JP4148130B2 - Specimen gripper for material testing machine - Google Patents

Description

  The present invention relates to a wedge-type test piece grip for a material testing machine.

  2. Description of the Related Art Conventionally, there is known a material testing machine that grips both upper and lower ends of a test piece with a pair of left and right gripping teeth members provided on a pair of upper and lower grippers and loads the test piece (for example, Patent Document 1).

Japanese Utility Model Publication No. Hei 4-38550

  In the material testing machine described above, a wedge-type gripping tool is used. In the conventional wedge-type gripping tool, an outer frame having a tapered surface for opening and closing the gripping teeth is provided, and due to the contact taper with the gripping teeth when the outer frame is moved relative to a pair of gripping teeth. The gripping teeth are closed to generate a gripping force.

  In this case, since the outer frame is relatively moved by the screw, the gripping force is proportional to the force for turning the screw. Further, since the gripping teeth are pulled by the test piece during the test, the contact taper acts in the direction of closing the gripping teeth, and the gripping force increases in proportion to the pulling force.

  When performing a tensile test of a micromaterial such as a small electronic component, the strength of the test material itself is low, and thus it is necessary to grip the test material with a gripping force that does not break the test material. However, as described above, when the gripping teeth are driven by the screw force, there is a drawback that the gripping force changes due to a subtle difference in the rotation angle applied to the screw. There is also a disadvantage that the gripping force changes due to the wedge effect due to the pulling force.

The invention of claim 1 is applied to a wedge-type test piece gripping tool for a material testing machine having a pair of gripping tooth members that can be opened and closed in a direction to be separated from each other, and gripping the test piece by the pair of gripping tooth members. A guide member having a pair of inclined surfaces which are inclined so as to be narrowed in a pulling direction by the gripping tool, and having a tapered surface on which the pair of gripping tooth members are slidably contacted, and the guide member to the pair of gripping tooth members by biasing force The urging means for moving the pair of gripping tooth members on the tapered surface in a direction approaching each other by relatively moving in the direction opposite to the pulling direction, and changing the magnitude of the urging force of the urging means. Move between the force adjusting means, a first position where the guide member is locked against the biasing force of the biasing means, and a second position where the guide member is driven by the biasing force after releasing the lock. Actuator Characterized in that it comprises.

  According to the present invention, the gripping force by the gripping tooth member can be made constant. Further, it is possible to prevent the occurrence of the gripping force due to the pulling force during the pulling test.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a material testing machine in which a specimen gripping tool for a material testing machine according to the present invention is used.

  The material testing machine 10 includes a base 11, a pair of left and right support columns 12 and 13 erected on the left and right ends of the base 11, an upper yoke 14 horizontally mounted on top of the pair of support columns 12 and 13, both ends The cross head 15 is attached to the support columns 12 and 13 so that the vertical position can be adjusted, and the hydraulic actuator 16 for load is provided.

  The load hydraulic actuator 16 is installed on the base 11. A lower grip 18 for gripping the lower end side of the test piece TP is attached to the piston rod 17 of the hydraulic actuator 16. A load cell 19 is attached to the crosshead 15, and an upper grip 20 that holds the upper end side of the test piece TP is attached to the load cell 19.

  In the testing machine shown in FIG. 1, the lower gripping tool 18 and the upper gripping tool 20 have the same structure. In the case where a tensile test for wire bonding of a semiconductor chip is performed, a test is performed by attaching a holder for fixing a substrate provided with a semiconductor chip on the piston rod 17 instead of the lower gripping tool 18. I have to. Hereinafter, the upper gripping tool 20 will be described.

  2 to 4 are views showing the gripping tool in detail, FIG. 2 is a front view, FIG. 3 is a side view, and FIG. 4 is a sectional view taken along line BB in FIG. Reference numeral 201 denotes a base of the gripping tool 20, and the base 201 is attached to a load cell 19 fixed to the crosshead 15. An actuator 202 for moving the outer frame 203 up and down is fixed to the base 201. A gripping tooth supporting member 205 having a T-shape in a front view for supporting the gripping teeth 204 is fixed to the lower end surface of the base 201.

  The actuator 202 is one in which a rod 202a is driven up and down. For example, an actuator that drives a ball screw with a stepping motor, an air cylinder, a hydraulic cylinder, or the like is used. A lifting tool 220 for lifting the outer frame 203 upward is attached to the tip of the rod 202a. The hanger 220 engages with a locking member 221 attached to the outer frame 203. The hanger 220 can be moved up and down by driving the actuator 202.

  A projecting portion 220 a that protrudes to the left and right is formed at the lower end portion of the hanger 220. On the other hand, the locking member 221 is formed with a pair of protruding walls 221a protruding forward, and each protruding wall 221a is formed with a notch 221b that opens downward. The hanger 220 is inserted into a gap formed between the protruding walls 221a, and each convex portion 220a of the hanger 220 is engaged with the notch 221b (see FIGS. 3 and 4).

  As shown in FIG. 3, a support member 208 that supports the linear motion guide 206 and the screw rod 207 is fixed to the back surface of the base 201. The screw rod 207 is vertically fixed to the horizontal portion of the support member 208 using a lock nut 209. The linear motion guide 206 extends in the vertical direction of the base 201, and a slider 210 is provided on the guide so as to be slidable in the vertical direction.

  An outer frame support member 211 that supports the outer frame 203 is fixed to the slider 210. In FIG. 3, the outer frame 203 is shown in cross section. The outer frame 203 is fixed to the lower end of the outer frame support member 211, and a spring receiving member 212 is horizontally attached to the upper end of the outer frame support member 211. The screw rod 207 described above is provided so as to penetrate the spring receiving member 212, and a compression spring 214 is disposed between the biasing force adjusting member 213 attached to the screw rod 207 and the spring receiving member 212. Yes.

As a result, the outer frame support member 211 and the outer frame 203 are urged downward by the spring force of the compression spring 214, and the slider 210 moves downward by the urging force. The urging force by the compression spring 214 can be changed by changing the vertical position of the urging force adjusting member 213. Reference numeral 215 denotes a screw for fixing the position of the biasing force adjusting member 213. In this embodiment, the compression spring 214 is used as a means for urging the outer frame 203 downward. However, as long as a constant urging force can be applied, the compression spring 214 is not limited to a spring, and an air cylinder, a hydraulic cylinder, a weight Etc.

  FIG. 5 is a view showing a pair of gripping teeth 204 housed in the outer frame 203. Each gripping tooth 204 is connected to the gripping tooth support member 205 by a connecting member 216. The connecting member 216 is formed of an elastic material such as a leaf spring. Each gripping tooth 204 has a claw 204b attached thereto, and the test piece is held between the claw 204b.

  A holding plate 219 for stably housing the gripping teeth 204 in the outer frame 203 is attached to the front side of the outer frame 203. FIG. 5 shows a state where the gripping teeth 204 are open, and the connecting member 216 is not deformed. When the gripping teeth 204 are closed from this state, the connecting member 216 is elastically deformed so as to bend in the central axis direction (see FIG. 6).

  An outer side surface of each gripping tooth 204 is an inclined surface 204a, and the pair of inclined surfaces 204a are inclined so as to intersect in the upper part of the figure. On the other hand, the surface 203a facing the inclined surface 204a of the outer frame 203 is also an inclined surface, and the tapered surface formed by the inclined surface 203a has the same shape as the tapered surface formed by the inclined surface 204a of the gripping teeth 204. Yes. That is, the tapered surfaces formed by the inclined surfaces 203a and 204a are narrower in the pulling direction (upward in the drawing) by the gripping teeth 204.

  Next, the opening / closing operation of the gripping tool 20 will be described with reference to FIG. The state shown in FIGS. 2 and 3 is a state where the gripping teeth 204 are opened. At this time, the convex part 220 a of the hanging tool 220 is engaged with the notch part 221 b of the protruding wall 221 a provided on the locking member 221. Further, the outer frame 203 biased downward by the compression spring 214 is locked by the actuator 202. FIG. 6 shows the relationship between the outer frame 203 and the gripping teeth 204 and how the gripping teeth 204 are opened.

  When the actuator 202 is driven from this state to lower the hanger 220, the outer frame 203 moves downward by the urging force of the compression spring 214. Each of the inclined surfaces 203a of the outer frame 203 and the inclined surfaces 204a of the gripping teeth 204 are tapered surfaces that are narrowed upward. Therefore, when the outer frame 203 moves relative to the gripping teeth 204 as indicated by a two-dot chain line, the inclined surface 204a moves relative to the inclined surface 203a. As a result, the left and right gripping teeth 204 move in the left-right direction as indicated by arrows R1 and R2 and close. At this time, the connecting member 216 is elastically deformed so as to be bent in the central axis direction.

  On the contrary, when the gripping teeth 204 are opened from the closed state, the lifting device 220 is driven upward by the actuator 202. Then, the outer frame 203 moves upward against the urging force of the compression spring 214. Each gripping tooth 204 moves to the outside while maintaining contact with the outer frame 203 by the elastic force when the connecting member 216 returns to its original state. As a result, the gripping teeth 204 are opened.

  FIG. 7 shows an example of a conventional gripping tool, and is a cross-sectional view of the gripping tool as viewed from the front. A handle 71 is attached to the outer frame 70 with a screw structure, and a connecting shaft 72 is attached to the handle 71 through its center. A pair of gripping teeth 73 are attached to the lower end portion of the connecting shaft 72 so as to be movable left and right. The gripping teeth 73 and the outer frame 70 are in taper contact with each other, but the tapered surface is composed of an inclined surface that expands with respect to the pulling direction of the gripping teeth 73 (upward in the figure) contrary to the present embodiment. Yes.

  When the handle 71 is rotated in one direction, the connecting shaft 72 is lowered and the gripping teeth 73 are closed. When the handle 71 is rotated in the other direction, the connecting shaft 72 is lifted and the gripping teeth 73 are opened. For this reason, the gripping force by the gripping teeth 73 depends on the rotational force of the handle 71, and the gripping force varies from work to work, and the test piece may not be gripped with the optimal gripping force.

The gripping tool 20 of the present embodiment described above has the following characteristics.
(1) Since the outer frame 203 is biased downward with a substantially constant force by the compression spring 214, the gripping force by the gripping teeth 204 becomes a value proportional to the spring force of the compression spring 214. Therefore, the test piece is gripped with a constant force. Even a test object with a low strength such as a small electronic component does not break the test object itself.

  (2) During the tensile test, the test piece is pulled upward in the figure by the gripping teeth 204, but conversely, the gripping teeth 204 are pulled in the downward direction in the figure by the test piece. Since the conventional gripping tool shown in FIG. 7 has a tapered surface opposite to that of the present embodiment, the gripping tooth is pulled downward in the drawing during the tensile test, so that the gripping force proportional to the pulling force is obtained. It occurs due to the wedge effect. However, in this embodiment, since the contact taper surface has a tapered shape opposite to the conventional one, even if the gripping teeth 204 are pulled downward, the outer frame 203 follows by the urging force, and the gripping teeth 204 The relative positional relationship with the outer frame 203 does not change. As a result, the wedge effect is not generated, and the generation of a gripping force proportional to the pulling force can be prevented.

  Note that the vertical positional relationship between the gripping teeth 204 and the outer frame 203 is preferably set as shown in FIG. That is, when the gripping teeth 204 are in the closed state, the lower surface of the gripping teeth 204 and the lower surface of the outer frame 203 indicated by a two-dot chain line are set on the same plane. When the test piece TP is gripped by the gripping teeth 204, the point PP which is the lower end of the inclined surface 203a becomes the force point of the gripping force, and the point PA which is the lower end of the contact surface of the claw 204b provided on the gripping teeth 204 is the action point. Become. When the test piece TP is a small electronic component or the like, since the thickness of the test piece is thin, the vertical deviation Δz between the points PP and PA can be very small.

  By the way, when the nail | claw 204b protrudes rather than the lower surface of the grasping tooth | gear 204 as shown in FIG. 5, point PA becomes a lower surface position of the nail | claw 204b. However, in the present invention, the claw 204b is considered as a component of the gripping teeth 204, and the lower surface position of the claw 204b is regarded as the lower surface position of the gripping teeth.

  As a result, the moment generated by the deviation Δz can be suppressed to a very small level, and the gripping state can be prevented from becoming unstable due to the gripping teeth 204 being inclined. Ideally, when the test piece PT is gripped, it is best that the points PP and PA are on the same plane (Δz = 0), so that only a specimen having a certain thickness is inspected. For example, the lower surface of the gripping teeth 204 and the lower surface of the outer frame 203 when the sample is held may be set on the same plane.

"Modification"
FIG. 9 is a diagram showing a modification of the above-described embodiment. In the above-described embodiment, the outer frame 203 is moved up and down using the compression spring 214 and the actuator 202. However, in the gripping tool 20A shown in FIG. The outer frame 203 is attached to the tip portion of the rod 230 a of the air cylinder 230. FIG. 9 schematically shows the structure of the air cylinder 230. The relationship between the outer frame 203 and the gripping teeth 204 is the same as that of the gripping tool 20 described above.

  The outer frame 203 can be moved up and down by driving the rod 230a of the air cylinder 230 up and down. A piston 231 is connected to the rod 230a, and cylinder chambers 232 and 233 into which pressurized air is introduced are provided above and below the piston 231. Then, compressed air having different pressures is introduced into the cylinder chambers 232 and 233, and the piston 231 is moved up and down by the pressure difference between the upper and lower sides.

  For example, if the pressure P1 in the cylinder chamber 232 is set larger than the pressure P2 in the cylinder chamber 233, the piston 231 descends and the outer frame 203 connected to the rod 230a has a force proportional to the differential pressure ΔP (= P1-P2). Is pushed downward. On the other hand, if P1 <P2, the piston 231 moves up and the outer frame 203 is urged upward. Since the outer frame 203 is urged downward with a constant force in this way, the test piece can be gripped with a constant gripping force as in the above-described embodiment.

  In the above-described embodiment, the connecting member 216 is configured by an elastic member such as a leaf spring. However, the connecting member 216 may be configured to be capable of parallel movement using a parallel link mechanism or the like. The present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  In the correspondence between the embodiment described above and the elements of the claims, the outer frame 203 constitutes a guide member, and the compression spring 214 constitutes an urging means.

It is a figure which shows one Embodiment of the material testing machine in which the test piece gripping tool for material testing machines by this invention was used. 3 is a front view of the gripping tool 20. FIG. 3 is a side view of the gripping tool 20. FIG. It is BB sectional drawing of FIG. It is a figure which shows the outer frame 203 and the grasping tooth | gear 204. FIG. It is a figure explaining the opening / closing operation | movement of the holding tool. It is a figure which shows the conventional holding tool. It is a figure explaining the up-and-down positional relationship of the grasping tooth | gear 204 and the outer frame 203. FIG. It is a figure which shows the modification of a holding tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Material testing machine 18,20,20A Grasp 201 Base 202 Actuator 202a, 230a Rod 70, 203 Outer frame 203a, 204a Inclined surface 73,204 Grasp tooth 205 Grasp tooth support member 206 Linear motion guide 207 Screw rod 208 Support member 210 Slider 211 Outer frame support member 212 Spring receiving member 213 Energizing force adjustment member 214 Compression spring 216 Connecting member 220 Lifting tool 220a Protruding part 221 Locking member 221a Protruding wall 221b Notch 230 Air cylinder TP Test piece

Claims (1)

In a test piece gripping tool for a wedge-type material testing machine having a pair of gripping tooth members that can be opened and closed in a direction to be separated from each other, and gripping a test piece by the pair of gripping tooth members,
A guide member comprising a pair of inclined surfaces that are inclined so as to be narrowed in a pulling direction by the gripping tool and having a tapered surface on which the pair of gripping tooth members are slidably contacted,
The guide member is moved relative to the pair of gripping tooth members by a biasing force in a direction opposite to the pulling direction, and the pair of gripping tooth members on the tapered surface are slid in a direction approaching each other. Means,
A biasing force adjusting means for changing the magnitude of the biasing force of the biasing means;
It moves between a first position where the guide member is locked against the biasing force of the biasing means and a second position where the locking member is released and the guide member is driven by the biasing force. And a test piece gripping tool for a material testing machine.

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