JP3161127U - Differential material testing machine - Google Patents

Abstract

A differential material capable of preventing local wear due to insufficient lubrication in an elevating screw part in a device for performing fatigue / durability tests with a slight displacement so that a slight displacement can be obtained by a difference in elevating speed of a crosshead. Providing a testing machine. SOLUTION: A crosshead 8 provided on a pair of screw rods 6a, 6b erected on a base 2 is provided on another pair of screw rods 3a, 3b erected on the same base. The test material TP is installed in the space between the cross heads 5 and the two pairs of screw rods are rotated by different rotary drive devices 11 and 12, respectively. The load is applied. This configuration eliminates the conventional reciprocation of the screw rod and nut in a very small region, prevents local wear and breakage by supplying a sufficient amount of lubricating liquid, and shortens the setup change time by high-speed movement of the crosshead. [Selection] Figure 1

Description

  The present invention relates to a material testing machine that applies a load to a test material by raising and lowering a crosshead by rotating a screw rod.

  Conventionally, as a method for applying, for example, a tensile load to a test material in order to examine the mechanical characteristics of the material, a cross head in which a pair of left and right screw rods are erected on a fixed table and a nut that is screwed into the screw rod is provided internally The test material is gripped by a grip provided on the lower surface of the crosshead and the upper surface of the fixed table that are moved up and down by the rotation of the screw rod, and a tensile load is applied by raising the crosshead. (See Patent Document 1).

  Further, the material testing apparatus 73 shown in FIG. 7 has a screw rod 75 using a pair of left and right ball screws standing on a fixed table 74 and a cross head 77 having a ball nut 76 screwed into the screw rod 75 disposed in the side. The test material TP gripped by the gripping tool 78 provided on the lower surface of the crosshead 77 and the upper surface of the fixed table is changed by changing the space between the fixed table 74 and the crosshead 77 that moves up and down by the rotation of the screw rod 75. It is something to load.

JP 2005-201770 A

  In conventional material testing machines, when performing repeated tests and fatigue / endurance tests with small displacements, the cross head reciprocates the micro area of the screw thread and nut threaded area with sufficient displacement. Lubricant is not replenished and wear occurs. In the case of a ball screw, the ball does not rotate and the internal hard ball is worn and damaged. Therefore, long-term repeated tests and fatigue / durability tests cannot be performed with conventional material testing machines. Further, since the crosshead is slightly displaced, the lead of the screw rod and the number of rotations are very small, and the crosshead cannot be moved at high speed.

  In order to solve the above problems, a material testing machine provided by the present invention includes a screw rod erected on a base, means for rotationally driving the screw rod, and a crosshead that moves up and down by the rotation of the screw rod. In a space between a first cross head provided on a pair of screw rods and a second cross head provided on another pair of screw rods erected on the same base. A test material is installed, and the two pairs of screw rods are rotated by their own rotational drive devices, respectively, and a load is applied to the test material due to a difference in elevation speed between the first crosshead and the second crosshead.

  In the two pairs of screw rods, the lead of one screw rod pair and the other screw rod pair are set to different values, and the two pairs of screw rods are rotated so that the vertical speed difference between the first cross head and the second cross head is different. May be provided.

  A rotation transmission component is attached to each tip of the two pairs of screw rods, and the two pairs of screw rods are synchronously rotated by connecting one rotation driving device and the rotation transmission component instead of a unique rotation driving device. be able to.

  Alternatively, in a material testing machine including a screw rod erected on a base, means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, the screw rod is an upper screw portion. A first crosshead and a lower part horizontally mounted on the upper screw portion of the screw rod are rotated in synchronism with a pair of screw rods that are divided into lower screw portions and leads of the upper screw portion and the lower screw portion are different in value. A load is applied to a test material installed in a space between the first crosshead and the second crosshead due to a difference in ascending / descending speed of the second crosshead horizontally mounted on the screw portion.

  Furthermore, in a material testing machine comprising a screw rod erected on a base, a means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, a screw is disposed above the screw rod. A first screw rod provided with a non-threaded portion at the upper portion and the lower portion, a second screw rod provided with a non-threaded portion at the upper portion of the screw rod and a screw portion at the lower portion, and a screw portion of the first screw rod, Due to a difference in elevation speed between the first cross head horizontally mounted on the non-threaded portion of the second screw rod, the non-threaded portion of the first screw rod, and the second cross head horizontally mounted on the screw portion of the second screw rod. A load is applied to a test material installed in a space between the first crosshead and the second crosshead.

  The lead of the first screw rod and the second screw rod may have different values.

  The first screw rod and the second screw rod may be rotated synchronously.

  In a material testing machine comprising a screw rod erected on a base, means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, the screw rod is divided into an upper screw portion and a lower screw. Rotate a single screw rod that is divided into two parts and the lead of the upper screw portion and the lower screw portion have different values, one screwed into the upper screw portion of the screw rod, and the other holding the test material Due to the difference in elevation speed between the first cross head provided with the tool and the second cross head provided with one of the screw threads on the lower threaded portion of the screw rod and the other provided with the gripping material for the test material, A load is applied to a test material installed in a space with the second crosshead.

  With the above configuration, the differential material testing machine of the present invention can obtain a slight displacement in the test space due to the difference in the lifting speed of the two crossheads, so the screw lead and screw rod rotation speed must be made very small. There is no.

  Since it is not necessary to make the number of revolutions of the screw rod small, local wear and damage between the screw rod and the nut of the crosshead are prevented, and the test material setup time can be shortened by the high-speed movement of the crosshead.

It is an assembly block diagram of the differential material testing machine of Example 1 of this invention. It is an assembly block diagram of the differential material testing machine of Example 2 of this invention. It is an assembly block diagram of the differential type material testing machine of Example 3 of this invention. It is an assembly block diagram of the differential material testing machine of Example 4 of this invention. It is an assembly lineblock diagram of a differential type material testing machine of Example 5 of the present invention. It is an assembly block diagram of the differential type material testing machine of the modification of this invention. It is an assembly block diagram of the conventional material testing machine.

  In a material testing machine comprising a screw rod erected on a base, a means for rotationally driving the screw ク ロ ス, and a cross head that moves up and down by the rotation of the screw 一 対, a pair of erected on the base A test material is installed in a space between the cross head provided on the other screw rod and the cross head provided on the other pair of screw rods erected on the same base, and the two pairs of screw rods are Each of them is rotated by its own rotation drive device, and a load is applied to the test material by the difference in the lifting speed of both crossheads. This will be described below with reference to the drawings.

  A first embodiment provided by the present invention is shown in FIG. 1A is a front assembly configuration diagram of the differential material testing machine of the present invention, FIG. 1B is a cross-sectional view taken along the line AA, and FIG. 1C is a cross-sectional view taken along the line BB. FIG.1 (d) shows CC sectional drawing.

  A differential material testing machine 1 according to the present invention includes a ball nut 4a screwed into each of a pair of ball screw rods 3a and 3b erected in one diagonal direction of a rectangular base 2 as shown in FIG. 4b are provided in the left and right sides, and a first cross head 5 horizontally mounted on top of the ball screws 3a and 3b and a pair of ball screws 6a and 6b installed in the other diagonal direction of the base 2, respectively. The ball nuts 7a and 7b that are screwed into the right and left are provided in the left and right, and the second cross head 8 that is mounted horizontally below the ball screw rods 6a and 6b and the test that is suspended downward from the center of the first cross head 5 A gripping tool 9 for the material TP and a gripping tool 10 for the test material TP suspended upward in the center of the second crosshead 8, and a rotary drive device 11 for ball screws 3a and 3b for raising and lowering the first crosshead 5 described later. And a bow to raise and lower the second crosshead 8 Threaded rod 6a, and a rotary drive device 12. of 6b.

  The centers of the gripping tool 9 provided on the first crosshead 5 and the gripping tool 10 provided on the second crosshead 8 are disposed on the same vertical line H (see FIG. 1B).

  As shown in FIG. 1, the rotary drive device 11 is disposed in the upper region of the lower space 13 of the base 2. The ball screw rods 3a and 3b are supported by bearings 14a and 14b provided in the base 2 as shown in FIG. 1 (d), and gears 15a and 15b having the same specifications are provided at the front ends protruding from the bearings toward the lower space 13 side. Is inserted. A toothed belt 16 that synchronously rotates the ball screw rods 3a and 3b is engaged with the gears 15a and 15b, and a gear 15c that is fitted to the output shaft of the electric motor 17 is engaged with the gear 15b.

  As shown in FIG. 1, the rotary drive device 12 is disposed in a lower region of the lower space 13 of the base 2. The ball screw rods 6a and 6b are supported by bearings 18a and 18b provided in the base 2 as shown in FIG. 1 (d), and gears 19a and 19b having the same specifications are provided at the tip portion protruding from the bearing toward the lower space 13 side. Is inserted. A toothed belt 20 that synchronously rotates the ball screw rods 6a and 6b is engaged with the gears 19a and 19b, and a gear 19c that is fitted to the output shaft of the electric motor 21 is engaged with the gear 19a.

  The differential material testing machine 1 of the present invention configured as described above has two pairs of ball screw rods 3a, 3b and 6a, 6b with leads L, ball screw rods 3a, 3b with a rotational speed N1, ball screw rod 6a, If the rotational speed of 6b is N2, the amount of change ΔS of the test space S between the first crosshead 5 and the second crosshead 8 is given by (N1−N2) L, and when N1> N2, the amount of change ΔS is The tensile force can be applied to the test material TP in the test space S with a positive value. When N1 <N2, the amount of change ΔS can be a negative value and the compressive force can be applied to the test material TP. it can.

  Further, the lead L of the ball screw rods 3a and 3b and the lead L1 of the ball screw rods 6a and 6b may have different values. In this case, the change amount ΔS of the test space S between the first crosshead 5 and the second crosshead 8 is given by (N1, L−N2, L1), the lead L of the ball screw rods 3a, 3b and the rotational speed N1. Is larger than the product of the lead L1 of the ball screw rods 6a and 6b and the rotational speed N2, the change amount ΔS becomes a positive value, and a tensile force is applied to the test material TP in the test space S, and in the opposite case, the change amount. ΔS becomes a negative value, and a compressive force is applied to the test material TP.

  As described above, in the differential material testing machine 1 according to the present invention, the slight change amount ΔS of the test space S can be obtained by the difference in the vertical speed of the upper and lower cross heads, so there is no need to make the rotational speed of the ball screw rod small. As in the conventional material testing machine, the fine displacement of the ball screw rod and the nut is reciprocated by the slight displacement of the cross head, and local wear due to lack of lubricating liquid at the contact portion can be prevented. In addition, since it is not necessary to make the rotation speed of the ball screw rod small, it is possible to shorten the time for changing the test material by high-speed movement of the cross head.

  A second embodiment provided by the present invention is shown in FIG. 2 (a) is a front assembly configuration diagram of the differential material testing machine of Example 2, FIG. 2 (b) is an AA arrow sectional view, FIG. 2 (c) is a BB arrow sectional view, FIG.2 (d) shows CC sectional drawing.

  The differential material testing machine 22 of the second embodiment is based on the configuration of the first embodiment, and includes two pairs of ball screw rods 3a, 3b and 6a, 6b erected on a rectangular base 2 as shown in FIG. The values of the leads are different from each other, and the two pairs of ball screw rods 3a, 3b and 6a, 6b are synchronously rotated by a rotation driving device described later. In addition, since the structure above the base 2 is the same as that of Example 1, description is abbreviate | omitted.

  The rotation drive device 23 is disposed in the lower space 13 of the base 2 as shown in FIG. Two pairs of ball screw rods 3a, 3b and 6a, 6b are supported by bearings 14a, 14b and 18a, 18b provided in the base 2 as shown in FIG. 2 (d), and as shown in FIG. 2 (c). The gears 24 having the same specifications are fitted to the tip ends of the ball screw rods 3a, 3b and 6a, 6b projecting from the respective bearings to the lower space 13 of the base 2, and two pairs of ball screw rods 3a, A toothed belt 25 that rotates 3b and 6a, 6b synchronously is engaged. An electric motor 27 is connected to the tip of the ball screw rod 3 b to which the gear 24 is fitted via a power transmission device 26.

  The differential material testing machine 22 of Example 2 configured as described above is configured such that the leads of the ball screw rods 3a and 3b are L, the leads of the ball screw rods 6a and 6b are L1, two pairs of ball screw rods 3a, 3b and 6a, When the synchronous rotation speed of 6b is N, the change amount ΔS of the test space S between the first crosshead 5 and the second crosshead 8 is given by (L−L1) N, and when L> L1, the change amount ΔS is The tensile force can be applied to the test material TP in the test space S with a positive value. When L <L1, the change amount ΔS can be a negative value and the compressive force can be applied to the test material TP. it can.

  A third embodiment provided by the present invention is shown in FIG. 3A is a front assembly configuration diagram of the differential material testing machine of Example 3, FIG. 3B is a cross-sectional view taken along the line AA, and FIG. 3C is a cross-sectional view taken along the line BB. Show.

  As shown in FIG. 3, the differential material testing machine 28 according to the third embodiment is provided with a pair of screw portions G of a lead L standing on a base 29 at an upper portion and a screw portion J of a lead L1 at a lower portion. Ball screw rods 30a and 30b and ball nuts 31a and 31b screwed into the screw portion G are provided on the left and right sides, a first cross head 32 horizontally mounted on the upper screw portion G of the ball screw rods 30a and 30b, and a lower screw Ball nuts 33 a and 33 b that are screwed into the portion J are provided on the left and right sides, and the second cross head 34 that is horizontally mounted on the lower screw portion J of the ball screw rods 30 a and 30 b and the first cross head 32 vertically downward The test material TP gripping tool 9 provided at the center, the test material TP gripping tool 10 provided vertically upward in the center of the second cross head 34, and a rotation driving device 35 described later for synchronously rotating the ball screw rods 30a and 30b. From It has been made.

  The rotation drive device 35 is disposed in the lower space 36 of the base 29 as shown in FIG. The pair of ball screw rods 30a and 30b are supported by bearings 37a and 37b provided in the base 29, and the gear screws 38a and 30b having the same specifications are provided at the tip portions of the ball screw rods 30a and 30b protruding from the bearings toward the lower space 36. 38b is fitted, and a toothed belt 39 for synchronously rotating the ball screw rods 30a and 30b is engaged. The tip of the ball screw rod 30b to which the gear 38b is fitted is connected to the electric motor 41 through the power transmission device 40.

  In the differential material testing machine 28 according to the third embodiment configured as described above, the change in the test space S between the first crosshead 32 and the second crosshead 34 when the rotational speed of the ball screw rods 30a and 30b is N. The amount ΔS is given by (L−L1) N, and when L> L1, the amount of change ΔS becomes a positive value, and a tensile force can be applied to the test material TP in the test space S. When L <L1 The amount of change ΔS becomes a negative value, and a compressive force can be applied to the test material TP.

  A fourth embodiment provided by the present invention is shown in FIG. 4 (a) is a front assembly configuration diagram of the differential material testing machine of Example 4, FIG. 4 (b) is a cross-sectional view taken along the line AA, and FIG. 4 (c) is a cross-sectional view taken along the line BB. Show.

  The differential material testing machine 42 of Example 4 is erected on a base 43 as shown in FIG. 4, and a ball screw rod 44a divided into two by providing a screw part G at the upper part and a non-screw part P at the lower part, A ball screw rod 44b divided into two by providing a non-threaded portion Q and a threaded portion J below, a ball nut 45a screwed into the threaded portion G, and a bearing 46b fitted into the non-threaded portion Q are provided on the left and right. A first cross head 47 horizontally mounted on the threaded portion G and the non-threaded portion Q, a ball nut 45b that is screwed to the threaded portion J, and a bearing 46a that is fitted into the non-threaded portion P are provided on the left and right sides. A second crosshead 48 horizontally mounted on the part J and the non-threaded part P, a grip 9 for the test material TP provided vertically downward at the center of the first crosshead 47, and the center of the second crosshead 48 A gripping tool 10 for the test material TP provided vertically upward on the ball and a ball screw And it is configured to 44a and 44b from the rotary drive unit 49 and 50 described later to rotate.

  The rotation driving devices 49 and 50 are disposed in the lower space 51 of the base 43 as shown in FIG. The ball screw rods 44a and 44b are supported by bearings 52a and 52b provided in the base 43, and power transmission devices 53a and 53b are provided at the tip portions of the ball screw rods 44a and 44b protruding from the bearings toward the lower space 51, respectively. The electric motors 54a and 54b are connected via each other.

  In the differential material testing machine 42 of Example 4 configured as described above, the rotation speed of the ball screw rod 44a is N1, the rotation speed of the ball screw rod 44b is N2, and the leads of the screw portion G and the screw portion J are L. Then, the change amount ΔS of the test space S between the first crosshead 47 and the second crosshead 48 is given by (N1−N2) L, and when N1> N2, the change amount ΔS becomes a positive value and the test space. A tensile force can be applied to the test material TP of S. When N1 <N2, the amount of change ΔS becomes a negative value, and a compressive force can be applied to the test material TP.

  The lead of the screw part G and the lead of the screw part J may be different values. When the lead of the screw portion G is L and the lead of the screw portion J is L1, the change amount ΔS of the test space S between the first crosshead 47 and the second crosshead 48 is (N1 · L−N2 · L1). When the product of the lead L of the screw part G and the rotation speed N1 of the ball screw rod 44a is larger than the product of the lead L1 of the screw portion J and the rotation speed N2 of the ball screw rod 44b, the variation ΔS becomes a positive value. A tensile force is applied to the test material TP in the test space S, and in the opposite case, the change amount ΔS becomes a negative value and a compressive force is applied to the test material TP. Further, when the lead L of the screw portion G and the lead L1 of the screw portion J have different values, the rotation speed N1 and the rotation speed N2 may be the same. At this time, the rotation driving devices 49 and 50 may be provided as one unit to rotate the ball screw rods 44a and 44b synchronously.

  A fifth embodiment provided by the present invention is shown in FIG. FIG. 5 shows a side assembly diagram of the differential material testing machine of the fifth embodiment.

  As shown in FIG. 5, the differential material testing machine 55 of the fifth embodiment is a single ball screw in which a screw portion G of a lead L is provided on an upper portion of a base 56 and a screw portion J of a lead L1 is provided on a lower portion. A first crosshead screwed into the threaded portion G through a flange 57 and a ball nut 58 threadedly engaged with the threaded portion G provided on the other side with the gripping tool 9 for the test material TP on one side. 59, and a second crosshead 61 screwed into the threaded portion J through a ball nut 60 threadedly engaged with the threaded portion J provided on the other side with the gripping tool 10 of the test material TP on one side. And a rotation driving device 62 of a ball screw rod 57 described later.

  The rotation drive device 62 is disposed in the lower space 63 of the base 56. The ball screw rod 57 is supported by a bearing 64 provided in the base 56, and the tip of the ball screw rod 57 protruding from the bearing 64 toward the lower space 63 is connected to an electric motor 66 through a power transmission device 65. Yes.

  Further, in order to prevent the cross head from rotating, a groove 68 is provided vertically on the side of the column 67 facing the ball screw rod 57 that is erected on the base 56 in parallel with the ball screw rod 57, Projections 69 and 70 provided on the side opposite to the gripping tool with respect to the ball screw rod 57 of the second cross head 61 are slidably inserted into the groove 68.

  In the differential material testing machine 55 of Example 5 configured as described above, the change in the test space S between the first crosshead 59 and the second crosshead 61 when the rotational speed of the ball screw rod 57 is N. The amount ΔS is given by (L−L1) N. When L> L1, the amount of change ΔS becomes a positive value, and a tensile force can be applied to the test material TP in the test space S, and L <L1 In this case, the change amount ΔS becomes a negative value, and a compressive force can be applied to the test material TP.

  The features of the differential material testing machine provided by the present invention are as described above. However, the present invention is not limited to the above and illustrated examples. For example, FIG. It is installed horizontally on the GL. FIG. 6A shows a top view of the differential material testing machine 28 installed horizontally, and FIG. 6B shows a cross-sectional view taken along the line AA.

  In the case of horizontal installation, in order to prevent the ball screw rods 30a and 30b from being bent due to the weight of the first cross head 32 and the second cross head 34 which are horizontally mounted on the ball screw rods 30a and 30b, the first cross head 32 and the second cross head 32 Wheels 71 and 72 that are rotatable in the direction of movement of the crosshead are provided on the grounding side of the crosshead 34. This modification is effective for installation in an environment restricted in the height direction.

  Further, the present modification is not limited to the third embodiment, and can be applied to a material testing machine using various crossheads. Furthermore, it is also possible to use a chain and a sprocket instead of a gear and a toothed belt as a rotational drive system. The present invention encompasses all of these.

  Uses a general-purpose electric motor and rotation control device to obtain a small amount of change in the crosshead, enables long-term repeated tests and durability tests, and further shortens the setup change time for industrial use. It is.

DESCRIPTION OF SYMBOLS 1 Differential type material testing machine 2 Base 3a, 3b Ball screw rod 4a, 4b Ball nut 5 1st crosshead 6a, 6b Ball screw rod 7a, 7b Ball nut 8 Second crosshead 9, 10 Grasping tool 11, 12 Rotation drive Device 13 Lower space 14a, 14b Bearing 15a, 15b, 15c Gear 16 Toothed belt 17 Electric motor 18a, 18b Bearing 19a, 19b, 19c Gear 20 Toothed belt 21 Electric motor 22 Differential material testing machine 23 Rotation drive device 24 Gear 25 Toothed belt 26 Power transmission device 27 Electric motor 28 Differential material testing machine 29 Base 30a, 30b Ball screw rod 31a, 31b Ball nut 32 First cross head 33a, 33b Ball nut 34 Second cross head 35 Rotation drive device 36 Lower part Space 37a, 37b Bearing 38a, 38b Gear 39 Toothed belt 4 0 Power transmission device 41 Electric motor 42 Differential material testing machine 43 Bases 44a, 44b Ball screw rods 45a, 45b Ball nuts 46a, 46b Bearing 47 First cross head 48 Second cross head 49, 50 Rotation drive device 51 Lower space 52a , 52b Bearings 53a, 53b Power transmission devices 54a, 54b Electric motor 55 Differential material testing machine 56 Base 57 Ball screw rod 58, 60 Ball nut 59 First crosshead 61 Second crosshead 62 Rotation drive device 63 Lower space 64 Bearing 65 Power transmission device 66 Electric motor 67 Prop 68 Groove 69, 70 Protruding portion 71, 72 Wheel 73 Material testing device 74 Fixed table 75 Screw rod 76 Ball nut 77 Cross head 78 Grasp G, J Screw portion H Vertical line P, Q Non Thread part S Test space TP Test material GL Horizontal plane

Claims (8)

  In a material testing machine comprising a screw rod erected on a base, means for rotationally driving the screw rod, and a crosshead that moves up and down by the rotation of the screw rod, a first provided on a pair of screw rods Place the test material in the space between one crosshead and the second crosshead provided on the other pair of screw rods erected on the same base, and rotate the two pairs of screw rods independently. A differential material testing machine characterized in that a load is applied to a test material by a difference in ascending / descending speed between a first cross head and a second cross head by being rotated by a driving device.   In the two pairs of screw rods, the lead of one screw rod pair and the other screw rod pair are set to different values, and the two pairs of screw rods are rotated so that the difference in elevation speed between the first cross head and the second cross head is obtained. The differential material testing machine according to claim 1, wherein the differential material testing machine is provided.   A rotation transmission component is attached to each tip of the two pairs of screw rods, and the two pairs of screw rods are synchronously rotated by connecting one rotation driving device and the rotation transmission component instead of a unique rotation driving device. The differential material testing machine according to claim 2, wherein:   In a material testing machine comprising a screw rod erected on a base, means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, the screw rod is divided into an upper screw portion and a lower screw. A first cross head and a lower screw portion that are horizontally mounted on the upper screw portion of the screw rod, and a pair of screw rods having different values for the upper screw portion and the lower screw portion are synchronously rotated. A differential material characterized in that a load is applied to a test material installed in a space between the first crosshead and the second crosshead due to a difference in ascending / descending speed of a second crosshead mounted horizontally testing machine.   In a material testing machine comprising a screw rod erected on a base, a means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, a screw portion and a lower portion above the screw rod A first screw rod provided with a non-threaded portion and a second screw rod provided with a non-threaded portion on the upper portion of the screw rod and a second screw rod provided with a screw portion on the lower portion thereof are rotated by their own rotating devices, respectively. Ascending and descending of the first crosshead horizontally mounted on the screw portion and the non-threaded portion of the second screw rod, and the second crosshead horizontally mounted on the non-threaded portion of the first screw rod and the screw portion of the second screw rod. A differential material testing machine that applies a load to a test material installed in a space between the first crosshead and the second crosshead due to a speed difference.   6. The differential material testing machine according to claim 5, wherein the first screw rod and the second screw rod have different leads.   The differential material testing machine according to claim 6, wherein the first screw rod and the second screw rod are rotated synchronously.   In a material testing machine comprising a screw rod erected on a base, means for rotationally driving the screw rod, and a cross head that moves up and down by the rotation of the screw rod, the screw rod is divided into an upper screw portion and a lower screw. Rotate a single screw rod that is divided into two parts and the lead of the upper screw portion and the lower screw portion have different values, one screwed into the upper screw portion of the screw rod, and the other holding the test material Due to the difference in elevation speed between the first cross head provided with the tool and the second cross head provided with one of the screw threads on the lower threaded portion of the screw rod and the other provided with the gripping material for the test material, A differential material testing machine for applying a load to a test material installed in a space between the second crosshead.

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