold that surrounds the metal part 1 except for the end face 4 of the metal part 1 and holds the metal part 1 in an upright position with the end face 4 facing vertically upward (upward in Figures 5 and 6).

[0052] The second split mold 12 is a flat mold that is stacked on the first split mold 11 from the side of the end face 4 of the metal component 1 that is held upright by the first split mold 11, and has the above-mentioned one surface 12a that abuts the end face 4 and the other surface 12b opposite to the one surface 12a. The second split mold 12 has the above-mentioned cavity portion 9 on this one surface 12a. The second split mold 12 also has an introduction recess 14 and a gate portion 15 as the above-mentioned introduction hole portion 16. The introduction recess 14 is a recessed portion formed on the other surface 12b into which the uncrosslinked rubber material 17 is introduced. The gate portion 15 is a portion that extends tapered from the bottom surface of the recessed introduction recess 14 toward the cavity portion 9, and serves as a flow path for the uncrosslinked rubber material 17 introduced into the introduction recess 14 to be introduced into the cavity portion 9.

[0053] The third split mold 13 is a mold that is stacked on the other surface 12b of the second split mold 12. A convex heating and pressing portion 29 that fits into the concave introduction recess 14 is formed on the surface 13a of the third split mold 13 facing the other surface 12b, and the heating and pressing portion 29 can be supplied with heat by a mechanism (not shown). In the crosslinking molding process of step S4 in FIG. 1, the third split mold 13 presses the heating and pressing portion 29, whose temperature has increased due to the supply of heat, against the uncrosslinked rubber material 17 introduced into the introduction recess 14, and fits it into the introduction recess 14 (see the outline arrow in FIG. 5). As a result, the uncrosslinked rubber material 17 is extruded toward the cavity 9 through the gate 15 while being subjected to heat and pressure.

[0054] The above is a description of the split-type molding die 10. By using such a split-type molding die 10 in the molding die arrangement step of step S3 and the cross-linking molding step of step S4 in Fig. 1, the work of molding the rubber 2 onto the end surface 4 of the metal part 1 can be carried out efficiently. Below, we will explain the steps that are carried out after the cross-linking molding step of step S4.

[0055] A molding die removal step is performed after the crosslinking molding step of step S4 in Fig. 1. In the molding die removal step, excess rubber formed by crosslinking of the uncrosslinked rubber material 17 that has entered the introduction hole 16 (specifically, the gate 15 below the introduction hole 16) is separated from the rubber 2 in Fig. 2 that has been crosslinked from the uncrosslinked rubber material 17 that has entered the cavity 9. Then, the molding die 10 is removed from the metal part 1 with the rubber 2 adhered to the end surface 4 (step S5 in Fig. 1).

[0056] Generally, when molding rubber onto a metal part, when attaching rubber to a relatively narrow, specific location on the surface of the metal member, such as the end face 4 of the long metal part 1 described above, the adhesive area of ​​the rubber cannot be made large, so it is often not possible to expect very high adhesion.

[0057] In contrast, in the rubber molding method of this embodiment, unevenness is formed on the end surface 4 of the metal part 1 to substantially increase the adhesion area, and then the uncrosslinked rubber material 17 and the adhesive 7 are both heated and pressurized to crosslink them together, thereby increasing the adhesive strength and molding the rubber. As a result, the rubber molding method of this embodiment can ensure sufficient adhesion between the rubber 2 and the metal part 1 even when attaching the rubber 2 to a relatively narrow specific location such as the end surface 4 of a long metal part 1.

[0058] FIG. 7 is a diagram showing the metal part 1 and the rubber 2 after the molding die removal process has been performed, and FIG. 8 is a diagram showing the metal part 1 and the rubber 2 after the molding die removal process of FIG. 7 has been performed, viewed from the end face 4 side.

[0059] As described above, in this embodiment, in the crosslinking molding process of step S4 in FIG. 1 (see FIG. 6), pressure is applied to the uncrosslinked rubber material 17 and adhesive 7 in the cavity 9 arranged on the uneven end surface 4 so as to press them against the end surface 4. This causes the uncrosslinked rubber material 17 and adhesive 7 to easily seep out of the cavity through gaps caused by the unevenness. The seeped uncrosslinked rubber material 17 and adhesive 7 spread over the end surface 4 of the metal part 1, and some of them reach the edge of the end surface 4 and drip from the edge along the side surface 24 of the metal part 1 in the longitudinal direction of the metal part 1 (the vertical direction in FIG. 7), thereby crosslinking on the side surface 24. In FIG. 7, the uncrosslinked rubber material 17 and adhesive 7 crosslinked on the side surface 24 of the metal part 1 in this way are shown as molding burrs 20.

[0060] The presence of molding burrs 20 on the side surface 24 reduces the dimensional accuracy of the inner diameter W1 and outer diameter W2 of the tip of the metal part 1 shown in FIG. 2. Specifically, among the molding burrs 20 on the side surface 24 of FIG. 7, the presence of peripheral molding burr 19 on the outer side surface 24 (outer surface 22) of FIG. 7 and FIG. 8 partially increases the effective size of the outer diameter W2 of the tip of the metal part 1 shown in FIG. 2. Furthermore, among the molding burrs 20 on the side surface 24 of FIG. 7, the presence of inner molding burr 18 on the inner side surface 24 (inner surface 23) of FIG. 7 and FIG. 8 partially reduces the effective size of the inner diameter W1 of the tip of the metal part 1 shown in FIG. 2. In this way, the presence of molding burrs 20 (inner molding burr 18 and outer molding burr 19) acts to prevent the metal part 1 from achieving the originally intended dimensions.

[0061] In addition to molding burrs 20 (inner peripheral molding burrs 18 and outer peripheral molding burrs 19), there are also uncrosslinked rubber material 17 and adhesive 7 (hereinafter referred to as end face molding burrs 21) that seeped out of cavity portion 9 but did not reach the edge of end face 4 and instead crosslinked directly on end face 4 of metal part 1. However, unlike inner peripheral molding burrs 18 and outer peripheral molding burrs 19, end face molding burrs 21 do not affect the effective length of the dimensions of metal part 1, nor do they affect the functionality of metal part 1 or rubber 2. For this reason, the presence of end face molding burrs 21 does not actually pose a major problem, apart from appearance issues.

[0062] Therefore, in the rubber molding method of this embodiment, a molding burr removal process is performed after the molding mold removal process of step S5 in Figure 1 (step S6 in Figure 1) in order to remove molding burrs 20 (inner peripheral molding burrs 18 and outer peripheral molding burrs 19) on the side surfaces, which are particularly harmful in that they reduce dimensional accuracy.

[0063] FIG. 9 is a diagram schematically illustrating the molding burr removing step.

[0064] In the molding burr removal process, a laser irradiation device 25 irradiates the metal part 1 with the rubber 2, from which the molding die 10 (see FIG. 6) has been removed in the molding die removal process of step S5 in FIG. 1, with a laser beam 26 whose light direction is in the longitudinal direction of the metal part 1 (the up-and-down direction in FIG. 9), from the side of the end face 4 of the metal part 1. Such scanning with the laser beam 26 is performed along the outline of the end face 4 of the metal part 1, and this scanning removes the molding burr 20 on the side face 24 of the metal part 1 described above in FIG. 7.

[0065] To explain this scanning more specifically using Figure 8, which shows the metal part 1 with rubber 2 from the side of the end face 4, in the molding burr removal process, a laser beam 26 is scanned along the outer periphery (outer periphery 22) and inner periphery (inner periphery 23) of the annular end face 4. By such scanning, the outer periphery molding burrs 19 and inner periphery molding burrs 18 protruding from the outer periphery 22 and inner periphery 23, respectively, are irradiated with the laser beam 26 in Figure 9 and removed from the outer periphery 22 and inner periphery 23.

[0066] Because the thickness of the molding burrs 20 protruding from the side surfaces 24 is not particularly large, scanning the laser beam 26 in the longitudinal direction of the metal part 1 (the vertical direction in Figure 9) requires high precision in both the irradiation and scanning of the laser beam 26 to adequately remove the molding burrs 20 on the side surfaces 24. While such high-precision irradiation and scanning is difficult with other irradiation-type burr removal methods such as water jets, laser beams generally have significantly higher directivity than water jets, making such high-precision irradiation and scanning possible. For example, a laser marker device can print on the irradiated object with high-precision irradiation and scanning. Therefore, using a laser beam from such a laser marker device as the laser beam 26 of the laser irradiation device 25 described above used to remove molding burrs 20 enables high-precision irradiation and scanning. An example of a laser marker device that can be used as the laser irradiation device 25 is the MX-Z2000H-V1 laser marker device manufactured by Omron Corporation.

[0067] In this manner, in this embodiment, by scanning along the outer contour of the end face 4 of the metal part 1 using the laser beam 26 whose light direction is the longitudinal direction of the metal part 1, it is possible to sufficiently remove only the molding burrs 20 without accidentally irradiating the molded rubber 2 with the laser beam 26. As a result, in this embodiment, sufficient dimensional accuracy of the entire part, including the rubber 2, can be ensured.

[0068] Furthermore, in this embodiment, removal of molding burrs 20 is completed by simply scanning laser beam 26 along the outer contour of end face 4 immediately after molding. Therefore, there is no need to remove metal part 1 after rubber 2 molding from the production line and manually remove molding burrs using physical tools such as a paper knife or file.

[0069] Furthermore, if the laser beam removal methods described in Patent Documents 1 and 2 were to be applied, the laser beam would be irradiated in a direction perpendicular to the direction in which the molding burr 20 extends, i.e., toward the side surface 24 of the metal part 1 (see, for example, Figure 4 of Patent Document 1). In this case, it would be necessary to either rotate the laser beam 26 irradiating device 25 around the metal part 1 while irradiating the laser beam 26 from the laser beam irradiating device 25 with the side surface 24 of the metal part 1 facing the laser beam 26, or rotate the metal part 1 around its longitudinal axis. In either case, the work of removing the molding burrs from each metal part 1 would be large-scale, making it unsuitable for removing the molding burrs 20 from multiple metal parts 1 one after another. Furthermore, the molding burrs 20 that can be removed using this method are only the peripheral molding burrs 19 on the outer surface 22 of the side surface 24 of the metal part 1; the inner molding burrs 18 on the inner surface 23 cannot be removed using this method.

[0070] In contrast, with the method of scanning a laser beam 26, whose light direction is the longitudinal direction of the metal part, along the outer contour of the end face 4 of the metal part 1, as in this embodiment, the molding burrs 20 on the side face 24 of the metal part 1 can be easily removed using a general-purpose laser irradiation device (such as the laser marker device described above) that is capable of scanning a laser beam in the so-called XY plane. This is therefore suitable for performing molding burr removal work on multiple metal parts 1 one after another. Furthermore, with the method of this embodiment, it is possible to remove not only the peripheral molding burrs 19 on the outer surface 22 of the side face 24 of the metal part 1, but also the inner molding burrs 18 on the inner surface 23 in a similar manner.

[0071] As described above, the method of this embodiment in which the laser beam 26, whose light direction is the longitudinal direction of the metal part 1, is scanned along the outer contour of the end face 4 of the metal part 1, can quickly complete the removal of molding burrs 20. This makes it possible to fully utilize the advantage of integral molding of rubber, which is high productivity, and ensures high productivity in the molding process.

[0072] As a result, in this embodiment, a rubber molding method is realized that can mold rubber 2 in a relatively narrow specific location such as the end face 4 of a long metal part 1 while ensuring sufficient dimensional accuracy and sufficient adhesion, thereby enabling highly productive rubber molding.

[0073] The molding burr removing step in this embodiment will be described in more detail below.

[0074] In the molding burr removal process of this embodiment, in order to more reliably and thoroughly remove molding burrs 20, it is preferable to perform the above-mentioned scanning of the laser beam 26 along the outer contour of the end face 4 of the metal part 1 through an outer circumferential scanning process and an inner circumferential scanning process described below.

[0075] As described above, the metal part 1 is typically a substantially cylindrical metal part, the end face 4 being an annular end face surrounded by a circular inner periphery (inner circumferential surface 23) and a circular outer periphery (outer circumferential surface 22), and the rubber 2 is molded into an annular region extending along the annular shape (see FIG. 8). Below, the outer periphery side scanning process and inner periphery side scanning process performed on such a metal part 1 and rubber 2 will be described with reference to FIG. 8.

[0076] In the outer periphery side scanning process, scanning is performed with the laser beam 26 on an annular band-like area sandwiched between the circumference of an outer periphery side scanning reference circle 28, which has a diameter larger than the diameter of the outer periphery of the annular area (the area of ​​rubber 2 in FIG. 8) by a predetermined length d2, and the circular outer periphery (outer periphery surface 22) of the end face 4. At this time, scanning is not performed on the annular band-like area sandwiched between the outer periphery of the annular area (the area of ​​rubber 2 in FIG. 8) and the circumference of the outer periphery side scanning reference circle 28.

[0077] In this way, by limiting the scanning area to the area from the outer periphery scanning reference circle 28, which is a predetermined length d2 away from the rubber 2, to the circular periphery (outer periphery 22) of the end face 4, it is possible to more reliably remove the outer periphery molding burr 19 while preventing the laser beam 26 from being irradiated by mistake onto the rubber 2, even if there is some spread in the directionality of the laser beam 26.

[0078] On the other hand, in the inner circumference side scanning process, scanning is performed with the laser beam 26 on an annular band-like area sandwiched between the circumference of an inner circumference side scanning reference circle 27, which has a diameter smaller than the diameter of the inner circumference of the annular area (the area of ​​rubber 2 in FIG. 8) by a predetermined length d1, and the above-mentioned circular inner circumference (inner peripheral surface 23) of the end face 4. At this time, scanning is not performed on the annular band-like area sandwiched between the inner circumference of the annular area (the area of ​​rubber 2 in FIG. 8) and the circumference of the inner circumference side scanning reference circle 27.

[0079] In this way, by limiting the scanning area to the area from the inner scanning reference circle 27, which is a predetermined length d1 away from the rubber 2, to the circular inner circumference (inner surface 23) of the end face 4, even if there is some spread in the directionality of the laser beam 26, it is possible to prevent the laser beam 26 from being irradiated accidentally onto the rubber 2, and to more reliably remove the inner molding burrs 18.

[0080] There are no particular limitations on the manner in which the two annular band-shaped regions on both sides of the rubber 2 are scanned. The circumferential scanning may be performed while gradually increasing the diameter of the circumference, or the circumferential scanning may be performed while gradually decreasing the diameter of the circumference. For example, in the outer circumferential scanning process, the circumferential scanning may be performed while gradually increasing the diameter of the circumference from the outer circumferential scanning reference circle 28 to the circular outer periphery (outer circumferential surface 22) of the end face 4, and in the inner circumferential scanning process, the circumferential scanning may be performed while gradually decreasing the diameter of the circumference from the inner circumferential scanning reference circle 27 to the circular inner periphery (inner circumferential surface 23) of the end face 4. In this case, fragments of the outer circumferential molding burr 19 and the inner circumferential molding burr 18 removed by the laser beam 26 tend to scatter in a direction away from the rubber 2, which prevents the fragments from adhering to the rubber 2.

[0081] FIG. 10 is a diagram showing the metal part 1 and the rubber 2 after the outer circumferential side scanning process and the inner circumferential side scanning process have been performed, and FIG. 11 is a diagram showing the metal part 1 and the rubber 2 after the outer circumferential side scanning process and the inner circumferential side scanning process have been performed, from the side of the end face 4.

[0082] In the metal part 1 and rubber 2 after the outer peripheral scanning process and the inner peripheral scanning process, some end face molding burrs 21 remain on the inner peripheral side (see Figure 10) and outer peripheral side (see Figures 10 and 11) of the rubber 2 on the end face 4 of the metal part 1, but all of the inner peripheral molding burrs 18 and outer peripheral molding burrs 19 have been removed. As described above, unlike the inner peripheral molding burrs 18 and the outer peripheral molding burrs 19, the end face molding burrs 21 do not affect the effective length of the dimensions of the metal part 1, nor do they affect the functions of the metal part 1 or the rubber 2. Therefore, sufficient dimensional accuracy is ensured in a more reliable manner in the metal part 1 and rubber 2 after the outer peripheral scanning process and the inner peripheral scanning process have been performed.

[0083] As described above, in order to more reliably and thoroughly remove molding burrs 20, it is preferable to perform scanning of laser beam 26 along the outer periphery of end face 4 of metal part 1 through an outer periphery scanning process and an inner periphery scanning process, but there may be cases where minimizing the number of work processes is the top priority. In such cases, the present invention may omit circumferential scanning performed while changing the circumferential diameter, and perform only circumferential scanning along the circular outer periphery (outer periphery surface 22) and inner periphery (inner periphery surface 23) of end face 4.

[0084] This concludes the description of this embodiment.

[0085] The above description has mainly focused on an example in which the metal part 1 is a substantially cylindrical metal part with the rubber 2 molded onto its annular end surface 4 (see FIGS. 8 and 11). However, the present invention also applies to a case in which the metal part 1 is not substantially cylindrical, but is a tubular metal part with an elliptical or polygonal cross section, with the rubber molded onto the elliptical or polygonal annular end surface. [Industrial Applicability]

[0086] The present invention is useful for realizing a rubber molding method that can mold rubber with high productivity while ensuring sufficient dimensional accuracy and sufficient adhesion, even when molding rubber into a relatively narrow specific location such as the end face of a long metal part. [Explanation of symbols]

[0087] 1: Metal parts, 2: Rubber, 3: Rubber integrally molded parts, 4: End face, 5: Polishing equipment, 6: Abrasive particles, 7: adhesive, 8: Coating device, 9: Cavity part, 10: Molding mold, 11: 1st division type, 12:Second split type, 12a: One side, 12b: The other side, 13: Third division type, 13a: Face 14: introduction recess, 15: Gate section, 16:Introduction hole, 17: Uncrosslinked rubber material, 18: Inner molding burr, 19: Periphery molding burr, 20: Molding burrs, 21: End face molding burr, 22: Outer surface, 23: Inner peripheral surface, 24: Side, 25: Laser irradiation device, 26: Laser beam, 27: Inner scanning reference circle, 28: Outer scanning reference circle, 29: Heat pressing unit, W1: inner diameter, W2: outer diameter, d1, d2: Predetermined lengths.

Claims

1. A rubber molding method for integrally molding rubber onto an end surface of a long metal part, comprising: a roughness forming step of forming roughness on the end surface of the metal component by blasting; an adhesive application step of applying an adhesive to the end surface of the metal component on which the concave-convex portions have been formed in the concave-convex portion forming step; a molding die positioning step of positioning a molding die having at least a flat plate shape in at least a portion thereof, with a cavity portion formed on one surface of the flat plate having a mold shape corresponding to the shape of the rubber to be molded, and with an introduction hole portion formed on the other surface opposite to the one surface of the flat plate through the inside of the flat plate and communicating with the cavity portion, with the cavity portion facing the end surface of the metal component to which the adhesive has been applied in the adhesive application step; a crosslinking molding step of introducing an uncrosslinked rubber material, which contains a crosslinking agent and undergoes a crosslinking reaction to become the rubber when subjected to heat and pressure, into the introduction hole, and extruding the material toward the cavity while applying heat and pressure, thereby causing a crosslinking reaction within the cavity together with the adhesive that has received heat conduction from the uncrosslinked rubber material to crosslink; a molding die removing step of removing the molding die from the metal part having the rubber formed by crosslinking the uncrosslinked rubber material in the cavity portion and adhering to the end surface thereof; a molding burr removal step in which a laser beam having a beam direction in the longitudinal direction of the metal part is irradiated from the end face of the metal part, from which the molding die has been removed in the molding die removal step, and the laser beam is scanned along the outer contour of the end face, thereby removing molding burrs formed by crosslinking the uncrosslinked rubber material and the adhesive on the side face that have seeped out of the cavity through gaps caused by the unevenness on the end face when heat and pressure are applied to the uncrosslinked rubber material and spread onto the end face of the metal part and dripped down from the edge of the end face along the side face of the metal part in the longitudinal direction, The molding die is a split type molding die, and the molding die comprises: a first split mold that surrounds the metal component except for the end surface and holds the metal component in an upright position with the end surface facing vertically upward; a second split mold in the shape of a flat plate, which is stacked on the first split mold from the side of the end face of the metal component held in an upright state by the first split mold and has the one surface abutting the end face and the other surface opposite to the one surface, the second split mold having the cavity portion on the one surface and having, as the introduction hole portion, a concave introduction recess formed on the other surface into which the uncrosslinked rubber material is introduced, and a gate portion extending tapered from a bottom surface of the concave introduction recess toward the cavity portion and serving as a flow path for introducing the uncrosslinked rubber material introduced into the introduction recess into the cavity portion; a third split mold that is laminated on the other surface of the second split mold, and on the surface facing the other surface, a convex heating and pressing portion that fits into the concave introduction recess is formed, and the third split mold that has been heated by the supply of heat and has its temperature increased is pressed against the uncrosslinked rubber material introduced into the introduction recess while fitting into the introduction recess, thereby applying heat and pressure to the uncrosslinked rubber material and extruding it towards the cavity portion through the gate portion.

2. the metal part is a cylindrical metal part, the end surface is an annular end surface surrounded by an inner periphery and an outer periphery, and the rubber is molded into an endless band-like region extending along the annular shape on the end surface, The molding burr removal process removes the molding burrs on the side surfaces by scanning the laser beam along the outer and inner circumferences of the annular end face, the molding burrs being outer peripheral molding burrs formed by the uncrosslinked rubber material and the adhesive dripping from the outer peripheral edge of the annular end face along the outer peripheral surface of the cylindrical metal part and crosslinking on the outer peripheral surface, and the inner peripheral molding burrs formed by the uncrosslinked rubber material and the adhesive dripping from the inner peripheral edge of the annular end face along the inner peripheral surface of the cylindrical metal part.

3. the metal part is a substantially cylindrical metal part, the end surface is an annular end surface surrounded by the circular inner circumference and the circular outer circumference as the ring shape, and the rubber is molded into an annular region as the band-like region extending along the annular shape, The molding burr removing step includes: an outer periphery scanning step of limiting a scanning area to an annular band area sandwiched between the circumference of an outer periphery scanning reference circle having a diameter larger than the diameter of the outer periphery of the annular area by a predetermined length and the outer periphery of the circular end face, and performing scanning with the laser beam; and an inner side scanning process for limiting the scanning area to an annular band area sandwiched between the circumference of an inner side scanning reference circle having a diameter smaller by a predetermined length than the diameter of the inner circumference of the annular area and the inner circumference of the circular end face, and performing scanning with the laser beam.

4. 4. The rubber molding method according to claim 3, wherein the metal part is a substantially cylindrical metal part having a total length in the longitudinal direction of 10 to 30 mm and a maximum diameter in a direction perpendicular to the longitudinal direction of 5 to 15 mm.

5. 5. The rubber molding method according to claim 4, wherein the unevenness forming step forms minute unevenness with a height difference of 0.01 to 1.00 mm on the end surface by the blasting process.

Images