JP7376788B2 - Rubber mold releasability evaluation method, evaluation jig, base stand, and evaluation jig used therein - Google Patents

Description

The present invention relates to a method for evaluating the mold releasability of rubber , an evaluation jig, a base stand, and an evaluation jig used therein. , a method for evaluating the releasability of rubber that can easily and efficiently determine the change in releasability over time when the rubber is repeatedly released from a vulcanization mold, etc., and an evaluation jig and base stand used for the same, as well as the evaluation This relates to tools for use.

Rubber products such as pneumatic tires are manufactured by vulcanizing unvulcanized rubber in a vulcanization mold. When the rubber product manufactured after vulcanization is removed from the vulcanization mold, if the rubber product (vulcanized rubber) is difficult to release from the vulcanization mold, problems such as rubber chipping occur. Such defects lead to poor appearance of the rubber product. Alternatively, if the rubber is chipped and becomes clogged in the vent hole of the vulcanization mold, work to clear the blockage is required, leading to a decrease in productivity.

When a vulcanizing mold is used repeatedly, dirt accumulates on the molding surface, and the mold releasability changes accordingly. Since vulcanization on a dirty molding surface will affect the quality of the rubber product, the molding surface is cleaned after a predetermined period or a predetermined number of vulcanizations. Therefore, understanding the change in mold releasability over time is useful for ensuring the quality of rubber products and determining appropriate cleaning timing for vulcanization molds. Furthermore, it is also useful to understand changes over time in the releasability (releasability) of vulcanized rubber not only from a vulcanizing mold but also from, for example, a vulcanizing bladder.

Although it is not a technology for evaluating the mold releasability of vulcanized rubber, for example, an evaluation method has been proposed for selecting vulcanized adhesives with low mold contamination that are suitable for manufacturing rubber-metal composites (patented). (See Reference 1). In this evaluation method, unvulcanized rubber is vulcanized and bonded to the surface of a metal substrate that has undergone a predetermined adhesive treatment, and then the vulcanized rubber is peeled at a 90° angle to the surface of the metal substrate to determine the peel strength. Measure. In other words, this evaluation method evaluates the adhesion between vulcanized rubber and metal, and is not a method for evaluating the releasability of rubber and metal that are in close contact with each other without adhesion. Nor is it a method for evaluating changes over time. To evaluate the adhesion of vulcanized rubber, the peel strength is often measured when the vulcanized rubber is peeled from a metal surface at an angle of 90°.

It takes a great deal of time and cost to repeatedly test a vulcanized rubber vulcanized in an actual vulcanization mold to release it from the vulcanization mold to understand changes in releasability. Therefore, there is room for improvement in understanding changes over time in mold release properties (peelability) when releasing rubber that is in close contact without adhering to a vulcanization mold or the like.

Japanese Patent Application Publication No. 2002-243629

The purpose of the present invention is to easily and easily check the change in releasability over time when vulcanized rubber is repeatedly released from a vulcanization mold, etc. by repeatedly performing a tensile process that more reliably separates the rubber from the target surface. It is an object of the present invention to provide a method for evaluating rubber mold releasability that can be efficiently evaluated, and an evaluation jig, a base stand, and an evaluation jig used therein .

In order to achieve the above object, the method for evaluating the mold releasability of rubber according to the present invention uses an evaluation jig having a cylindrical body and a pressure member inserted into the cylindrical body. And,
The unvulcanized rubber is accommodated in the cylindrical body, the flat target surface of the base is arranged on one opening side of the cylindrical body, and the pressure member is inserted into the cylindrical body from the other opening side. , sandwiching the unvulcanized rubber between the target surface and the opposing surface of the pressure member facing the target surface, and moving at least one of the base and the pressure member in a direction in which they approach each other. By moving and heating the unvulcanized rubber while pressing it onto a predetermined area of the target surface , the evaluation jig is made to be in close contact with the target surface without adhering, and is closer to the target surface than the target surface. After forming a test specimen of a small piece of vulcanized rubber or semi-vulcanized rubber that is in close contact with the A tensile step is performed in which a vertical tensile force is applied to the entire contact surface of the test object with the target surface at once to peel the test object from the predetermined area, and the steps from the formation of the test object to the tension step are performed. The series of steps until completion is repeated by setting the predetermined area in the same area without changing the position to form a large number of test specimens, and the predetermined area after the tensile process for each test specimen is It is characterized by grasping the surface condition.

The rubber mold releasability evaluation jig and base stand of the present invention are the evaluation jig and the base stand used in the above-mentioned rubber mold releasability evaluation method, A contact area with the sulfurized rubber is set to be larger than a contact area of the target surface with the unvulcanized rubber.

Another jig for evaluating mold releasability of rubber according to the present invention is the evaluation jig used in the above-described method for evaluating mold releasability of rubber. It is characterized by having a grip part that grips the test specimen by inserting vulcanized rubber and being vulcanized.

Yet another rubber releasability evaluation jig of the present invention is the evaluation jig used in the above rubber mold releasability evaluation method, wherein the opposing surface or the inner periphery of the cylindrical body It is characterized in that it has an adhesive layer or a friction-increasing treated layer in the contact range of the surface with the unvulcanized rubber.

According to the rubber mold releasability evaluation method of the present invention, the unvulcanized rubber is sandwiched between the target surface and the opposing surface, and the unvulcanized rubber is heated in the cylindrical body. The test specimen can be stably formed. By performing a tensile process in which a vertical tensile force is applied to the entire contact surface of the molded test specimen with the target surface at once and the test specimen is peeled from the predetermined area, it is possible to make the actual rubber product. In the manufacturing process, the conditions are approximated to make it most difficult for the rubber to release from the vulcanization mold. Since the test specimen adheres more strongly to the evaluation jig than to the target surface, the test specimen can be more reliably peeled from the predetermined area in the tensioning step.

Then, a series of processes from forming the test specimen to completing the tensioning process are repeated by setting the predetermined area in the same area without changing the position, thereby forming a large number of test specimens. The actual manufacturing process of repeatedly releasing the vulcanization mold from the vulcanization mold can be easily reproduced. By checking the surface condition of the predetermined area after each of the tensile processes for a large number of test specimens, it is possible to efficiently check changes over time in the releasability of the rubber.

According to the rubber releasability evaluation jig and base stand of the present invention, the contact area of the opposing surface with the unvulcanized rubber is set to be larger than the contact area of the target surface with the unvulcanized rubber. This makes it easier to reliably separate the test specimen from the predetermined area. Further, according to the jig for evaluating the mold releasability of rubber of the present invention, the unvulcanized rubber enters the inner circumferential surface of the cylindrical body and is vulcanized, thereby gripping the test piece. With this, it becomes easier to reliably separate the test specimen from the predetermined area. Alternatively, if an adhesive layer or a friction increasing treatment layer is provided on the opposing surface or the inner circumferential surface of the cylindrical body in a contact range with the unvulcanized rubber, the test specimen can be reliably peeled from the predetermined area. Become.

FIG. 2 is an explanatory diagram illustrating a rubber releasability evaluation device as seen from the front. FIG. 2 is an explanatory diagram illustrating a part of the evaluation device of FIG. 1 in plan view. FIG. 2 is an explanatory diagram illustrating an enlarged vertical cross-sectional view of the evaluation jig held in the holder at the preparation position. FIG. 3 is an explanatory diagram illustrating, in a front view, a process of moving unvulcanized rubber together with an evaluation jig from a holder at a preparation position to a base table where heating is performed. FIG. 2 is an explanatory diagram illustrating, in a longitudinal cross-sectional view, a process of heating unvulcanized rubber to form a test body. FIG. 2 is an explanatory diagram illustrating a tensile process in which a tensile force is applied to a formed test specimen in a vertical cross-sectional view. FIG. 7 is an explanatory diagram illustrating the lower end of a test piece formed using another evaluation jig in a vertical cross-sectional view. FIG. 7 is an explanatory diagram illustrating the lower end of a test piece formed using yet another evaluation jig in a vertical cross-sectional view. FIG. 7 is an explanatory diagram illustrating the lower end of a test piece formed using yet another evaluation jig in a vertical cross-sectional view. FIG. 3 is an explanatory diagram illustrating, in a front view, a process of grasping the surface state of a predetermined area of the target surface after a tensioning process and a process of moving the test specimen together with the evaluation jig to a holder at a storage position. FIG. 7 is an explanatory diagram illustrating a process of moving the holding arm to the holder in the preparation position as seen from the front. FIG. 2 is an explanatory diagram schematically illustrating changes over time in the surface state of a predetermined area of the target surface. FIG. 3 is a graph diagram illustrating a change over time in the amount of dirt deposited on the surface of a predetermined area of the target surface. FIG. 2 is a graph diagram illustrating the change over time in the fracture strength of the interface between the rubber and the target surface in a tensile process. It is an explanatory view illustrating a part of another mold releasability evaluation device in longitudinal cross-sectional view. FIG. 16 is an explanatory diagram illustrating, in a longitudinal cross-sectional view, the step of heating the unvulcanized rubber of FIG. 15 to form a test specimen. FIG. 17 is an explanatory diagram illustrating, in a longitudinal cross-sectional view, a tensioning step in which a tensile force is applied to the test specimen in FIG. 16;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for evaluating the releasability of rubber of the present invention , the jig for evaluating releasability, the base stand, and the jig for evaluating releasability used in this evaluation method of the present invention will be described below based on the embodiment shown in the drawings.

In the rubber mold release property evaluation method of the present invention, a rubber mold release property evaluation device 1 (hereinafter referred to as evaluation device 1) illustrated in FIGS. 1 and 2 is used. This evaluation device 1 includes a releasability evaluation jig 7 (hereinafter referred to as evaluation jig 7) of the present invention. Then, using the evaluation jig 7, the unvulcanized rubber 11A is repeatedly heated in a predetermined area of the flat target surface 10a of the base 10 without changing the position of the predetermined area, and the vulcanized rubber is heated. A large number of test specimens 11 are formed. Further, using the evaluation jig 7, a tensile process is performed in which each test specimen 11 is peeled off from a predetermined area of the target surface 10a. Then, after the tensile process of each test specimen 11, the range and amount of dirt X adhering to a predetermined area of the target surface 10a are acquired by the surface grasping means 15 to grasp the surface condition. In the present invention, the test specimen 11 is not limited to completely vulcanized rubber, but includes rubber that is not completely vulcanized (so-called semi-vulcanized state). That is, the test specimen 11 may be made of rubber that is in a state where elastic deformation is dominant, rather than a highly fluid state where the rubber deforms excessively plastically when a tensile force is applied in a tensioning process described later. Note that the actuators 3 and 13, the measuring device 6, the surface grasping means 15, and the like are omitted and not shown in FIG.

In addition to the evaluation jig 7, this evaluation apparatus 1 includes a base 10 having a flat target surface 10a, a heating mechanism 12 that heats unvulcanized rubber 11A to form a test specimen 11, and a test specimen 11. The apparatus includes a tensioning mechanism 2 that performs a tensioning process on the target surface 10a, a surface grasping means 15 that grasps the surface condition of a predetermined area of the target surface 10a, and a conveyance mechanism 4. In this embodiment, the target surface 10a is a metal surface. Furthermore, the evaluation device 1 includes a measuring device 6, a control section 16, and a calculation section 17, which measure the breaking strength F of the interface between the test specimen 11 and the target surface 10a (predetermined area) during the tensile process. A computer is used as the control section 16 and the calculation section 17.

This embodiment includes a holding block 10b that is detachably connected to the top of the base 10. The holding block 10b has a through hole 10c extending vertically. This base stand 10 and holding block 10b function as a vulcanization mold.

Holders 5A and 5B are installed at a predetermined preparation position and a predetermined storage position, respectively, which are spaced apart from the position where the base 10 is installed. A large number of holding holes 5h are formed in the holders 5A and 5B, and one holder 5A holds the unvulcanized rubber 11A, and the other holder 5B holds the test specimen 11 after the tensile process.

In this embodiment, an evaluation jig 7 illustrated in FIG. 3 is used. The evaluation jig 7 includes a cylindrical body 9 and a pressure member 8 inserted into the cylindrical body 9. The unvulcanized rubber 11A is housed in a cylindrical body 9. Unvulcanized rubber 11A is placed on the lower end opening 9b side of the cylindrical body 9, and a cylindrical pressure member 8 is inserted from the upper end opening 9a side. An engaging portion 9c is formed at the upper end of the cylindrical body 9 and passes through the peripheral wall. The engaging portion 9c may be a groove or a depression without penetrating the peripheral wall of the cylindrical body 9. The outer circumferential surface of the pressure member 8 is formed to be in close contact with the inner circumferential surface of the cylindrical body 9.

The cylindrical body 9 is not limited to a cylindrical shape, but can also have other shapes such as a rectangular cylindrical shape. The pressure member 8 is not limited to a cylindrical shape, but can also have another shape that matches the shape of the cylindrical body 9. The lower end surface of the pressure member 8 is a facing surface 8a facing the unvulcanized rubber 11A. The opposing surface 8a has a larger surface area than the opposing target surface 10a by having a large number of unevenness. That is, the opposing surface 8a is intentionally set to have a large contact area with the unvulcanized rubber 11A.

The size of the unvulcanized rubber 11A is, for example, approximately several centimeters in outer diameter and height (length, width, and height dimensions are several centimeters). Note that the test specimen 11 formed by heating the unvulcanized rubber 11A also has approximately the same size as the unvulcanized rubber 11A. The state shown in FIG. 3 is obtained by inserting the unvulcanized rubber 11A from the lower end opening 9b of the cylindrical body 9 and inserting the pressure member 8 from the upper end opening 9a. The unvulcanized rubber 11A adheres to the inner peripheral surface and the opposing surface 8a of the cylindrical body 9 due to its adhesive properties.

The evaluation jig 7 illustrated in FIG. 3 containing the unvulcanized rubber 11A is in an upright state with the cylindrical body 9 inserted into the holding hole 5h of the holder 5A. A large number of evaluation jigs 7 are held in the holder 5A. It is preferable to use a material or coating on the bottom surface of the holding hole 5h to prevent the unvulcanized rubber 11A from adhering.

The evaluation jig 7 in which the test specimen 11 after the tensile process is accommodated is in an upright state with the cylindrical body 9 inserted into the holding hole 5h of the holder 5B. A large number of evaluation jigs 7 are held in the holder 5B. Since vulcanized rubber (test specimen 11) has no adhesive properties, there is no need to use any special material or coating on the bottom surface of the holding hole 5h of the holder 5B.

The conveyance mechanism 4 relatively moves the evaluation jig 7 containing the unvulcanized rubber 11A from a predetermined preparation position (holder 5A) to a predetermined area of the target surface 10a, The tool 7 is relatively moved from this predetermined area to a predetermined storage position (holder 5B). The transport mechanism 4 includes guide rails 4a and 4b that extend orthogonally in the horizontal direction and a moving body 4c. The moving body 4c moves along one guide rail 4a, and the other guide rail 4b moves in the extending direction of the guide rail 4b with respect to the moving body 4c, and these movements are driven by a servo motor or the like. .

In this embodiment, an actuator 3, which will be described later, is connected to and suspended from the other guide rail 4b. The actuator 3 can be moved to any planar position by the transport mechanism 4. The operation of the transport mechanism 4 is controlled by a control section 16. The transport mechanism 4 is not limited to the configuration illustrated in this embodiment, but can adopt various configurations. For example, a robot arm or the like can be used as the transport mechanism 4.

The heating mechanism 12 heats the unvulcanized rubber 11A housed in the evaluation jig 7 while pressing it against a predetermined area of the target surface 10a to form the test specimen 11. The heating mechanism 12 includes an actuator 13 and a heating device 14 . The rod 13a of the actuator 13 moves up and down, and the rod 13a that has advanced downward presses the upper end surface of the pressure member 8. As the actuator 13, various means can be used, such as a hydraulic cylinder, an air cylinder, a rod operated by a motor, and the like. The operation of the actuator 13 is controlled by a control section 16.

The heating device 14 heats the base 10 and the holding block 10b. Various means such as electricity and steam can be used for heating by the heating device 14. The heating device 14 vulcanizes or semi-vulcanizes the unvulcanized rubber 11A on the target surface 10a of the base 10, the opposing surface 8a of the pressure member 8, and the inner peripheral surface of the cylindrical body 9, which the unvulcanized rubber 11A contacts. It is heated to a predetermined heating temperature for vulcanization. The heating device 14 is controlled by a control section 16.

The tension mechanism 2 applies a tensile force to the test body 11 that attempts to peel the test body 11 housed in the evaluation jig 7 from the target surface 10a. Specifically, the tensile mechanism 2 applies a vertical tensile force to the entire contact surface of the test specimen 11 with the target surface 10a at once. The vertical direction in the present invention is a direction normal to the target surface 10a, but is substantially a direction of 90°±2° with respect to the target surface 10a, more preferably a direction of 90°±1°. Any direction is fine.

The tension mechanism 2 includes an actuator 3 and a holding arm 3c that is moved up and down by a rod 3a of the actuator 3. In this embodiment, a plate 3b is arranged below the rod 3a at a vertical interval, and the lower end of the rod 3a is connected to the upper plate 3b. A holding arm 3c is attached to the lower plate 3b. A measuring device 6 and an actuator 13 are sandwiched between the upper plate 3b and the lower plate 3b. Therefore, the holding arm 3c is connected to the rod 3a via the measuring device 6 and the actuator 13, which are sandwiched between the upper plate 3b and the lower plate 3b. The rod 13a of the actuator 13 passes through the lower plate 3b and can move up and down.

Two holding arms 3c are arranged at opposing positions, and the respective holding arms 3c are movable toward and away from each other. The number of holding arms 3c is not limited to two, but may be more than one, and may also be three, four, etc. The respective holding arms 3c are preferably arranged at equal intervals in the circumferential direction of a circle centered on the axis of the actuator 3. The operations of the actuator 3 and the holding arm 3c are controlled by a control section 16.

The measuring device 6 measures the breaking strength F at the interface with the target surface 10a of the test specimen 11 to which a tensile force is applied by the tensile mechanism 2. As the measuring device 6, for example, a load cell can be used. The breaking strength F of the interface between the test specimen 11 and the target surface 10a is basically the tensile strength (= tensile force/test specimen 11 and the target surface 10a). If the test piece 11 is damaged before the test piece 11 is peeled off from the target surface 10a, this breaking strength F is evaluated to be greater than the tensile strength when the test piece 11 is broken, or the test piece 11 is damaged. It can also be evaluated to be the same as the tensile strength when

The data measured by the measuring device 6 is input to the calculation section 17, and the above-mentioned breaking strength F is calculated by the calculation section 17. In this embodiment, the measuring device 6 is connected to the upper plate 3b and the actuator 13, but it can be installed at other positions as long as it can measure the above-mentioned breaking strength F.

In this embodiment, a digital camera for acquiring image data is used as the surface grasping means 15. As the surface grasping means 15, it is also possible to use, for example, a height sensor that detects the thickness of the dirt X attached to the target surface 10a. The data acquired by the surface grasping means 15 is input to the calculation section 17.

The control unit 16 and devices controlled by the control unit 16 are communicably connected by wire or wirelessly, and the arithmetic unit 17 and devices that input data to the arithmetic unit 17 are communicably connected by wire or wirelessly. ing.

The material of the target surface 10a (base stand 10) can be the same (equivalent) as the actual vulcanization mold, but for example, it is possible to set a reference material as an evaluation index in advance and use that reference material. Bye. The material of the opposing surface 8a (pressing member 8) and the cylindrical body 9 can be the same as or different from that of the target surface 10a. In addition to the target surface 10a, various coating agents that cover the molding surface of the vulcanization mold can also be used. Alternatively, various vulcanized rubbers such as those used in vulcanizing bladders may be used as the target surface 10a.

Hereinafter, an example of the procedure of the method for evaluating the mold releasability of vulcanized rubber of the present invention will be explained. Note that the evaluation procedure is the same when the test specimen 9 is semi-vulcanized rubber.

As illustrated in FIGS. 1 and 2, an evaluation jig 7 containing unvulcanized rubber 11A is prepared and placed upright in a holder 5A. Since a large number of test specimens 11 are formed, it is preferable to hold a large number of evaluation jigs 7 containing unvulcanized rubber 11A in the holder 5A in advance.

Next, after moving the holding arm 3c onto the evaluation jig 7 erected on the holder 5A by the moving mechanism 4, the rod 3a of the actuator 3 is advanced downward to move the holding arm 3c onto the cylindrical body 9. Move it down to the position. Next, the holding arms 3c are moved in a direction to approach each other, and each holding arm 3c is engaged with the engaging portion 9c of the cylindrical body 9.

Next, as illustrated in FIG. 4, the rod 3a of the actuator 3 is retreated upward, and the evaluation jig 7 with the holding arm 3c engaged is extracted from the holder 5A. Further, the actuator 3 is moved toward the base 10 together with the evaluation jig 7 by the moving mechanism 4. After positioning the moved evaluation jig 7 above the through hole 10c of the holding block 10b, the rod 3a of the actuator 3 is advanced downward and the evaluation jig 7 is inserted into the through hole 10c. The sulfur rubber 11A is placed on a predetermined area of the target surface 10a. The base 10 and the holding block 10b are heated to a predetermined heating temperature by the heating device 14. Although the heating temperature can be set arbitrarily, it is set, for example, to 40°C or higher, and when assuming tire vulcanization conditions, it is set to about 150°C to 200°C.

Next, as illustrated in FIG. 5, the rod 13a of the actuator 13 is advanced downward to press the upper end surface of the pressure member 8. As a result, by sandwiching the unvulcanized rubber 11A between the base 10 and the pressure member 8 and bringing the base 10 and the pressure member 8 relatively close to each other, the unvulcanized rubber 11A is pressed. Heat. Although it varies depending on the size of the unvulcanized rubber 11A, the heating time of the unvulcanized rubber 11A is, for example, within 10 minutes.

After the predetermined heating time has elapsed, the rod 13a of the actuator 13 is retreated upward to release the pressure on the upper end surface of the pressure member 8. While the unvulcanized rubber 11A is being heated, the holding arm 3c and the engaging portion 9c of the cylindrical body 9 are kept engaged. Thereby, the unvulcanized rubber 11A can be heated more stably.

By heating the unvulcanized rubber 11A, a small piece of test specimen 11 made of vulcanized rubber that is in close contact without adhering to the target surface 10a is formed. The test specimen 11 was in close contact with the opposing surface 8a of the pressure member 8 and the inner circumferential surface of the cylindrical body 9 without being bonded. In this embodiment, since the opposing surface 8a is set to have a larger surface area than the target surface 10a, the test specimen 11 is in tighter contact with the opposing surface 8a than with the target surface 10a. In addition, since the contact area between the test specimen 11 and the inner peripheral surface of the cylindrical body 9 is larger than the contact area between the test specimen 11 and the target surface 10a, the test specimen 11 is stronger against the cylindrical body 9 than the target surface 10a. It's in close contact.

Next, as illustrated in FIG. 6, the rod 3a of the actuator 3 is retracted upward to move the holding arm 3c upward. As a result, a tensile process is performed in which the test specimen 11 is pulled upward together with the evaluation jig 7.

As the tensile force applied to the test piece 11 gradually increases, the interface between the target surface 10a and the test piece 11 breaks (separates), so the tensile force at this time is measured by the measuring device 6. The value calculated by performing arithmetic processing in which the tensile force is divided by the contact area between the target surface 10a and the test specimen 11 by the calculation unit 17 is defined as the fracture strength F of the interface between the test specimen 11 and the target surface 10a.

That is, by moving at least one of the test specimen 11 and the base 10 in a direction away from each other, a vertical tensile force is applied at once to the entire contact surface of the test specimen 11 with the target surface 10a, The test specimen 11 is peeled off from a predetermined area of the target surface 10a. The test specimen 11 made of vulcanized rubber is in tighter contact with the evaluation jig 7 (the opposing surface 8a and the inner peripheral surface of the cylindrical body 9) than with the target surface 10a, so basically the test specimen 11 is in contact with the target surface 10a. It is peeled off at the surface 10a.

In this embodiment, tensile force is applied to the test specimen 11 by engaging the holding arm 3c with the engaging portion 9c and moving the cylindrical body 9 upward. Alternatively, an engagement part is provided at the upper end of the pressure member 8, and the holding arm 3c is engaged with the engagement part of the pressure member 8 and the engagement part 9c of the cylindrical body 9 to hold the pressure member 8. It is also possible to apply tensile force to the test specimen 11 by directly moving it upward.

By applying a vertical tensile force to the entire contact surface with the target surface 10a of the test specimen 11 at once, the vulcanized rubber is most difficult to release from the vulcanization mold in the actual manufacturing process of rubber products. The conditions are approximated. In tests in which adhesive strength is measured by peeling vulcanized rubber, the peel angle between the vulcanized rubber and the target surface tends to be unstable, making it difficult to measure adhesive strength while suppressing variations. On the other hand, in the present invention, the test body 11 (vulcanized rubber) is not peeled, but a tensile force is applied to the test body 11 as described above. Therefore, it is possible to stably measure the fracture strength of the interface between the test specimen 11 and the target surface 10a while suppressing variations.

In this evaluation jig 7, the contact area of the opposing surface 8a with the unvulcanized rubber 11A is set to be larger than the contact area of the target surface 10a with the unvulcanized rubber 11A. Therefore, in the tensile process, the test specimen 11 is not peeled off from the evaluation jig 7, and is easily easily peeled off from the predetermined area of the target surface 10a. Further, by using the cylindrical body 9, the test specimen 11 can be stably formed, and the tensile process can also be performed stably. The holding block 10b can be provided optionally, but when the holding block 10b is used, the evaluation jig 7 is stably held, so the test specimen 11 can be formed more stably, and the tensile process can also be performed. It can be done more stably.

As illustrated in FIG. 7, it is also possible to have a grip portion 8b on the opposing surface 8a of the pressure member 8, which grips the test specimen 11 by inserting the unvulcanized rubber 11A and vulcanizing it. In FIG. 7(A), a gripping portion 8b is formed in the shape of an arrow in a vertical cross-sectional view, and in FIG. 7(B), a gripping portion 8b is formed in an L-shape in a vertical cross-sectional view. In the tensioning process, the rubber vulcanized by the gripping part 8b is caught in the gripping part 8b. That is, since the test specimen 11 is physically engaged with and held by the opposing surface 8a, it becomes easy to reliably peel the test specimen 11 from a predetermined area of the target surface 10a without peeling it from the evaluation jig 7. . The grip portion 8b may have any shape as long as the specimen 11 is caught on the opposing surface 8a when a tensile force is applied to the specimen 11.

As illustrated in FIG. 8, it is also possible to have a grip portion 9d that grips the test specimen 11 by inserting unvulcanized rubber 11A into the inner circumferential surface of the cylindrical body 9 and vulcanizing it. In FIG. 8(A), the gripping portion 9d is arc-shaped in a vertical cross-sectional view, in FIG. 8(B), the gripping portion 9d is in a zigzag shape, and in FIG. 8(C), the gripping portion is L-shaped in a vertical cross-sectional view. 9d is formed. The rubber vulcanized by the gripping part 9d is caught in the gripping part 9d. That is, since the test specimen 11 is physically engaged with and held by the inner circumferential surface of the cylindrical body 9, the test specimen 11 can be reliably removed from a predetermined area of the target surface 10a without being separated from the evaluation jig 7. It is easy to peel off. The gripping portion 9d may have any shape as long as the specimen 11 is caught on the inner circumferential surface of the cylindrical body 9 when a tensile force is applied to the specimen 11.

As illustrated in FIG. 9(A), the pressure member 8 may have an adhesive layer 8c or a friction-increasing treated layer 8d on the opposing surface 8a. An adhesive capable of bonding the opposing surface 8a and the test specimen 11 (vulcanized rubber) is used for the adhesive layer 8c. The friction-increasing treated layer 8d increases the coefficient of friction between the opposing surface 8a and the test specimen 11 (vulcanized rubber). For example, a surface treatment agent containing aluminum oxide powder is applied as the friction increasing treatment layer 8d. The opposing surface 8a and the test specimen 11 are firmly joined by the adhesive layer 8c. In addition, the friction-increasing treated layer 8d makes it more difficult for the opposing surface 8a and the test specimen 11 to separate from each other. Accordingly, it becomes easier to reliably peel the test specimen 11 from a predetermined area of the target surface 10a without peeling it from the evaluation jig 7.

As illustrated in FIG. 9(B), the cylindrical body 8 may have an adhesive layer 9e or a friction-increasing treated layer 9f in the contact range with the unvulcanized rubber 11A on the inner circumferential surface of the cylindrical body 8. An adhesive capable of bonding the inner peripheral surface of the cylindrical body 9 and the test specimen 11 (vulcanized rubber) is used for the adhesive layer 9e. The friction increasing treatment layer 9f increases the coefficient of friction between the inner peripheral surface of the cylindrical body 9 and the test specimen 11 (vulcanized rubber). For example, a surface treatment agent containing aluminum oxide powder or the like is applied as the friction increasing treatment layer 9f. The inner peripheral surface of the cylindrical body 9 and the test specimen 11 are firmly joined by the adhesive layer 9e. Furthermore, the friction increasing treatment layer 9f makes it more difficult for the inner circumferential surface of the cylindrical body 9 and the test specimen 11 to separate from each other. Accordingly, it becomes easier to reliably peel the test specimen 11 from a predetermined area of the target surface 10a without peeling it from the evaluation jig 7.

After the tension process is completed, as illustrated in FIG. 10, the test specimen 11, which has been moved upward together with the evaluation jig 7 and pulled out from the through hole 10c, is moved toward the holder 5B by the moving mechanism 4. After the evaluation jig 7 is positioned above the holding hole 5h of the holder 5B, the rod 3a of the actuator 3 is advanced downward to insert the evaluation jig 7 into the holding hole 5h. As a result, the evaluation jig 7 is erected in the holding hole 5h, and the test specimen 11 is held by the holder 5B.

Further, after the test specimen 11 is pulled upward from the through hole 10c, the surface grasping means 15 is positioned above the through hole 10c by an appropriate means. Thereafter, the surface condition of a predetermined area of the target surface 10a is grasped by the surface grasping means 15.

The moving mechanism 4 that has moved the test specimen 11 to the holder 5B at the storage position moves the holding arm 3c toward the holder 5A at the preparation position, as illustrated in FIG. Thereafter, the cylindrical body 9 of the evaluation jig 7 containing the newly heated unvulcanized rubber 11A is engaged with the holding arm 3c to form the above-mentioned test specimen 11 and the formed test specimen 11. The above-described tensile process is repeated.

That is, a large number of test specimens 11 are formed by repeating a series of processes from the formation of the test specimen 11 described above to the completion of the tensioning process while setting the predetermined area in the same area without changing the position. By continuously repeating this series of steps, it is possible to easily reproduce the actual manufacturing process in which vulcanized rubber is repeatedly released from a vulcanization mold.

By forming a large number of test specimens 11, rubber components and components of compounding agents contained in the rubber gradually adhere to the target surface 10a and accumulate as dirt X. Therefore, when the surface condition of a predetermined area of the target surface 10a after the tensile process for each test specimen 11 is grasped by the surface grasping means 15, the surface condition is as shown in FIGS. 12(A) and 12(B). , (C). That is, the range of dirt X gradually widens (the amount V of dirt X accumulated gradually increases).

By calculating the change over time in the accumulated amount V of dirt X using the calculation unit 17, the results illustrated in FIG. 13 can be obtained. Since the accumulation of dirt X is accelerated in a short period of time, it is possible to efficiently grasp the change over time in the releasability of the rubber forming the test specimen 11. The characteristics of the change over time in the amount of accumulated dirt This will be advantageous in determining the appropriate cleaning timing for vulcanization molds. It also greatly contributes to speeding up the development work of rubber compositions with improved mold release properties.

Further, by calculating the above-mentioned change over time in the breaking strength F using the calculation unit 17, the results illustrated in FIG. 14 can be obtained. This breaking strength F tends to increase as the accumulated amount V of dirt It can also be evaluated.

In the early stage when the number of vulcanizations is small, it can be determined that the larger the breaking strength F is, the worse the mold releasability of the test specimen 11 is, and the smaller the breaking strength F is, the better the mold releasability is. On the other hand, if the change (increase) in the breaking strength F is small even when the number of vulcanizations increases, it can be evaluated that the change over time in the amount V of dirt X accumulated is small and the change in mold releasability is small. If the change (increase) in breaking strength F becomes excessive as the number of times of vulcanization increases, it can be evaluated that the change over time in the amount V of deposited dirt X is large and the change in mold releasability is large.

The speed at which the tensile force is applied to the test specimen 11 can be the same (equivalent) to the actual speed at which the vulcanization mold is released from the actually vulcanized rubber product, but for example, the speed at which the vulcanization mold is released from the vulcanized rubber product may be the same (equivalent); It is sufficient to set a reference speed as an evaluation index within the range of .

The evaluation device 1 illustrated in FIG. 15 differs from the evaluation device 1 described above in that the base 10 and the holding arm 3c are engaged with each other, and the base Move 10. That is, without moving the unvulcanized rubber 11A, the base 10 is moved to the position of each unvulcanized rubber 11A, and the test specimens 11 are formed and the tensile process is performed on each of the formed specimens 11. conduct. Other procedures are generally the same as in the previous embodiment.

A pressure member 8 is inserted from the lower end opening 9b side of the cylindrical body 9 of the evaluation jig 7 installed upright in the holder 5A, and unvulcanized rubber 11A is accommodated at the upper end opening 9a side. The unvulcanized rubber 11A is accommodated in the cylindrical body 9 without protruding upward from the upper end opening 9a. The cylindrical body 9 and the pressure member 8 are detachably fixed to the holder 5A by screwing or the like. The base 10 is heated to a predetermined heating temperature by a heating device 14.

To form the test specimen 11, as illustrated in FIG. 16, the rod 13a of the actuator 13 is advanced downward to press the base 10 downward. Along with this, the target surface 10a of the base 10 presses the unvulcanized rubber 11A. Thereby, the unvulcanized rubber 11A is sandwiched between the base 10 and the pressure member 8, and the unvulcanized rubber 11A is heated while being pressed.

After the test specimen 11 is formed, as illustrated in FIG. 17, the rod 13a is retreated upward to release the pressure on the base 10. Then, the rod 3a of the actuator 3 is retreated upward, and the base 10 is moved upward by the holding arm 3c. As the base 10 moves upward, a tensile force in the vertical direction is applied to the entire contact surface of the test specimen 11 with the target surface 10a at once, and the test specimen 11 is peeled off from a predetermined area of the target surface 10a. . In this way, the tensile process is performed. A large number of test bodies 11 are formed by repeating a series of processes from the formation of the test body 11 to the completion of the tensile process by setting the predetermined area in the same area without changing the position.

Then, the surface condition of a predetermined area of the target surface 10a after the tensile process for each test specimen 11 is grasped by the surface grasping means 15. Furthermore, during the tensile process for each test piece 11, the breaking strength F of the interface between the test piece 11 and the target surface 10a is measured by the measuring device 6.

1 Evaluation device 2 Tension mechanism 3 Actuator 3a Rod 3b Plate 3c Holding arm 4 Transport mechanism 4a, 4b Guide rail 4c Moving body 5A, 5B Holder 5h Holding hole 6 Measuring device (load cell)
7 Evaluation jig 8 Pressure member 8a Opposing surface 8b Gripping portion 8c Adhesive layer 8d Friction increasing treatment layer 9 Cylindrical body 9a Upper end opening 9b Lower end opening 9c Engagement portion 9d Gripping portion 9e Adhesive layer 9f Friction coefficient increasing treatment layer 10 Base 10a Flat target surface 10b Holding block 10c Through hole 11 Test object 11A Unvulcanized rubber 12 Heating mechanism 13 Actuator 13a Rod 14 Heating device 15 Surface grasping means 16 Control section 17 Computing section X Dirt

Claims (7)

A method for evaluating mold releasability of rubber using an evaluation jig having a cylindrical body and a pressure member inserted into the cylindrical body, the method comprising:
The unvulcanized rubber is accommodated in the cylindrical body, the flat target surface of the base is arranged on one opening side of the cylindrical body, and the pressure member is inserted into the cylindrical body from the other opening side. , sandwiching the unvulcanized rubber between the target surface and the opposing surface of the pressure member facing the target surface, and moving at least one of the base and the pressure member in a direction in which they approach each other. By moving and heating the unvulcanized rubber while pressing it onto a predetermined area of the target surface , the evaluation jig is made to be in close contact with the target surface without adhering, and is closer to the target surface than the target surface. After forming a test specimen of a small piece of vulcanized rubber or semi-vulcanized rubber that is in close contact with the A tensile step is performed in which a vertical tensile force is applied to the entire contact surface of the test object with the target surface at once to peel the test object from the predetermined area, and the steps from the formation of the test object to the tension step are performed. The series of steps until completion is repeated by setting the predetermined area in the same area without changing the position to form a large number of test specimens, and the predetermined area after the tensile process for each test specimen is A method for evaluating the mold releasability of rubber, which is characterized by understanding the surface condition. The method for evaluating mold releasability of rubber according to claim 1, wherein the breaking strength of the interface between the test body and the target surface is measured during the tensile step for each of the test bodies. The evaluation jig and the base used in the rubber releasability evaluation method according to claim 1 or 2,
A jig and a base for evaluating mold releasability of rubber, characterized in that a contact area of the opposing surface with the unvulcanized rubber is set larger than a contact area of the target surface with the unvulcanized rubber. . The jig and base stand for evaluating mold releasability of rubber according to claim 3, wherein the opposing surface has a grip portion that grips the test specimen by entering the unvulcanized rubber and being vulcanized. . The mold releasability of the rubber according to claim 3 or 4, wherein the inner circumferential surface of the cylindrical body has a grip portion that grips the test specimen by inserting the unvulcanized rubber and being vulcanized. Evaluation jig and base . The evaluation jig used in the rubber releasability evaluation method according to claim 1 or 2,
A tool for evaluating mold releasability of rubber, characterized in that the inner circumferential surface of the cylindrical body has a gripping part that grips the test specimen by inserting the unvulcanized rubber and being vulcanized. Ingredients. The evaluation jig used in the rubber releasability evaluation method according to claim 1 or 2,
A jig for evaluating mold releasability of rubber, comprising an adhesive layer or a friction-increasing treated layer on the opposing surface or the inner peripheral surface of the cylindrical body in a contact range with the unvulcanized rubber. .

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