JP7376789B2 - Rubber pullability evaluation method and device - Google Patents

Description

The present invention relates to a method and apparatus for evaluating the pullability of rubber, and more particularly, to a method and apparatus for evaluating pullability of rubber, and more particularly, to a rubber pullout method that allows easy and efficient grasping of changes in pullability over time when rubber is repeatedly pulled out from the recesses of a vulcanization mold, etc. The present invention relates to a sex evaluation method and device.

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. If the vulcanized rubber that has been cured in the recesses of the vulcanization mold cannot be pulled out of the recesses and is chipped, the rubber product will have a poor appearance. Alternatively, if the vulcanized rubber is chipped and clogged in a concave portion such as a vent hole, an operation to clear the clog is required, leading to a decrease in productivity.

As the vulcanization mold is used repeatedly, dirt accumulates on the side surfaces of the recessed portions of the vulcanization mold, and the pullability of the vulcanized rubber changes accordingly. Therefore, understanding the change in pullability over time is useful for ensuring the quality of rubber products and determining appropriate cleaning timing for vulcanization molds. In addition, it is also useful to understand changes over time in the pullability of vulcanized rubber from recesses other than vulcanization molds, such as vulcanization bladders.

Although it is not a technology for evaluating the pullability of vulcanized rubber, an evaluation method has been proposed for selecting vulcanized adhesives with low mold contamination that are suitable for manufacturing rubber-metal composites (Patent Document (see 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 pullability of rubber and metal that are in close contact with each other without adhesion, but rather evaluates the change in pullability over time. There is no way to evaluate it.

It takes a lot of time and cost to repeatedly perform tests to pull out vulcanized rubber that has been vulcanized in an actual vulcanization mold from the recesses of the vulcanization mold to determine changes in pullability. Therefore, there is room for improvement in understanding changes over time in the pullability when pulling rubber out of the recesses of a vulcanization mold or the like.

Japanese Patent Application Publication No. 2002-243629

An object of the present invention is to provide a method and apparatus for evaluating the pullability of rubber, which can easily and efficiently grasp changes in pullability over time when rubber is repeatedly pulled out from the recesses of a vulcanization mold or the like.

In order to achieve the above object, the method for evaluating the pullability of rubber according to the present invention involves heating an unvulcanized rubber housed in a cylindrical body while being pushed into a recess of a mold member by a pressure member inserted into the cylindrical body. By doing so, a small piece test piece made of vulcanized rubber or semi-vulcanized rubber having a protrusion that is in close contact with the side surface of the recessed portion without adhesion is formed, and a small piece of the test piece other than the side surface is formed. In a region where the mold member faces, a release layer is interposed between the test specimen and the mold member, and at least one of the test specimen and the mold member is moved in a direction away from each other. A tensile step is performed in which a tensile force is applied to the test specimen to pull out the protrusion from the recess and the test specimen is peeled from the mold member, and a series of steps from formation of the test specimen to completion of the tension step is performed. The above process is repeated using the same recess to form a large number of test specimens, and during the tensile process for each test specimen, the fracture strength of the interface between the protrusion and the side surface is measured. Features.

In order to achieve the above object, the rubber pullability evaluation device of the present invention includes a cylindrical body, a pressure member inserted into the cylindrical body, a mold member having a recess, and a rubber extractor housed in the cylindrical body. Vulcanized rubber having a protrusion that is heated while being pushed into the recess by the pressure member inserted into the cylindrical body, and is in close contact with the side surface of the recess without adhering. or a heating mechanism for forming a test piece of a small piece of semi-vulcanized rubber; and a mold release interposed between the test piece and the mold member in a region other than the side surface where the test piece and the mold member face each other. After forming the layer and the test body, at least one of the test body and the mold member is moved in a direction away from each other, and a tensile force is applied to the test body to pull out the protrusion from the recess. a tensioning mechanism that performs a tensioning step of peeling the test specimen from the mold member; a measuring device; and the cylinder, in which the unvulcanized rubber is accommodated on one opening side and the pressure member is inserted from the other opening side. The cylindrical body, in which the test specimen is accommodated on one opening side and the pressure member is inserted on the other opening side, is moved from the recess to a predetermined storage position. and a conveyance mechanism that moves the test specimens relative to each other, and the series of processes from the formation of the test specimens to the completion of the tensioning process is repeatedly performed using the same recessed portion, so that a large number of the specimen specimens are formed. It is characterized in that the breaking strength of the interface between the protrusion and the side surface is measured by the measuring device during the tensile process for each.

According to the present invention, a test piece of a small piece of vulcanized rubber or semi-vulcanized rubber having a protrusion that is in close contact with the side surface of the recessed portion without adhesion is formed, and the test piece other than the side surface of the recess is formed. In the region where the body and the mold member face each other, a release layer is interposed between the test specimen and the mold member, and the tension process is performed, so that the rubber The conditions are such that it is possible to detect the pure tensile force required when pulling the material out of the vulcanization mold. By forming a large number of test specimens with a setting in which the series of processes from forming the test specimen to completing the tensioning process are repeated using the same recess, the rubber can be repeatedly drawn from the recess of the vulcanization mold. The actual manufacturing process of drawing can be easily reproduced. After each of the tensile processes for a large number of test specimens, the breaking strength of the interface between the protrusion and the side surface is measured using the measuring device, thereby efficiently determining the pullability of the rubber based on the measured data. It is possible to understand changes over time.

FIG. 2 is an explanatory diagram illustrating an embodiment of a rubber pullability 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 longitudinal cross-sectional view of unvulcanized rubber held in a holder in a preparation position. FIG. 3 is an explanatory diagram illustrating a process of moving unvulcanized rubber from a holder at a preparation position to a mold member where heating is performed, as seen from the front. 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. It is an explanatory view illustrating a process of heating unvulcanized rubber by another method and forming a test piece in a longitudinal cross-sectional view. FIG. 8 is an explanatory diagram illustrating, in a longitudinal cross-sectional view, a tensile process of applying a tensile force to the test specimen formed by the method of FIG. 7; FIG. 3 is an explanatory diagram illustrating a process of moving a test specimen after a tensioning process to a holder at a storage position in a front view. 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. 3 is a graph diagram illustrating a change over time in the breaking strength of the interface between the rubber and the side surface of the recess in a tensile process. It is an explanatory view illustrating a part of another embodiment of a pullability evaluation device in longitudinal cross-sectional view. FIG. 13 is an explanatory diagram illustrating, in a longitudinal cross-sectional view, the step of heating the unvulcanized rubber of FIG. 12 to form a test specimen. FIG. 14 is an explanatory diagram illustrating, in a vertical cross-sectional view, a tensile process for applying a tensile force to the test specimen in FIG. 13;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The rubber pullability evaluation method and apparatus of the present invention will be explained below based on the embodiment shown in the drawings.

The embodiment of the rubber pullability evaluation device 1 (hereinafter referred to as evaluation device 1) illustrated in FIGS. 1 and 2 uses the same recess 9 of the mold member 8 to repeatedly heat the unvulcanized rubber R. A large number of small pieces of test specimens Rc made of vulcanized rubber having protrusions t that are in close contact without being bonded to the side surfaces of the recess 9 are formed. In addition, a tensile process is performed on each of the formed test specimens Rc in which the protrusion t is pulled out from the recess 9 and peeled off from the mold member 8. Then, during the tensile process of each test specimen Rc, the breaking strength of the interface between the protrusion t and the side surface of the recess 9 is measured. In the present invention, the test specimen Rc is not limited to completely vulcanized rubber, but includes rubber in a completely unvulcanized state (so-called semi-vulcanized state). That is, the test specimen Rc may be a rubber in which elastic deformation is predominant, rather than a highly fluid state in which excessive plastic deformation occurs when a tensile force is applied in the tensile process described later. Note that the actuators 3, 12, measuring device 6, etc. are omitted and not shown in FIG.

This evaluation device 1 heats a cylindrical body 10, a pressure member 7 inserted into the cylindrical body 10, a mold member 8 having a recess 9, and an unvulcanized rubber R to form a test specimen Rc. It includes a heating mechanism 11, a tensioning mechanism 2 that performs a tensioning process on the test specimen Rc, a measuring device 6, a transport mechanism 4, and a mold release layer 14. In this embodiment, the side surfaces of the recess 9 are metal surfaces. Furthermore, the evaluation device 1 includes a control section 15 and a calculation section 16. A computer is used as the control section 15 and the calculation section 16.

In this embodiment, the recess 9 is a circular hole that vertically passes through the mold member 8, but the recess 9 is not limited to a circular hole, and may be a polygonal hole, for example, or a depression that does not penetrate through the mold member 8. Alternatively, a groove (slit) or the like may be used as the recess 9.

A holding block 8A is provided on the mold member 8 and is detachably connected thereto. A mold release layer 14 is sandwiched between the mold member 8 and the holding block 8A. The holding block 8A has a through hole 8c extending vertically. This mold member 8 and holding block 8A 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 mold member 8 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 R, and the other holder 5B holds the test specimen Rc after the tensile process.

In this embodiment, as illustrated in FIG. 3, the unvulcanized rubber R is housed in a cylindrical body 10. Unvulcanized rubber R is arranged on the lower end opening 10b side of the cylindrical body 10, and a cylindrical pressure member 7 is inserted from the upper end opening 10a side. An engaging portion 10c is formed at the upper end of the cylindrical body 10, passing through the peripheral wall. The outer circumferential surface of the pressure member 7 is formed to be in close contact with the inner circumferential surface of the cylindrical body 10.

The cylindrical body 10 is not limited to a cylindrical shape, but can also have other shapes such as a rectangular cylindrical shape. The pressure member 7 is not limited to a cylindrical shape, but can also have another shape that matches the shape of the cylindrical body 10. The lower end surface of the pressure member 7 is a facing surface 7a facing the unvulcanized rubber R. Although the facing surface 7a can be a flat surface, in this embodiment, it has many irregularities so that the contact area with the unvulcanized rubber R is intentionally set to be large.

The size of the unvulcanized rubber R is, for example, approximately several centimeters in outer diameter and height (length, width, and height dimensions are several centimeters). The test specimen Rc formed by heating the unvulcanized rubber R has a protrusion t, but has substantially the same volume as the unvulcanized rubber R. The state shown in FIG. 3 is obtained by inserting the unvulcanized rubber R from the lower end opening 10b of the cylindrical body 10 and inserting the pressure member 7 from the upper end opening 10a. The unvulcanized rubber R adheres to the inner peripheral surface and the opposing surface 7a of the cylindrical body 10 due to its adhesive properties.

The unvulcanized rubber R, the pressure member 7, and the cylindrical body 10 shown in FIG. 3 are in an upright state with the cylindrical body 10 inserted into the holding hole 5h of the holder 5A. A large number of these integrated objects are held in the holder 5A. In addition, it is preferable to employ a material or coating that prevents the unvulcanized rubber R from adhering to the bottom surface of the holding hole 5h.

After the tensile process, the test specimen Rc, the pressure member 7, and the cylindrical body 10 are integrated into an upright state with the cylindrical body 10 inserted into the holding hole 5h of the holder 5B. A large number of these integrated objects are held in the holder 5B. If the protruding portion t is elongated, the specimen Rc will be in a bent state when inserted into the holding hole 5h and held. Since vulcanized rubber (test specimen Rc) 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 transport mechanism 4 relatively moves the unvulcanized rubber R from a predetermined preparation position (holder 5A) to the recess 9, and relatively moves the test specimen Rc from this recess 9 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 15. 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 11 heats the unvulcanized rubber R pushed into the recess 9 to form a test specimen Rc. The heating mechanism 11 includes an actuator 12 and a heating device 13. The rod 12a of the actuator 12 moves up and down, and the rod 12a that has advanced downward presses the upper end surface of the pressure member 7. As the actuator 12, 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 12 is controlled by a control section 15.

The heating device 13 heats the mold member 8 and the holding block 8A. Various means such as electricity and steam can be used for heating by the heating device 13. The heating device 13 vulcanizes or semi-vulcanizes the unvulcanized rubber R on the surface 8b of the mold member 8 facing the unvulcanized rubber R, the opposing surface 7a of the pressure member 7, and the inner peripheral surface of the cylindrical body 10. It is heated to a predetermined heating temperature to turn it into sulfur. The heating device 13 is controlled by a control section 15 .

The tensioning mechanism 2 applies a tensile force to the test specimen Rc to pull out the protrusion t from the recess 9 and peel off the test specimen Rc from the mold member 8 . Specifically, the tension mechanism 2 applies a tensile force to the test specimen Rc in a direction parallel to the depth direction of the recess 9 (a direction in which the protrusion t is simply pulled without substantially bending it).

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 12 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 12, which are sandwiched between the upper plate 3b and the lower plate 3b. The rod 12a of the actuator 12 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 operation of the actuator 3 and the holding arm 3c is controlled by a control section 15.

The measuring device 6 measures the breaking strength F at the interface between the protrusion t of the test specimen Rc to which a tensile force is applied by the tensile mechanism 2 and the side surface of the recess 9. As the measuring device 6, for example, a load cell can be used. This breaking strength F basically refers to the tensile strength when the protrusion t that is in close contact with the side surface of the recess 9 is peeled off from this side surface (= tensile force/contact area between the protrusion t and the side surface of the recess 9). It is. If the protrusion t is damaged before the protrusion t is peeled off from the side surface of the recess 9, the breaking strength F is evaluated to be greater than the tensile strength when the protrusion t is broken, or the protrusion t is It can also be evaluated as being the same as the tensile strength when broken.

The data measured by the measuring device 6 is input to the calculation section 16, and the above-mentioned breaking strength F is calculated by the calculation section 16. In this embodiment, the measuring device 6 is connected to the upper plate 3b and the actuator 12, but it can be installed at other positions as long as it can measure the breaking strength F mentioned above.

The mold release layer 14 is interposed between the test specimen Rc and the mold member 8 in a region other than the side surface of the recess 9 where the test specimen Rc and the mold member 8 face each other. In this embodiment, a release layer 14 is laminated on the surface 8b of the mold member 8. The release layer 14 inhibits close contact and adhesion between the mold member 8 and the test specimen Rc, which is vulcanized rubber. As the mold release layer 14, various resin films and resin coatings such as PET, PEN, and fluororesin can be used.

The control unit 15 and devices controlled by the control unit 15 are communicably connected by wire or wirelessly, and the arithmetic unit 16 and devices that input data to the arithmetic unit 16 are communicably connected by wire or wirelessly. ing.

The material of the mold member 8 can be the same (equivalent) as that of the actual vulcanization mold, but for example, a reference material used as an evaluation index may be set in advance and that reference material used. The materials of the opposing surface 7a (pressing member 7) and the cylindrical body 10 may be the same as or different from those of the mold member 8. The side surfaces of the recess 9 are not limited to metal surfaces, and the side surfaces of the recess 9 can also be formed using various coating agents that cover the molding surface of the vulcanization mold. Alternatively, the sides of the recess 9 can be formed of various vulcanized rubbers such as those used in vulcanizing bladders.

Hereinafter, a method for evaluating the pullability of a test specimen Rc made of vulcanized rubber using this evaluation apparatus 1 will be explained. Note that the evaluation procedure is the same when the test specimen Rc is semi-vulcanized rubber.

As illustrated in FIGS. 1 and 2, a cylindrical body 10 in which unvulcanized rubber R is accommodated in the lower end opening 10b side and a pressure member 7 is inserted from the upper end opening 10a side is prepared and placed in the holder 5A. have it set up. Since a large number of test specimens Rc are to be formed, it is preferable to hold a large number of such cylindrical bodies 10 in the holder 5A in advance.

Next, the moving mechanism 4 moves the holding arm 3c onto the cylindrical body 10 erected on the holder 5A, and then the rod 3a of the actuator 3 is advanced downward to move the holding arm 3c onto the cylindrical body 10. Move it down to the desired 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 10c of the cylindrical body 10.

Next, as illustrated in FIG. 4, the rod 3a of the actuator 3 is retreated upward to remove the cylindrical body 10 engaged with the holding arm 3c from the holder 5A. Further, the actuator 3 is moved toward the mold member 8 by the moving mechanism 4 together with the cylindrical body 10 in which the unvulcanized rubber R and the pressure member 7 are housed. After positioning the cylindrical body 10 above the through hole 8c of the holding block 8A, the rod 3a of the actuator 3 is advanced downward to insert the cylindrical body 10 into the through hole 8c. The unvulcanized rubber R accommodated in the cylindrical body 10 is thus positioned in the area of the surface 8b including the pre-formed recess 9, so that the cylindrical body 10 is placed on the surface 8b. The mold member 8 and the holding block 8A are heated to a predetermined heating temperature by the heating device 13. 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 12a of the actuator 12 is advanced downward to press the upper end surface of the pressure member 7. Thereby, the unvulcanized rubber R is heated while being pushed into the recess 9. Although it varies depending on the size of the unvulcanized rubber R, the heating time of the unvulcanized rubber R is, for example, within 10 minutes. A protrusion t is formed in the recess 9 and heated.

After the predetermined heating time has elapsed, the rod 12a of the actuator 12 is retreated upward to release the pressure on the upper end surface of the pressure member 7. While the unvulcanized rubber R is being heated, the holding arm 3c and the engaging portion 10c of the cylindrical body 10 are kept engaged. Thereby, the unvulcanized rubber R can be heated more stably.

By heating the unvulcanized rubber R, a small piece test specimen Rc made of vulcanized rubber having a protruding portion t that is in close contact with the side surface of the recess 9 without adhering is formed. Although this test specimen Rc is in close contact with the opposing surface 7a of the pressure member 7 and the inner peripheral surface of the cylindrical body 10 without being bonded, they may be bonded using an adhesive or the like. In addition to the mold release layer 14 being laminated on the surface 8b of the mold member 8, in this embodiment, the contact area between the opposing surface 7a and the test specimen Rc is the same as the contact area between the protrusion t and the side surface of the recess 9. Since it is set to be large compared to the area, the test specimen Rc is in even stronger contact with the opposing surface 7a than the mold member 8. In addition to the mold release layer 14 being laminated on the surface 8b of the mold member 8, the contact area between the test specimen Rc and the inner peripheral surface of the cylindrical body 10 is larger than that of the protrusion t and the side surface of the recess 9. Since the contact area is set larger than the contact area of , the test specimen Rc is in tighter contact with the cylindrical body 10 than with the mold member 8.

Next, as illustrated in FIG. 6, the rod 3a of the actuator 3 is retracted upward to move the holding arm 3c upward. Thereby, a tensile process is performed in which the test specimen Rc is pulled upward together with the cylindrical body 10 and the pressure member 7.

As the tensile force applied to the test specimen Rc gradually increases, the interface between the protrusion t and the side surface of the recess 9 breaks (separates), so the tensile force at this time is measured by the measuring device 6. The value calculated by dividing this tensile force by the contact area between the protrusion t and the side surface of the recess 9 by the calculation unit 16 is defined as the breaking strength F of the interface between the protrusion t and the side surface of the recess 9. do.

That is, by moving at least one of the test specimen Rc and the mold member 8 in a direction away from each other, a tensile force is applied to the test specimen Rc to pull out the protrusion t from the recess 9, and the test specimen Rc is moved away from the mold member 8. Peel it off. The test specimen Rc and the surface 8b of the mold member 8 are easily separated from each other by the mold release layer 14, and the specimen Rc made of vulcanized rubber is exposed to the opposing surface 7a and the inside of the cylindrical body 10 rather than the side surface of the recess 9. Since it is in strong contact with the circumferential surface, the protrusion t is basically pulled out from the recess 9 and the test specimen Rc is peeled off from the mold member 8.

A mold release layer 14 is interposed between the test body Rc and the mold member 8 in a region where the test body Rc and the mold member 8 face each other other than the side surface of the recess 9 . This provides conditions for detecting the pure tensile force required when pulling vulcanized rubber out of a vulcanization mold in the actual manufacturing process of rubber products. Although the holding block 8A can be omitted, if the holding block 8A is used, the test specimen Rc can be formed more stably, and the tensile process can also be performed more stably.

In this embodiment, tensile force is applied to the specimen 9 by engaging the holding arm 3c with the engaging portion 10c and moving the cylindrical body 10 upward. Alternatively, an engagement part is provided at the upper end of the pressure member 7, and the holding arm 3c is engaged with the engagement part of the pressure member 7 and the engagement part 10c of the cylindrical body 10 to hold the pressure member 7. It is also possible to apply tensile force to the test specimen 9 by directly moving it upward.

It is also possible to form the test body Rc by another method illustrated in FIGS. 7 and 8, and to perform a tensile process on the formed test body Rc.

As illustrated in FIG. 7, by connecting a holding block 8A having a vertically penetrating through hole 8c on top of the mold member 8, a portion defined by the through hole 8c and the surface 8b of the mold member 8 is formed into a recess 9. Use as. That is, a bottomed recess 9 with the surface 8b as the bottom is used. A release layer 14 is laminated on the surface 8b. It is sufficient that the release layer 14 exists at least in a range corresponding to the through hole 8c.

The rod 3a of the actuator 3 is advanced downward, and the cylindrical body 10, in which the unvulcanized rubber R is accommodated in the lower end opening 10b side and the pressure member 7 is inserted from the upper end opening 10a side, is inserted halfway through the through hole 8c. Insert it to the position shown below. The mold member 8 is heated to a predetermined heating temperature by a heating device 13.

In this state, the rod 12a of the actuator 12 is advanced downward to press the upper end surface of the pressure member 7. The pressurizing member 7 presses the unvulcanized rubber R to the bottom (surface 8b) of the recess 9 (through hole 8c) and heats it, making a small piece of test piece Rc of vulcanized rubber having a protrusion t. form. The protrusion t is in close contact with the side surface of the recess 9 (through hole 8c) without adhesive. A release layer 14 is interposed between the test body Rc and the mold member 8 in the region where the test body Rc and the mold member 8 face each other, except for the side surface of the recess 9 (through hole 8c).

When performing the tensioning process, as illustrated in FIG. 8, the rod 12a of the actuator 12 is retreated upward to release the pressure on the upper end surface of the pressure member 7. Then, the rod 3a of the actuator 3 is retreated upward to move the holding arm 3c upward. Thereby, the test specimen Rc is pulled upward together with the cylindrical body 10 and the pressure member 7, and a tensile force is applied to the test specimen Rc. Thereby, the protrusion t is pulled out from the recess 9 (through hole 8c), and the test specimen Rc is peeled off from the mold member 8. In the tensile process, the breaking strength F mentioned above is measured.

After the tensioning process, as illustrated in FIG. 9, the cylindrical body 10, in which the test specimen Rc is accommodated in the lower end opening 10b side and the pressure member 7 is inserted in the upper end opening 10a side, is moved upward to open the through hole. 8c and moved by the moving mechanism 4 toward the holder 5B. After positioning the cylindrical body 10 above the holding hole 5h of the holder 5B, the rod 3a of the actuator 3 is advanced downward to insert the cylindrical body 10 into the holding hole 5h. Thereby, the cylindrical body 10 is erected in the holding hole 5h, and the test specimen Rc is held by the holder 5B.

The moving mechanism 4 that has moved the test specimen Rc 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 engaging portion 10c of the cylindrical body 10 containing the newly heated unvulcanized rubber R is engaged with the holding arm 3c to form the above-mentioned test specimen Rc and the formed test specimen Rc. The above-described tensile process is repeated.

That is, the series of processes from the formation of the test specimen Rc described above to the completion of the tensioning process are repeated using the same recess 9 to form a large number of test specimens Rc. By repeating and continuously performing this series of steps, it is possible to easily reproduce the actual manufacturing process in which the vulcanized rubber is repeatedly pulled out and released from the recesses of the vulcanization mold.

By forming a large number of test specimens Rc, rubber components and components of compounding agents contained in the rubber gradually adhere to the side surfaces of the recesses 9 and accumulate as dirt X. Therefore, according to the present invention, the accumulation of dirt X can be accelerated in a short time.

Then, by calculating the above-mentioned change over time in the breaking strength F using the calculation unit 16, the results illustrated in FIG. 11 can be obtained. Since this breaking strength F tends to increase as the accumulated amount V of dirt X increases, the amount of accumulated dirt Changes in V over time can be evaluated. The characteristics of the change over time in the amount of deposited dirt This is advantageous in preventing the occurrence of vulcanization and determining the appropriate cleaning timing for the vulcanization mold. It also greatly contributes to speeding up the development work of rubber compositions with improved pullability.

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 pullout property of the test specimen Rc is, and the smaller the breaking strength F is, the better the drawing property 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 pullability 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 pullability is large. In the present invention, since the accumulation of dirt X is accelerated in a short time, it is possible to efficiently grasp the change over time in the pullability of the rubber forming the test specimen Rc.

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

Another embodiment of the evaluation device 1 illustrated in FIG. 12 differs from the previous embodiment in that the mold member 8 and the holding arm 3c are engaged with each other, and the unvulcanized rubber R held in the holder 5A is The mold member 8 is moved relative to the mold member 8. That is, the mold member 8 is moved to the position of each unvulcanized rubber R without moving the unvulcanized rubber R, and the test specimen Rc is formed and the tensile process is performed on each of the formed specimen Rc. conduct. Other procedures are generally the same as in the previous embodiment.

A pressure member 7 is inserted into the cylindrical body 10 erected in the holder 5A from the lower end opening 10b side, and unvulcanized rubber R is accommodated at the upper end opening 10a side. The unvulcanized rubber R is housed in the cylindrical body 10 without protruding upward from the upper end opening 10a. The cylindrical body 10 and the pressure member 7 are detachably fixed to the holder 5A by screwing or the like. The mold member 8 is heated to a predetermined heating temperature by a heating device 13. A recess 9 is formed in the mold member 8, and the surface 8b is covered with a release layer 14 except for the opening of the recess 9.

To form the test specimen Rc, as illustrated in FIG. 13, the rod 12a of the actuator 12 is advanced downward to press the mold member 8 downward. Along with this, the unvulcanized rubber R is pressed by the surface 8b of the mold member 8. As a result, the unvulcanized rubber R housed in the cylindrical body 10 is heated while being pushed into the recess 9 by the pressurizing member 7 inserted into the cylindrical body 10 to form the test specimen Rc having the protrusion t. Form.

After the test specimen Rc is formed, as illustrated in FIG. 14, the rod 12a is retreated upward to release the pressure on the mold member 8. Then, the rod 3a of the actuator 3 is retreated upward, and the holding arm 3c moves the mold member 8 upward to perform a tensioning process. As the mold member 8 moves upward, a tensile force is applied to the test specimen Rc, the protruding portion t is pulled out from the recess 9, and the test specimen Rc is peeled off from the mold member 8. A series of processes from the formation of the test specimen Rc to the completion of the tensile process are repeated using the same recess 9 to form a large number of test specimens Rc. During the tensile process for each test specimen Rc, the breaking strength F of the interface between the protrusion t and the side surface of the recess 9 is measured.

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 Pressure member 7a Opposing surface 8 Mold member 8A Holding block 8b Surface 8c Through hole 9 Recess 10 Cylindrical body 10a Upper end opening 10b Lower end opening 10c Engaging portion 11 Heating mechanism 12 Actuator 12a Rod 13 Heating machine 14 Release layer 15 Control Part 16 Calculation part R Unvulcanized rubber Rc Test specimen t Projection part

Claims (5)

By heating the unvulcanized rubber housed in the cylindrical body while pushing it into the recess of the mold member using a pressure member inserted into the cylindrical body, the unvulcanized rubber is brought into close contact with the side surface of the recess without adhesion. A test piece of a small piece of vulcanized rubber or semi-vulcanized rubber having a protruding portion is formed, and in an area other than the side surface where the test piece and the mold member face each other, the test piece and the mold member are By moving at least one of the test specimen and the mold member in a direction in which they are separated from each other with a release layer interposed between them, a tensile force is applied to the test specimen and the protrusion is A tensile process is performed in which the test specimen is peeled from the mold member by being pulled out of the recess, and a series of processes from the formation of the test specimen to the completion of the tension process are repeated using the same recess to perform a large number of tests. A method for evaluating pullability of rubber, comprising: forming a body, and measuring the breaking strength of an interface between the protrusion and the side surface during the tensile process for each of the test specimens. The recess is formed on the surface of the mold member, the unvulcanized rubber accommodated in the cylindrical body is positioned in a region of the surface including the recess, and the cylindrical body is placed on the surface. 2. The method for evaluating the pullability of rubber according to claim 1, wherein the unvulcanized rubber is heated while being pressed into the recess by the pressure member. 2. A holding block having a vertically penetrating through hole is connected on top of the mold member, and the test specimen is formed with the cylindrical body inserted into the through hole, and the tensioning step is performed. Rubber pullability evaluation method described in . The concave portion with a bottom is formed in the mold member, and the cylindrical body containing the unvulcanized rubber is inserted halfway into the concave portion with a bottom, and the pressing member presses the concave portion. The method for evaluating the pullability of rubber according to claim 1, wherein the unvulcanized rubber is heated while being pushed into the bottom of the bottomed recess. A cylindrical body, a pressure member inserted into the cylindrical body, a mold member having a recess, and the pressure member in which unvulcanized rubber housed in the cylindrical body is inserted into the cylindrical body, a heating mechanism that heats the specimen while being pushed into the recess to form a test piece of a small piece of vulcanized or semi-vulcanized rubber having a protrusion that is in close contact with the side surface of the recess without adhering; , a release layer interposed between the test specimen and the mold member in a region other than the side surface where the test specimen and the mold member face each other, and after forming the test specimen, the test specimen and the mold member are A tensioning mechanism that performs a tensioning step of moving at least one of the members in a direction away from each other, applying a tensile force to the test specimen, pulling out the protrusion from the recess, and peeling the test specimen from the mold member. Then, the measuring device and the cylindrical body, in which the unvulcanized rubber is accommodated on one opening side and the pressurizing member is inserted from the other opening side, are relatively moved from a predetermined preparation position to the recess, and one opening is opened. a conveyance mechanism for relatively moving the cylindrical body, in which the test specimen is accommodated on one side and the pressure member is inserted in the other opening side, from the recess to a predetermined storage position; The series of steps up to the completion of the tensioning process is set to be repeated using the same recess, and during the tensioning process for each of the many test specimens formed, the interface between the protrusion and the side surface is A device for evaluating pullability of rubber, characterized in that the breaking strength is measured by the measuring device.

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