JPH11281349A - Elongation measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to position a pair of levers accurately at an initial position by pushing the levers near to the initial position, together with a load member moving to a test start position, and extending an extending means to the load member. SOLUTION: On a test piece a pair of levers 14U, 14L are mounted and a tension test is applied to the test piece through a load member 4 while the travel distances of the levers 14U, 14L according to the elongation of the test piece are measured. Push members 22, 33 interlock with the load member 4 moving to a test start position and push the levers 14U, 14L near to an initial position. An air cylinder 22 extends to the load member 4 to move and position the levers 14U, 14L located near the initial position to the initial position. Thus it is possible to return the levers 14U, 14L to the initial position a simple constitution, without manual means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lever type elongation measuring device for measuring the elongation of a test piece such as rubber or plastic subjected to a tensile test.

[0002]

2. Description of the Related Art As a lever-type elongation measuring device, a pair of levers are respectively mounted on the upper and lower marked lines of a test piece, and the pair of levers are moved along a guide rod in accordance with the elongation of the test piece. It is known to measure the elongation of a test piece by detecting the amount of movement of each test piece.

[0003]

In this type of elongation measuring apparatus, it is necessary to return the pair of levers to the initial position after the test is completed in preparation for the next test. , The workability is poor, and it hinders the automation of the test.

An object of the present invention is to provide an elongation measuring device which can return a pair of levers to an initial position accurately with a simple configuration without manual operation.

[0005]

FIG. 1 shows an embodiment of the present invention.
The present invention has a pair of levers 14U and 14L attached to a test piece TP,
When a tensile test is performed on the test piece TP through the test piece, the present invention is applied to an elongation measuring device that measures the amount of movement of a pair of levers 14U and 14L that move according to the elongation of the test piece TP. Further, push means 22 and 23 for pushing the pair of levers 14U and 14L to near the initial position in conjunction with the movement of the load member 4 to the test start position are provided. A pair of levers 14U, 14L near the initial position
Is provided to extend and retract to the initial position, thereby solving the above problem.

[0006] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments are used to make the present invention easier to understand. However, the present invention is not limited to this.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. In FIG. 2 showing a material testing machine, a pair of screw rods 2 erected on a table 1 is horizontally crossed with a cross yoke 3 at the upper part and both ends of a crosshead 4 are screwed together. As a result, the crosshead 4 moves up and down. Upper and lower grips 5, 6 are coaxially attached to the crosshead 4 and the table 1, respectively. The gripper 5, 6 grips both ends of the test piece TP, raises the crosshead 4, and pulls the test piece TP. Apply a load. Reference numeral 7 denotes a cover that covers the screw rod 2.

An elongation measuring device 10 for measuring the inter-gauge elongation of the test piece TP is provided behind the crosshead 4. This elongation measuring device 10 is, as shown in FIG.
1, a pair of upper and lower levers 14U, 14L provided on the guide rod 13 via a linear bearing 14a so as to be able to move up and down, and a lever 1
It has rotary encoders 15U and 15L for detecting the movement amounts of 4U and 14L, respectively. Up and down lever 14U,
14L has a pair of gripping pieces CP as shown in FIG. 1 (a), and the gripping pieces CP
Opens and closes to grip / open the test piece TP. When the test piece TP extends upward while holding the test piece TP, the levers 14U and 14L move up following the extension. Stoppers ST1 and ST2 for regulating the elevation of the levers 14U and 14L are provided on upper and lower portions of the guide rod 13.

As shown in FIG. 3, the upper and lower levers 14U,
The wires 16U and 16L connected to the 14L
Are respectively wrapped around a pair of pulleys 17U, 17L provided at the upper part of the, and weights 18U, 18L are attached to the other ends. With the elongation of the test piece TP, the upper and lower levers 14U,
When 14L rises, the weights 18U, 18L fall, and the pulleys 17U, 17L are rotated by the wires 16U, 16L, respectively, and the amount of rotation is determined by the rotary encoder 15U,
Detect at 15L. The outputs of the encoders 15U and 15L depend on the amounts of movement of the upper and lower levers 14U and 14L, respectively, and the extension of the test piece TP is obtained from both outputs.

As shown in FIG. 4, a GL setting rod 19 is implanted in the lower lever 14L. When the upper lever 14U comes into contact with the GL setting rod 19, the distance between the levers becomes equal to the distance between the marked lines of the test piece TP. Become. By appropriately changing the length of the GL setting rod 19, it is possible to cope with a plurality of test pieces TP having different gauge lengths.

An air cylinder 22 is attached to the crosshead 4 via a bracket 21, and a pressing rod 23 connected to a piston rod thereof can be brought into contact with a contact portion 14b of an upper lever 14U. As shown in FIG. 5, an electromagnetic valve 31 is provided between the air cylinder 22 and the pneumatic pressure source 33. The switching of the electromagnetic valve 31 causes the air cylinder 22 to expand, contract and lock as described later. Air cylinder 2
The expansion and contraction speed of the crosshead 4 is determined by the rotation of the screw rod 2.
Is set to be sufficiently slower than the moving speed of.

FIG. 6 is a block diagram of a control system for controlling the material testing machine and the elongation measuring device. The control device 51 is a testing machine control device including the above-described electromagnetic valve 31, a gripping piece opening / closing device 52 for driving the opening / closing member 14c (FIG. 1A), a screw rod drive motor driving device, a gripper opening / closing device, and the like. 53 and the rotary encoder 15U,
The detection output of 15 L is input and the elongation of the test piece is calculated.

FIG. 7 is a flowchart for explaining the procedure of a fully automatic tensile test executed by the controller 51.
When the test start operation is performed, a test piece supply device (not shown) is driven to supply the test piece TP between the pair of grips 5 and 6 (step S1), and the upper and lower grips 5 are moved by the gripper opening / closing device. , 6 are closed to grip the test piece TP (step S2). At this time, the crosshead 4 is located at the test start position (initial position) shown in FIG. 1, the upper and lower levers 14U, 14L of the elongation measuring device 10 are also at the initial position shown in FIG. 1, and the linear bearing 14a of the lower lever 14L. Is in contact with the stopper ST2, and its lowering is regulated. The lever interval is the distance between the marked lines of the test piece TP by the GL setting rod 19, and therefore, the gripping piece CP of the levers 14U and 14L is
By closing the lever 14U, as shown in FIG.
14L is mounted on the upper and lower mark lines of the test piece TP (step S3).

When the solenoid valve 31 is switched to the left position in the figure, the air cylinder 22 contracts and the holding rod 23 is moved to the upper lever 14.
Move away from U (step S4). When contracted by a predetermined amount, the solenoid valve 31 is switched to the neutral position to lock the air cylinder 22, and then the pair of screw rods 2 is rotated forward, so that the crosshead 4 is raised and a tensile load acts on the test piece TP ( Step S5). When the test piece TP is extended along with this, the upper and lower levers 14U and 14L are raised while being guided by the guide rod 13 following the extension. Lever 14U, 1
The weights 18U, 18L are lowered by the rise of 4L, and the pulleys 17U, 17L rotate, and the amount of rotation is sequentially detected by the rotary encoders 15U, 15L.

When the conditions for terminating the test, such as breakage of the test piece TP, are satisfied, step S6 is affirmed and step S7 is performed.
And the test piece TP is removed. The screw rod 2 is reversed to prepare for the next test, and the crosshead 4 is lowered to the initial position (step S8). The air cylinder 22 is lowered integrally with the lowering of the crosshead 4, and the tip of the pressing rod 23 comes into contact with the contact portion 14b of the upper lever 14U. Since the air cylinder 22 is locked, the upper lever 14 </ b> U is pressed downward by the presser bar 23 and descends integrally with the crosshead 4. When the upper lever 14U comes into contact with the GL setting rod 19, the lower lever 14L also moves down integrally, and
When they reach the initial position and stop, the upper and lower levers 14U, 14
L also stops. At this time, the levers 14U and 14L are lowered to near the initial position, but not completely at the initial position, and there is a gap S between the linear bearing 14a and the stopper ST2 as shown in FIG.

When the solenoid valve 31 is switched to the right position, the air cylinder 22 is extended, the holding rod 23 pushes down the upper lever 14U, and the vertical lever 14U,
14L descends integrally (step S9). Lower lever 1
When the 4L linear bearing 14a comes into contact with the stopper ST2 (when the levers 14U and 14L reach the initial position), the lowering of the levers 14U and 14L is prevented. Thereafter, the solenoid valve 31 is switched to the neutral position to switch the air cylinder 22 to the neutral position.
To stop. Thereafter, the process returns to step S1 and is repeated.

As described above, in this embodiment, the elongation measuring device 10 is used by utilizing the descent of the crosshead 4 to the initial position.
The upper and lower levers 14U, 14L are lowered to near the initial position, and then are positioned at the initial position by the air cylinder 22. It can be returned to the position. Especially the air cylinder 22
The following effects can be obtained by using. That is, if the levers 14U and 14L are driven to the initial position only by the movement of the crosshead 4, a large impact is applied when the linear bearing 14a comes into contact with the stopper ST2 due to a fast descending speed, and the lever may be damaged. is there. In addition, in order for the levers 14U and 14L to accurately reach the initial position when the crosshead 4 reaches the initial position, high precision is required in the dimensions of the members connecting the two, which increases costs. Since the expansion / contraction speed of the air cylinder 22 is sufficiently lower than the moving speed of the crosshead 4,
Ultimately, positioning by using the air cylinder 22 does not give a large impact, so that damage to the lever can be prevented. In addition, the member such as the presser bar 23 does not need to have a high dimensional accuracy, so that the cost can be reduced.

In the above embodiment, the crosshead 4 uses the load member as the air cylinder 22 and the holding rod 23.
Constitutes a pushing means, and the air cylinder 22 constitutes a telescopic means.

In the above description, the lever 14U, the lever 14U is held by the holding rod 23 attached to the piston rod of the air cylinder 22.
Although 14L is pushed down, it may be pushed down directly by an air cylinder. In the case where the GL setting rod is not used, two pressing members having different lengths for pressing the upper and lower levers are attached to the air cylinder, and return to their initial positions while maintaining a predetermined distance between the two levers. Is also good. Further, the method of detecting the lever movement amount is not limited to the above method, and for example, a method using a differential transformer or the like may be used.

[0020]

According to the present invention, after the pair of levers are pushed to near the initial position in conjunction with the movement of the load member to the test start position, the pair of levers are positioned at the initial position by the telescopic means. Therefore, the lever can be returned to the initial position without manual operation and with a simple configuration.
In addition, the use of the expansion and contraction means can reduce the impact when the lever reaches the initial position, and prevent the lever from being damaged.

[Brief description of the drawings]

FIG. 1 shows an elongation measuring apparatus according to the present invention, wherein (a) is a cross-sectional view taken along the line aa of (b), and (b) is a side view.

FIG. 2 is a front view of the material testing machine.

FIG. 3 is a conceptual diagram showing the principle of elongation measurement.

FIG. 4 is a side view showing a state where the levers 14U and 14L have moved to near an initial position.

FIG. 5 is a drive circuit diagram of the air cylinder 4.

FIG. 6 is a block diagram of a control system.

FIG. 7 is a flowchart showing a test procedure.

FIG. 8 is a diagram showing a state in which a lever is mounted on a test piece.

[Explanation of symbols]

 Reference Signs List 4 Crosshead 10 Elongation measuring device 12 Support 13 Guide rod 14U, 14L Vertical lever 14a Linear bearing 15U, 15L Rotary encoder 16U, 16L Wire 17U, 17L Pulley 18U, 18L Weight 19GL setting rod 22 Air cylinder 23 Press rod 31 Electromagnetic valve 51 Controller ST1, ST2 Stopper

Claims (1)

[Claims] The present invention has a pair of levers attached to a test piece, and measures a movement amount of the pair of levers that move according to the elongation of the test piece when a tensile test is performed on the test piece via a load member. In the elongation measuring device, the pushing member is provided with pushing means for pushing the pair of levers to near the initial position in conjunction with the movement of the load member to the test start position, and the pushing means is provided with respect to the load member. An elongation measuring apparatus, comprising: an expansion / contraction means for moving a pair of levers located near the initial position by being extended to position the lever at an initial position.