JP5711983B2 - Grasping tool for tensile test - Google Patents

Description

  The present invention relates to a tensile test grip, and more particularly to a tensile test grip that can prevent chucking of a test piece made of synthetic resin with a simple device and operation.

  Conventionally, a tensile test of a synthetic resin material is performed by holding both ends of a test piece with a pair of grips and applying a tensile force to the test pieces between the grips along a load axis by a tensile tester. . If the gripping force of the gripping tool is small, the test piece comes out of the gripping tool when a tensile force is applied. In order to prevent this, if the gripping force of the gripping tool is increased, the test piece may be locally deformed near the gripping tool and may be broken there (hereinafter referred to as “chuck break”). Since the breaking load due to the chuck break is smaller than the original breaking load of the synthetic resin material, there is a problem that an accurate test result cannot be obtained if the chuck break occurs.

  It is known that a similar phenomenon occurs in a tensile test of a metal material. In order to prevent this, in the tensile test equipment for metal materials, the cooling means for cooling the chuck holding both ends of the test piece to a temperature below room temperature, and the temperature control for controlling the surface temperature of the central part of the test piece to the specified temperature. What is provided with a means is disclosed (patent document 1). In the technique disclosed in Patent Document 1, both ends of the test piece are cooled to a temperature below room temperature, and the surface temperature of the central portion of the test piece is controlled to a specified temperature. As a result, the tensile strength at the end of the test piece can be made larger than the tensile strength at the central portion, and chuck breakage can be prevented.

Japanese Patent Laid-Open No. 5-249011

  However, the technique disclosed in Patent Document 1 relates to a tensile test of a metal material, and there is no technique for preventing a chuck break with respect to a tensile test of a synthetic resin material.

  Further, when the technique disclosed in Patent Document 1 is applied to a tensile test of a synthetic resin material, the tensile tester includes a cooling device connected to a cooling coil provided in the chuck, and a central portion of the test piece. And a temperature sensor for detecting the surface temperature of the central portion of the test piece, and a temperature control device connected to the cooling device, the heating coil and the temperature sensor. Since control is performed so that a temperature gradient is formed between the surface temperature of the central portion and the end portion, there has been a problem that the configuration and operation of the apparatus are complicated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a tensile test gripping tool that can prevent a test piece made of synthetic resin from being broken by a simple device and operation.

Means for Solving the Problems and Effects of the Invention

  In order to achieve this object, according to the grip for a tensile test according to claim 1, the fastener is formed from the grip body by means of a fastener that is detachably formed on the grip body connected to the tensile tester. It is cooled in the removed state. After the cooled fastener is attached to the gripper body, when the end of the test piece is gripped by the chuck by the fastening operation of the fastener, the end of the test piece is caused by heat conduction between the test piece and the chuck and the fastener. And the chuck is cooled. As a result of the specimen and chuck being cooled, the fastener is warmed. The temperature of the fastener or chuck is indicated by an indicator, and it can be estimated from the temperature whether the end of the test piece has been cooled. Since the test piece made of synthetic resin increases in hardness when cooled, it is possible to prevent local deformation in the vicinity of the end portion of the test piece by performing a tensile test after the end portion of the test piece is cooled. This can prevent chuck breakage.

  As described above, according to the tensile test grip according to the first aspect, it is possible to prevent the test piece made of synthetic resin from being broken by a simple device and operation without using a complicated device and operation as in the prior art. effective.

  Furthermore, since the test piece is cooled using a fastener that is used to open and close the chuck, it is easy to attach and detach, and the operability can be improved.

  According to the tensile test gripping tool of the second aspect, the chuck formed detachably on the gripping tool main body connected to the tensile tester is cooled in a state where it is detached from the gripping tool main body. After the cooled chuck is attached to the gripper body, when the end of the test piece is gripped by the chuck, the end of the test piece is cooled by heat conduction between the test piece and the chuck. At the same time, heat conduction occurs between the grip body and the chuck, and the grip body is cooled. The temperature of the gripper main body or chuck is indicated by an indicator, and it can be estimated from the temperature whether the end of the test piece has been cooled. Since the test piece made of synthetic resin increases in hardness when cooled, it is possible to prevent local deformation in the vicinity of the end portion of the test piece by performing a tensile test after the end portion of the test piece is cooled. This can prevent chuck breakage.

  According to the grip for a tensile test according to claim 3, since the appearance of the indicator portion changes when it reaches a set temperature 5 to 10 ° C. lower than room temperature, the temperature of the member on which the indicator portion is formed is 5 ° C. from room temperature. It can be detected that a temperature lower by 10 ° C. has been reached. Since the temperature of the member on which the indicator portion is formed changes as a result of the test piece being cooled, when the appearance of the indicator portion changes, it is estimated that the end of the test piece has been cooled to a temperature lower than room temperature. Is done. When the edge of the test piece made of synthetic resin is at a temperature lower than room temperature, a temperature gradient is created between the end and the center of the test piece, and the end of the test piece is harder than the center. be able to. Thereby, in addition to the effect of Claim 1 or 2, there exists an effect which can prevent chuck | zipper breakage reliably.

  According to the grip for tensile test according to claim 4, the indicator portion includes a recess formed in the fastener or the chuck, and a liquid material having a melting point 5 to 10 ° C. lower than room temperature accommodated in the recess. Therefore, it can be detected that the temperature of the fastener or chuck has risen to 5 to 10 ° C. lower than room temperature by melting the solidified liquid material. Since the fastener or the chuck is warmed as a result of the test piece being cooled, it is presumed that the end of the test piece was cooled to a temperature lower than room temperature when the liquid material melted. When the edge of the test piece made of synthetic resin is at a temperature lower than room temperature, a temperature gradient is created between the end and the center of the test piece, and the end of the test piece is harder than the center. be able to. Thereby, in addition to the effect of Claim 1 or 2, there exists an effect which can prevent chuck | zipper breakage reliably.

  According to the grip for tensile test according to claim 5, the test piece has the same cross-sectional area in the direction perpendicular to the direction of the tensile force formed in the direction of the tensile force. It is possible to omit preparation of a test piece that is processed to have a wider cross-sectional area at the end than the cross-sectional area at the center. Accordingly, in addition to the effect of any one of claims 1 to 4, there is an effect that the preparation work of the test piece can be simplified.

(A) is a front view of the grip for tensile test in 1st Embodiment, (b) is a side view of the grip for tensile test. (A) is a side view of the fastener of the tensile test gripping tool, and (b) is a perspective view of the chuck of the tensile test gripping tool in the second embodiment. (A) is a front view of the grip for tensile test in 3rd Embodiment, (b) is a perspective view of the chuck | zipper of the grip for tensile test.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. First, with reference to FIG.1 and FIG.2 (a), the grip 1 for tension tests in 1st Embodiment of this invention is demonstrated. FIG. 1A is a front view of the tensile test grip 1 according to the first embodiment, and FIG. 1B is a side view of the tensile test grip 1.

  As shown in FIGS. 1 (a) and 1 (b), the tensile test grip 1 is a pair of members connected to a load rod 100 of a tensile tester. In order to apply a tensile force to the test piece T along L, it is a member that holds the end of the test piece T made of synthetic resin. The tension test gripping tool 1 is disposed so as to face the chuck 3, a grip body 2 connected via a universal joint 101, a chuck 3 formed on the end of the gripping tool body 2, and the chuck 3. The chuck 4 formed separately from the grip body 2 and the chucks 3 and 4 are attached to the grip body 2 so that the chucks 3 and 4 can be opened and closed, and the fastener 10 is formed to be detachable from the grip body 2 ( A bolt 11 and a nut 12).

  The gripper main body 2 and the chuck 4 are formed by a rectangular plate-like body when viewed from the front, and mounting holes 3b and 4b that are formed to penetrate in the thickness direction are formed at relative positions on both sides of the load shaft L, respectively. Has been. The attachment holes 3b and 4b are portions through which the shaft portion 11a of the bolt 11 is inserted, and the nut 12 is fastened to the shaft portion 11a. By inserting the test piece T between the chucks 3 and 4 coaxially with the load shaft L and fastening the bolt 11 and the nut 12, the test piece T is held against the gripping surfaces 3a and 4a of the chucks 3 and 4, and the test is performed. The end of the piece T is gripped by the chucks 3 and 4.

  Next, the fastener 10 of the tensile test grip 1 will be described with reference to FIG. FIG. 2A is a side view of the fastener 10 (bolt 11) of the tensile test grip 1. FIG. In FIG. 2A, the longitudinal direction of the shaft portion 11a of the bolt 11 is not shown.

  The bolt 11 has a bottomed concave portion 11c that is formed from the head portion 11b toward the shaft portion 11a on the distal end surface of the head portion 11b. The concave portion 11c is a part of an index portion indicating the temperature of the bolt 11, and accommodates a liquid material 11d having a melting point that is 5 to 10 ° C. lower than the room temperature of a test chamber (not shown) in which a tensile tester is installed. It is a part. In order to prevent the melted liquid material 11d from leaking out from the concave portion 11c, a transparent film 11e that can visually recognize the inside of the concave portion 11c is stuck to the distal end surface of the head portion 11b while sealing the concave portion 11c. In the present embodiment, acetic acid (melting point is about 17 ° C.) is used as the liquid 11d.

  Next, a method of using the tensile test grip 1 will be described. It is assumed that the room temperature of the test room where the tensile tester is installed is set to about 22 to 27 ° C. After removing the bolt 11 and the nut 12 from the grip body 2 connected to the load rod 100 of the tensile tester, the bolt 11 and the nut 12 are stored in a freezer (not shown) and left for a sufficient time. As a result, the bolt 11 and the nut 12 are cooled, and the liquid material 11d accommodated in the recess 11c of the bolt 11 is cooled below the melting point and solidifies.

  In the present embodiment, the test piece T is obtained by cutting a synthetic resin tube slightly longer than the distance between the pair of tensile test grips 1 and 1. Thus, the tensile test is performed using the test piece T in which the cross-sectional area perpendicular to the direction of the tensile force (the direction of the load axis L) is the same over the direction of the tensile force (the direction of the load axis L). be able to.

  When performing a tensile test of the test piece T, the sufficiently cooled bolt 11 and nut 12 are taken out from a freezer (not shown) and immediately inserted between the chucks 3 and 4 coaxially with the load shaft L. At the same time, the nut 12 is fastened while the bolt 11 is inserted through the mounting holes 3b and 4b. As a result, the test piece T is held against the gripping surfaces 3 a and 4 a of the chucks 3 and 4, and the end of the test piece T is gripped by the tensile test grip 1.

  In this state, the chucks 3 and 4 are cooled by heat conduction between the chucks 3 and 4 and the bolts 11 and nuts 12, and then the end of the test piece T held by the chucks 3 and 4 is cooled. As a result of the test piece T being cooled, the bolt 11 and the nut 12 are warmed. It is indicated that the temperature of the bolt 11 rose to about 17 ° C. (melting point of acetic acid) by melting the liquid material 11d as the indicator part. The bolt 11 and the nut 12 are also heated by radiation and the like, but are heated, but the heat conduction between the chucks 3 and 4 and the test piece T and the bolt 11 and the nut 12 is dominant, so Or melting), it can be estimated whether the end of the test piece T has been cooled. Since the test piece T made of synthetic resin increases in hardness when cooled, it is confirmed that local deformation occurs near the end of the test piece T by performing a tensile test after the end of the test piece T is cooled. Can be prevented. Thereby, the test piece T can be prevented from being broken.

  Here, when the test piece T is made of metal, the thermal conductivity is large, and therefore, when the end of the test piece T is cooled, a temperature gradient is hardly generated in the longitudinal direction of the test piece T. Therefore, when the end portion of the test piece T is cooled, the central portion in the longitudinal direction of the test piece T is also cooled in a short time. As a result, when the tensile test grip 1 according to the present embodiment is used, a test result representing the original material characteristics of the test piece T cannot be obtained. Therefore, in order to forcibly generate a temperature gradient in the longitudinal direction of the metal test piece T, a complicated apparatus and a complicated operation as disclosed in Patent Document 1 are necessary.

  On the other hand, since the test piece T made of synthetic resin in the present embodiment has a smaller thermal conductivity than that of the metal material, the longitudinal direction of the test piece T can be obtained by causing the chucks 3 and 4 to hold the test piece T. A large temperature gradient can be generated. Therefore, even if the end portion of the test piece T is cooled, the central portion in the longitudinal direction of the test piece T is hardly cooled. As a result, the central portion in the longitudinal direction of the test piece T is maintained at substantially room temperature, and a test result representing the original material characteristics of the test piece T can be obtained.

  As described above, according to the tensile test grip 1 in the first embodiment, the chuck of the test piece T made of a synthetic resin can be obtained by a simple device and operation without using a complicated device and operation as in the prior art. Cutting can be prevented and accurate test results can be obtained.

  Further, by using the fastener 10 (bolt 11) which is removed from the gripper main body 2 and cooled, the chucks 3 and 4 are closed and the test piece T is gripped, whereby the test piece T is cooled via the chucks 3 and 4. be able to. Thereby, the test piece T can be gradually cooled via the chucks 3 and 4, and the test piece T can be prevented from being rapidly cooled. Moreover, since the fastener 10 that can be easily detached from the gripper main body 2 is used, the detachability operability can be improved.

  Further, since the fastener 10 is in surface contact with the gripper main body 2 and the chuck 4, the heat conduction efficiency can be improved. Furthermore, the same number of fasteners 10 as the number of test pieces T to be subjected to the tensile test are cooled, and each time the test pieces T are replaced, the fasteners 10 are replaced with cooled ones, thereby reproducing the test results. Can be secured.

  Moreover, the indicator part which shows the temperature of the fastener 10 is melting | fusing point lower 5-10 degreeC than the recessed part 11c formed in the fastener 10 (bolt 11), and the room temperature (about 22-27 degreeC) accommodated in the recessed part 11c. Since the liquid material 11d (acetic acid) having (approximately 17 ° C.) is configured, the fastener 10 is below the melting point by confirming whether the liquid material 11d is in a solidified state or a melted state. It can be confirmed whether or not it is cooled.

  Moreover, after attaching the cooled fastening part 10 to the holding tool main body 2, the temperature of the fastening tool 10 rose to 5-10 degreeC temperature lower than room temperature by confirming melting | dissolving of the solidified liquid substance 11d. Can be detected. Since the fastener 10 is warmed as a result of the cooling of the test piece T, when the liquid 11d is melted, it is estimated that the end of the test piece T has been cooled to a temperature 5 to 10 ° C. lower than the room temperature. The The test piece T made of synthetic resin has a temperature gradient between the end portion and the central portion of the test piece T when the end portion held by the chucks 3 and 4 is at a temperature 5 to 10 ° C. lower than room temperature, The end of the test piece T can be harder than the center. This reliably prevents the test piece T from being broken. In addition, when the tensile test was performed when the chucks 3 and 4 were at a temperature 5 to 10 ° C. lower than room temperature, it was confirmed by experiments that the chuck of the test piece T could be prevented and an accurate test result could be obtained. .

  In the present embodiment, the end of the test piece T is hardened by cooling, and local deformation near the end of the test piece T can be prevented. Omitting preparation to be set wider than the cross-sectional area of the central portion, the cross-sectional area perpendicular to the direction of the tensile force (the direction of the load axis L) is the same over the direction of the tensile force The formed test piece T can be used. Thereby, not the tensile test result of the test piece cut out from the product or the sample but the tensile test result of the product or the sample itself can be obtained.

  Next, a second embodiment will be described with reference to FIG. 1st Embodiment demonstrated the case where the recessed part 11c in which the liquid substance 11d was accommodated in the fastener 10 (bolt 11) was formed. On the other hand, in the second embodiment, a case will be described in which the recess 14b in which the liquid material 14c is accommodated is formed in the chuck 14. FIG. 2B is a perspective view of the chuck 14 of the tensile test gripping tool according to the second embodiment. The chuck 14 is disposed in place of the chuck 4 of the tensile test grip 1 in the first embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and the following description will be given. Is omitted.

  The chuck 14 is a member formed by a rectangular plate-like body in plan view, and is a surface through which the two attachment holes 4b are formed, and has a bottomed recess 14b on the opposite surface 14a of the gripping surface 4a. Is formed. The concave portion 14b is a part of the index portion and is a portion in which the liquid material 14c is accommodated. In this Embodiment, the wax adjusted to 5-10 degreeC melting | fusing point lower than the room temperature of the test room in which the tensile tester is installed is accommodated as the liquid substance 14c.

  Next, a method of using the tensile test gripping tool in the second embodiment will be described. After removing the chuck 14 by removing the bolt 11 and the nut 12 from the grip body 2 connected to the load rod 100 (see FIG. 1) of the tensile tester, the chuck 14 is placed in a freezer (not shown) Leave it for a long time. As a result, the chuck 14 is cooled, and the liquid material 14c accommodated in the recess 14b of the chuck 14 is cooled below the melting point and solidifies.

  When performing a tensile test, the cooled chuck 14 is taken out from a freezer (not shown), and immediately after inserting the test piece T between the chucks 3 (see FIG. 1) and 14 coaxially with the load shaft L, the bolt 11 And the nut 12 is fastened. As a result, the test piece T is held against the gripping surfaces 3 a and 4 a of the chucks 3 and 14, and the end of the test piece T is gripped by the chucks 3 and 14. As a result, the end of the test piece T held by the chucks 3 and 14, the bolt 11, and the like are cooled. As a result of cooling the test piece T, the bolt 11 and the like, the chuck 14 is warmed. It is indicated that the temperature of the chuck 14 has risen to the melting point of the liquid material 14c by melting the liquid material 14c serving as the indicator. Although the chuck 14 is also warmed by radiation or the like, since heat conduction between the test piece T and the chuck 14 is dominant, it can be estimated from the state of the liquid 14c whether the end of the test piece T has been cooled. Since the test piece T made of synthetic resin increases in hardness when cooled, it is confirmed that local deformation occurs near the end of the test piece T by performing a tensile test after the end of the test piece T is cooled. Can be prevented. This can prevent chuck breakage.

  As described above, also in the second embodiment, as in the first embodiment, the test piece T made of a synthetic resin can be obtained by a simple device and operation without using complicated devices and operations as in the prior art. Chuck breakage can be prevented. Further, since the test piece T is cooled by being held by the cooled chuck 14, the cooling efficiency of the test piece T can be improved. In addition, as many chucks T as the number of test pieces T to be subjected to the tensile test are cooled, and each time the test pieces T are replaced, the chuck 14 is replaced with a cooled one, thereby improving the reproducibility of the test results. It can be secured.

  Next, a third embodiment will be described with reference to FIG. In 1st Embodiment and 2nd Embodiment, the recessed part 11c, 14b in which the liquid materials 11d and 14c are accommodated in the fastener 10 or the chuck | zipper 14 was formed, and the case where they comprised an indicator | index part was demonstrated. On the other hand, in 3rd Embodiment, the case where the label-shaped temperature indicator 23d is affixed on the chuck | zipper 23 as a parameter | index part is demonstrated. In addition, the same part as 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits the following description. FIG. 3A is a front view of the tensile test grip 21 in the third embodiment, and FIG. 3B is a perspective view of the chuck 23 of the tensile test grip 21. 3A, one of the pair of tensile test grips 21 connected to the load rod 100 is not shown.

  As shown in FIG. 3A, the tensile test grip 21 is connected to the load rod 100 of the tensile tester through the universal joint 101 and is formed in a substantially U-shape when viewed from the front. A tool body 22 and a pair of chucks 23, 23 disposed inside the grip tool body 22 are configured. In the gripping tool main body 22, mounting holes 22 b are formed through the opposing portions 22 a on both sides formed in a substantially U shape, and a screw rod 24 as a fastener is screwed into the mounting hole 22 b. The screw rod 24 has a knob portion 24 a at one end, and the other end is in contact with the chuck 23.

  As shown in FIGS. 3A and 3B, the chuck 23 is a member formed in a block shape, and the gripping surface 23a for gripping the test piece T is the surface on which the screw rod 24 comes into contact. It is formed on the opposite surface. Further, the chuck 23 is formed with an engagement hole 23c that is engaged with the other end of the screw rod 24 on the opposite surface 23b of the gripping surface 23a, and is visible in a state in which the chuck 23 is disposed in the gripping tool body 22. A label-shaped temperature indicator 23d as an indicator is affixed to.

  The temperature indicator 23d is a member that displays the fact that the preset temperature has been reached by a change in color tone, color, etc., using the property that the properties of wax, liquid crystal, microcapsule, etc. change depending on the temperature, For example, it is known from Japanese Patent No. 3426546. In the present embodiment, a temperature indicator 23d is used whose appearance (color) changes when it reaches a temperature 5 to 10 ° C. lower than the room temperature of the test room where the tensile tester is installed.

  Next, a method of using the tensile test grip 21 will be described. First, by rotating the knob 24a, the screw rod 24 is screwed out of the gripper main body 22 connected to the load rod 100 of the tensile tester, the screw rod 24 is removed from the engagement hole 23c of the chuck 23, and the chuck 23 is removed. Next, the chuck 23 is placed in a freezer (not shown) and left for a sufficient time. As a result, the chuck 23 is cooled, and the temperature display 23d is cooled below the set temperature, and the appearance (color) changes.

  When the tensile test is performed, the sufficiently cooled chuck 23 is taken out from a freezer (not shown) and is positioned inside the facing portion 22a of the gripping tool main body 22. Next, the test piece T is inserted coaxially with the load shaft L between the chucks 23, 23 while engaging the tip of the screw rod 24 in the engagement hole 23 c and rotating the screw rod 24. As a result, the test piece T is held against the gripping surfaces 23 a and 23 a of the chucks 23 and 23, and the end of the test piece T is gripped by the chucks 23 and 23. As a result, the end portion of the test piece T held by the chuck 23 and the screw rod 24 are cooled. As a result of cooling the test piece T and the screw rod 24, the chuck 23 is warmed. The change (discoloration) in the appearance of the temperature indicator 23d indicates that the chuck 23 has been raised to the set temperature. Although the chuck 23 is also warmed by radiation or the like, since the heat conduction between the test piece T and the chuck 23 is dominant, it can be estimated from the state of the temperature indicator 23d whether the end of the test piece T has been cooled. Since the test piece T made of synthetic resin increases in hardness when cooled, it is confirmed that local deformation occurs near the end of the test piece T by performing a tensile test after the end of the test piece T is cooled. Can be prevented. This can prevent chuck breakage.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed. For example, the numerical values (for example, the quantity of each component) given in the above embodiment are examples, and other numerical values can naturally be adopted.

  In the above-described embodiment, the test piece T formed in a tubular shape has been described. However, the test piece T is not necessarily limited thereto, and the test piece T may have other forms. Other forms are, for example, rod-like, thread-like, string-like, film-like, etc., and the cross-sectional area perpendicular to the direction of the tensile force (the direction of the load axis L) is the same over the direction of the tensile force. The synthetic resin material formed can be mentioned. As a result, it is possible to omit preparation of a test piece (as defined in JIS K6815-1: 2002) in which the cross-sectional area of the end portion is set wider than the cross-sectional area of the central portion, thereby simplifying the preparation work of the test piece. Can be Of course, it is also possible to perform a tensile test using a test piece processed into the shape specified in the above JIS K6815-1: 2002.

  In the first embodiment, the case where the index portion (recess 11c and liquid material 11d) is formed on the bolt 11 has been described. However, the present invention is not necessarily limited to this, and the index portion is formed on the nut 12. Is also possible. In this case, the same effect can be realized.

  Moreover, although the said 1st Embodiment demonstrated the case where the volt | bolt 11 and the nut 12 (fastener 10) were cooled, it is not necessarily restricted to this, The chuck | zipper 4 removed from the gripper main body 2 is also cooled together. Is possible. Thereby, the cooling efficiency of the test piece T can be improved.

  Further, in the first embodiment, the two nuts 12 are not removed and the two bolts 11 are not removed from the chuck 4, but one nut 12 is removed and the one bolt 11 is removed. Is also possible. Thereby, the attaching / detaching operation of the bolt 11 and the nut 12 can be simplified. Further, by cooling one bolt 11, the cooling rate and temperature of the test piece T when the bolt 11 is attached can be adjusted.

  In the third embodiment, the case where the temperature indicator 23d (indicator part) is attached to the chuck 23 to be cooled has been described. However, the present invention is not limited to this, and the temperature indicator 23d is attached to the chuck 23. Instead of this, it is also possible to affix a temperature display tool 23 d to the gripping tool body 22. In this case, the screw rod 24 and the gripping tool main body 22 are cooled by heat conduction by the chuck 23. Therefore, by confirming the temperature of the gripping tool main body 22 with the temperature display tool 23d, the test piece T is cooled. Can be estimated.

  In the third embodiment, the case where the chuck 23 is removed from the grip body 22 and cooled is described. However, the present invention is not limited to this, and the screw rod 24 is detached from the grip body 22 and the screw rod 24 is removed. It is also possible to cool. In this case, since the chuck 23 is cooled by heat conduction by the cooled screw rod 24, it can be estimated that the test piece T has been cooled by checking the temperature of the chuck 23 with the temperature display 23d. Since the chuck 23 is in contact with the test piece T, it is possible to improve the estimation accuracy that the test piece T has been cooled.

  In each of the above embodiments, the case where the fastener 10 and the chucks 14 and 23 are cooled by the freezer has been described. However, the present invention is not necessarily limited to this, and these are cooled using a refrigerant such as liquid nitrogen (deep cooling). It is also possible to Thereby, the time required for these cooling can be shortened. As a result, many tensile tests can be performed by cooling the fasteners 10 and the like for each tensile test without preparing the same number of fasteners 10 and the like as the number of test pieces T to be subjected to the tensile test. Become.

  In the first embodiment, the case where the recess 11c formed in the bolt 11 is sealed with the film 11e has been described. However, the present invention is not limited to this, and the recess 11c is opened without attaching the film 11e. It is also possible to leave it in the state. In this case, every time the bolt 11 is cooled, or after the bolt 11 is cooled, the liquid material 11d is solidified by pouring the liquid material 11d into the recess 11c, and the same effect can be realized.

  In each of the above-described embodiments, the case where acetic acid or wax is used as the liquid substances 11d and 14c constituting the indicator portion has been described. Of course it is also possible.

1,21 Grasping tool for tensile test 2,22 Grasping tool body 3,4,23 Chuck 10 Fastening tool 11c, 14b Recessed part (part of index part)
11d, 14c Liquid (part of the indicator)
23d Temperature indicator (index part)
24 Screw rod (fastener)
100 Load rod (part of tensile testing machine)
T specimen

Claims (5)

In a tensile test gripping tool that grips the end of a synthetic resin test piece,
A grip body connected to a tensile testing machine;
A chuck that is disposed on the gripper body and grips an end of the test piece;
A fastener that is configured to be openable and closable with the chuck, and is detachably formed on the gripper body, and is cooled in a detached state;
A tension test gripping tool, comprising: an index portion that is formed on the fastener or the chuck and is attached to the gripping tool main body and that indicates the temperature of the fastener or the chuck. In a tensile test gripping tool that grips the end of a synthetic resin test piece,
A grip body connected to a tensile testing machine;
A chuck that is detachably formed on the grip body, is cooled in a detached state, and grips an end of the test piece;
A tensile test gripping tool, comprising: an index portion formed on the chuck or the gripping tool main body and indicating the temperature of the chuck or the gripping tool main body attached to the gripping tool main body.   The tensile test grip according to claim 1 or 2, wherein the indicator portion changes in appearance when it reaches a set temperature 5 to 10 ° C lower than room temperature.   The said indicator part is provided with the recessed part formed in the said fastener or the said chuck | zipper, and the liquid substance which has melting | fusing point 5-10 degreeC lower than the room temperature accommodated in the said recessed part or, 2. A tensile test grip according to 2.   The tensile test according to any one of claims 1 to 4, wherein the test piece is formed so that a cross-sectional area in a direction orthogonal to a direction of the tensile force is the same over the direction of the tensile force. Gripping tool.