JP4052989B2 - Elastic modulus measuring device - Google Patents

Description

  The present invention relates to an elastic modulus measuring apparatus, and more particularly to an elastic modulus measuring apparatus that enables a wide range of measurement from a minute displacement region to a large displacement region by mounting a test piece once.

  When measuring the elastic modulus of a metal material, etc., hold both ends of a standard test piece with a tensile and compression tester, and when measuring the tensile elastic modulus, apply a tensile load to the test piece, In the case of compressive load, in the case of flexural modulus, the bending load is applied, and the shape change of the test piece at that time is obtained as the amount of displacement between the marked lines marked on the test piece. The tensile, compressive, and flexural moduli were obtained from the values and displacement.

  FIG. 6 shows a main part of such an elastic modulus measuring apparatus. In the figure, reference numerals 1 and 2 denote upper and lower jaws that sandwich both ends of the test piece S. At the marked line position of the test piece S, an extensometer 4 having a strain gauge 3 is connected to a pair of locking clips 5. Installed in.

  In this measuring apparatus, the upper and lower jaws 1 and 2 are driven by an electric ball screw or the like, a load is applied to the test piece S, and the elongation of the test piece S at that time is detected by the strain gauge 3 to detect the tensile elastic modulus. In this case, relatively high decomposition performance can be obtained by amplifying the electric signal transmitted from the strain cage 3.

  Further, for example, in Patent Documents 1 and 2, in place of the extensometer 4 provided with the strain gauge 3, a mark line provided on the test piece S is imaged with a CCD camera, and a load is applied to the test piece S. An elastic modulus measuring device that measures the amount of displacement at a time by a non-contact method has also been proposed.

However, such a conventional elastic modulus measuring device has technical problems described below.
JP 63-61106 A Japanese Patent No. 3350272

  That is, the measuring device shown in FIG. 6 and the measuring devices disclosed in Patent Documents 1 and 2 measure a relatively small displacement amount, and the elongation amount of the test piece S is usually up to about 2 mm. However, it could only be measured.

  However, for example, in a hard plastic material, elastic modulus measurement is required in a wide range from a region where the amount of elongation is very small to a region where the amount of elongation is large. I couldn't.

  In this case, it is conceivable to measure the elastic modulus separately for the minute elongation region and the large elongation region using two elastic modulus measuring devices having different measurement regions. However, if the same kind of test piece is individually attached to the measuring device by such a test method, the consistency of the material is lost, and therefore the same test piece S is used. There is also a problem that the reliability of the measurement is impaired if the attachment / detachment of S is troublesome and the attachment / detachment position is different.

  The present invention has been made in view of such conventional problems, and its object is to measure a wide range from a minute displacement region to a large displacement region by mounting a test piece once. An object of the present invention is to provide an elastic modulus measuring apparatus that enables the above.

  In order to achieve the above object, the present invention holds the both ends of the test piece, and holds the lower jaw part and the central part in the longitudinal direction of the test piece at a predetermined interval in the vertical direction and When a load is applied to the test piece via a lower arm part, a post that supports the upper and lower arm parts so as to be movable up and down, and the upper and lower jaw parts, the upper and lower parts with respect to the test piece are applied. An elastic modulus measuring device having a displacement measuring unit that measures a displacement amount of a holding position of the arm unit, the displacement measuring unit converts the displacement amount into a transmission amount of a parallel light beam, and detects an optical measurement device; And a mechanical measuring device that detects the displacement amount by converting the displacement amount into a movement amount in which the upper and lower arm portions move up and down along the post.

  According to the elastic modulus measuring apparatus configured as described above, when a load is applied to the test piece, the displacement measuring unit that measures the displacement amount of the clamping position of the upper and lower arm portions with respect to the test piece is configured so that the displacement amount is parallel. An optical measuring device that converts and detects the amount of transmitted light and a mechanical measuring device that converts and detects the amount of displacement into the amount of movement of the upper and lower arms along the post. In areas where the amount of displacement such as elongation is very small, the amount of displacement of the test piece can be detected by an optical measuring instrument, and in areas where the amount of displacement such as elongation is large, The amount of displacement can be measured. Such measurement can be continuously performed without removing the test piece once it is held between the upper and lower jaw portions and the upper and lower arm portions.

  The optical measuring instrument includes a projecting portion and a light receiving portion of the parallel light beams arranged to face each other, and a light shielding plate attached to each of the upper and lower arms is disposed between the projection portion and the light receiving portion. Can do.

  The projection unit, the light receiving unit, and the light shielding plate may be provided with an air pipe for ejecting air on the front surface thereof.

  The mechanical measuring instrument may be provided with a rotary encoder that detects the amount of movement of the upper and lower arms.

  The upper and lower arm portions are provided with a pair of grippers that are spring-biased in a direction in which the test piece is always clamped, and provided with an elliptical rod that opens and closes the grippers close to or apart from each other. Can do.

  The test piece may be a hard plastic.

  According to the elastic modulus measuring apparatus according to the present invention, it is possible to measure a wide range from a minute displacement region to a large displacement region by mounting the test piece once.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

  1 to 5 show an embodiment of an elastic modulus measuring apparatus according to the present invention. The elastic modulus measuring apparatus shown in these drawings includes upper and lower jaw portions 10 and 12, upper and lower arm portions 14 and 16, a post 18, and a displacement measuring portion 20.

  The upper and lower jaw portions 10 and 12 are, for example, sandwiching both ends of a test piece S made of hard plastic and applying a tensile or compressive load, and are arranged so as to face each other in the vertical direction. It is driven by a ball screw or the like (not shown). The lower jaw portion 12 is supported upright on the base 22, and the upper jaw portion 10 is supported upright on a column 23 standing on the base 22 through a bracket (not shown).

  As the test piece S, for example, as specified in ISO 3167, a multi-purpose test piece having a width of 10 mm, a thickness of 4 mm, a distance between marked lines of 50 mm, and a holding interval of 115 mm can be used. .

  The upper and lower arm portions 14 and 16 hold the central portion of the test piece S in the longitudinal direction at a predetermined interval in the vertical direction, and move up and down to the post 18 erected on the base 22. It is supported freely.

  Details of the upper and lower arm portions 14 and 16 are shown in FIGS. 3 and 4. In this embodiment, the upper and lower arm portions 14 and 16 have a predetermined interval along the longitudinal axis direction of the post 18. Are arranged and have substantially the same configuration.

  The upper and lower arm portions 14 and 16 shown in these drawings include cylindrical portions 14a and 16a, a pair of arms 14b, 16b, 14c and 16c, gripping tools 14d and 16d, and coil springs 14e and 16e. Yes.

  The cylindrical portions 14a and 16a are cylindrical bodies having both ends that are inserted through the post 18 so as to be movable up and down, and a pair of arms 14b, 16b, 14c, and 16c are fixed to one end. The pair of arms 14b, 16b, 14c, and 16c are narrow plate-like bodies, and are disposed so that the pair faces each other.

  The gripping tools 14d and 16d have a pair of sandwiching plates 140d and 160d whose outer peripheral surface on one end side is formed in a curved shape, and the sandwiching plates 140d and 160d are provided at the tips of the arms 14b, 16b, 14c and 16c, respectively. The test piece S is clamped between the curved portions of the clamping plates 140d and 160d.

  The coil springs 14e and 16e are arranged so as to extend between a pair of arms 14b, 16b, 14c, and 16c arranged to face each other, and the holding plates 140d and 160d of the gripping tools 14d and 16d always hold the test piece S. Is energized.

  Note that the member denoted by reference numeral 14f (16f) in FIG. 4 is an adjustment screw for the coil springs 14e and 16e arranged so as to be provided between the pair of arms 14b, 16b, 14c and 16c, and each clamping plate 140d. , 160d are used to prevent contact with each other when the grippers 14d, 16d are closed.

  In the case of the present embodiment, the sandwiching plates 140d and 160d of the gripping tools 14d and 16d are brought close to or away from each other between the pair of arms 14b, 16b, 14c and 16c arranged to face each other, and the elliptical rod 24 is opened and closed. Is installed.

  The elliptical rod 24 is an elliptical or elliptical rod having a major axis and a minor axis, is rotatably supported by the base 22 and is erected in parallel with the post 18.

  Fixed to the inner surface of each arm 14b, 16b, 14c, 16c so that the abutting pieces 14g, 16g are opposed to each other at a portion through which the pair of arms 14b, 16b, 14c, 16c on which the elliptical rods 24 are arranged to face each other. Then, when the elliptical rod 24 is rotated and the longer diameter side comes into contact with the contact pieces 14g and 16g, the clamping plates 140d and 160d of the gripping tools 14d and 16d are moved against the urging force of the coil springs 14e and 16e. It is spaced apart from each other and the interval is widened, so that the test piece S can be inserted between the sandwiching plates 140d and 160d.

  When the elliptical rod 24 is further rotated from this state and the short diameter side comes into contact with the contact pieces 14g and 16g, the clamping plates 140d and 160d of the gripping tools 14d and 16d are moved by the urging force of the coil springs 14e and 16e. The space | interval narrows mutually and the test piece S is clamped between the clamping plates 140d and 160d. This state is maintained by the urging force of the coil springs 14e and 16e.

  The member denoted by reference numeral 26 in FIGS. 1 and 3 is a space retaining spacer interposed between the upper and lower arm portions 14 and 16, and this spacer 26 abuts against the screw rod 26a. The roller 26b is provided, and the distance between the upper and lower arm portions 14 and 16 can be adjusted by the screwing amount of the screw rod 26a.

  Reference numeral 28 denotes a stopper whose one end abuts below the lower arm portion 16, and this stopper 28 is supported by the post 18 so as to be movable up and down, and its upper and lower positions can be adjusted by the lower limit setting collar 30. It can be done.

  On the other hand, when a load is applied to the test piece S via the upper and lower jaw parts 10 and 12, the displacement measuring unit 20 determines the displacement amount of the clamping position of the upper and lower arm parts 14 and 16 with respect to the test piece S. The basic configuration is to measure.

  In the case of the present embodiment, the displacement measuring unit 20 converts the displacement amount of the holding positions of the upper and lower arm portions 14 and 16 into the transmission amount of the parallel light beam L, and detects the displacement amount. It comprises a mechanical measuring instrument 20b that detects the upper and lower arm portions 14, 16 along the post 18 by converting them into vertical movements.

  The optical measuring instrument 20a includes a projection unit 200a, a light receiving unit 201a, and a pair of light shielding plates 202a and 203a. As shown in FIG. 2, the projection unit 200 a and the light receiving unit 201 a are attached to the tip of a support base 32 provided with a bifurcated support part erected on the base 22, and are arranged so as to face each other. Has been.

  As shown in detail in FIG. 5, the projection unit 200a has a planar parallel light beam that can cover a predetermined measurement range by diffusing a coherent light source such as a laser beam with a polygon mirror or an optical lens. L is projected toward the light receiving unit 201a.

  The light receiving unit 201a is configured by, for example, a phototransistor or CdS, receives the parallel light beam L projected from the projection unit 200a, and sends an electric signal corresponding to the amount of received light to the outside.

  The pair of light shielding plates 202a and 203a is installed between the projecting unit 200a and the light receiving unit 201a arranged to face each other. One of the light shielding plates 202 a and 203 a is attached to the upper arm portion 14, and the other light shielding plate 203 a is attached to the lower arm portion 16.

  As shown in FIG. 4, each of the light shielding plates 202 a and 203 a is attached to a mounting bracket 34 fixed to the side surface of one arm 14 c and 16 c of each arm portion 14 and 16 and supported by the bracket 34. The light shielding plates 202a and 203a are arranged so as to move up and down within the same vertical plane.

  In the case of the present embodiment, each of the light shielding plates 202a and 203a is formed in a knife edge shape at the end disposed on the optical path side. In the case of the present embodiment, as shown in detail in FIG. 5, the projection 200a, the light receiver 201a, and the light shielding plates 203a and 204a each have an air pipe 36 for ejecting air to the front surface thereof. Each is arranged.

  Providing such an air pipe 36 can eliminate measurement errors due to floating substances adhering to the surfaces of the projection unit 200a, the light receiving unit 201a, and the light shielding plates 203a and 204a. In this case, particularly in the measurement of hard plastics, the test piece S is usually manufactured by die cutting, and when a plurality of test pieces S are tested, the adhesion between the test pieces S is prevented. Therefore, if the powder is interposed between the test pieces S and measurement is performed as it is, if the fine powder is the optical measuring instrument 20a, it leads to a measurement error.

  In such a case, when air is blown onto the projection unit 200a, the light receiving unit 201a, and the light shielding plates 203a and 204a via the air pipe 36, foreign matters such as powder are removed, and in particular, a minute displacement amount is measured. In the case of the optical measuring instrument 20a, it is suitable for maintaining high accuracy.

  According to the optical measuring instrument 20a configured as described above, the displacement amount of the test piece S is detected as follows. When the load is applied to the test piece S through the upper and lower jaw parts 10 and 12 by holding the upper and lower arm parts 14 and 16 at predetermined positions of the test piece S, the elongation of the test piece S, etc. Thus, when the holding positions of the upper and lower arm portions 14 and 16 with respect to the test piece S are displaced, this displacement is transmitted to the respective light shielding plates 203a and 204a via the mounting bracket 34, and the light shielding plate is changed according to the displacement amount. 203a and 204a move up and down.

  In this case, since the light shielding plates 203a and 204a are interposed between the projection unit 200a and the light receiving unit 202a, when the light shielding plates 203a and 204a are moved in the vertical direction, they are projected from the projection unit 200a toward the light receiving unit 201a. A variation occurs in the transmission amount of the light beam L, and the variation in the transmission amount appears as a displacement amount of the light beam received by the light receiving unit 201a, and the light receiving unit 201a detects this displacement amount. That is, in the case of the present embodiment, the optical measuring instrument 20a detects the displacement amount of the clamping position of the upper and lower arm portions 14 and 16 by converting it into the transmission amount of the parallel light beam L.

  On the other hand, as shown in FIG. 3, the mechanical measuring instrument 20b has a rotary encoder 200b that detects the amount of movement of the upper and lower arm portions 14, 16 up and down. The rotary encoder 200b is coupled to the upper and lower arm portions 14 and 18 via the metal wire 201b. When the upper and lower arm portions 14 and 16 move in the vertical direction, the amount of movement is detected by the rotary encoder 200b. It has come to be.

  The downward movement amounts of the upper and lower arm portions 14 and 16 detected by the rotary encoder 200b are determined by the gripping tools 14d and 16d of the arm portions 14 and 16 holding the central portion of the test piece S. In the mechanical measuring instrument 20b, the displacement amount of the test piece S is detected by converting the displacement amount of the test piece S into the movement amount in which the upper and lower arm portions 14 and 16 move up and down along the post 18. is doing.

  Now, according to the elastic modulus measuring apparatus configured as described above, first, the elliptical rod 24 is rotated so that the long diameter of the elliptical rod 24 contacts the contact pieces 14g and 16g, and the gripping tools 14d and 16d are opened. The test piece S is inserted between them, and the test piece S is clamped so that the short diameter of the elliptical rod 24 contacts the contact pieces 14f and 16f.

  Next, when the upper and lower ends of the test piece S are held between the upper and lower jaw portions 10 and 12, preparation for measurement is completed. Next, the upper and lower jaw portions 10 and 12 are moved, for example, in directions away from each other, and a tensile load is applied to the test piece S, and the elongation amount is measured by the optical measuring instrument 20a and the mechanical measuring instrument 20b. To do. When the amount of elongation is measured, the tensile modulus is obtained from the applied load value and the amount of elongation.

  In this case, the measurement by the optical measuring instrument 20a is up to a position where the light shielding plates 203a and 204a can shield the parallel light beam L, and this position is, for example, a minute extension in which the displacement amount of the test piece S is about 25 to 125 μm. It is considered as an area. And the measurement of a large elongation region of 125 μm or more is continuously performed by the mechanical measuring instrument 20b.

  Usually, regarding the test of plastic material, in the case of a test piece that does not show a yield phenomenon,% strain, tensile strain, tensile fracture strain, or for a test piece that shows a yield phenomenon,% strain, tensile strain, tensile fracture strain, It is specified that the tensile initial elastic modulus is measured between the marked lines of the test piece S together with the tensile strength strain and the like. In this case, the initial elastic modulus that needs to be measured with high accuracy and high resolution needs to be measured with the same test piece at the same time as the same test piece as part of other test items. Can fully respond to.

  Now, according to the elastic modulus measuring apparatus configured as described above, when a load is applied to the test piece S, a displacement measurement that measures the amount of displacement of the clamping positions of the upper and lower arm portions 14 and 16 with respect to the test piece S. The unit 20 converts the amount of displacement into an optical measuring device 20a that detects the amount of parallel light by transmitting it, and converts the amount of displacement into the amount of movement that the upper and lower arm portions 14, 16 move up and down along the post 18. Since the mechanical measuring device 20b is provided for detection, the displacement amount of the test piece S by the optical measuring device 20a can be detected in an area where the displacement amount such as the elongation amount is very small, and the elongation amount or the like. In the region where the amount of displacement increases, the amount of displacement of the test piece S by the mechanical measuring instrument 20b can be measured. In such a measurement, once the test piece S is held between the upper and lower jaw portions 10 and 12 and the upper and lower arm portions 14 and 16, the measurement can be performed without removing the test piece S, and the measurement can be automated. Become.

  The elastic modulus measuring apparatus according to the present invention can be effectively used for measuring elastic modulus in a wide range from a minute displacement region such as a hard plastic to a large displacement region.

It is a side view which shows one Example of the elastic modulus measuring apparatus concerning this invention. It is a principal part top view of FIG. It is a principal part enlarged view of FIG. FIG. 4 is a plan view of FIG. 3. It is explanatory drawing of the optical measuring device shown in FIG. It is principal part explanatory drawing of the conventional elasticity modulus measuring apparatus.

Explanation of symbols

S Test piece 10 Upper jaw part 12 Lower jaw part 14 Upper arm part 16 Lower arm part 18 Post 20 Displacement measuring part 20a Optical measuring instrument 20b Mechanical measuring instrument 22 Base 24 Ellipse rod

Claims (6)

Upper and lower jaws holding both ends of the test piece,
An upper and lower arm portion for sandwiching the central portion of the test piece in the longitudinal direction with a predetermined interval in the vertical direction;
A post that supports the upper and lower arm portions to be movable up and down;
An elastic modulus measuring apparatus comprising: a displacement measuring unit that measures a displacement amount of the clamping position of the upper and lower arm portions with respect to the test piece when a load is applied to the test piece via the upper and lower jaw portions. In
The displacement measurement unit converts the displacement amount into a transmission amount of a parallel light beam and detects the optical measurement device,
An elastic modulus measuring apparatus comprising: a mechanical measuring device that detects the amount of displacement by converting the amount of displacement into a moving amount in which the upper and lower arm portions move up and down along the post. The optical measuring instrument includes a projecting part and a light receiving part of the parallel light beams arranged to face each other, and a light shielding plate attached to each of the upper and lower arm parts is arranged between the projecting part and the light receiving part. The elastic modulus measuring apparatus according to claim 1. 3. The elastic modulus measuring apparatus according to claim 2, wherein the projection unit, the light receiving unit, and the light shielding plate have an air pipe that ejects air to a front surface thereof. 2. The elastic modulus measuring apparatus according to claim 1, wherein the mechanical measuring instrument includes a rotary encoder that detects a moving amount in which the upper and lower arm portions move up and down. The upper and lower arm portions are provided with a pair of grippers that are spring-biased in a direction to always hold the test piece, and provided with an elliptical rod that opens and closes the grippers close to or apart from each other. The elastic modulus measuring apparatus according to claim 4. 6. The elastic modulus measuring apparatus according to claim 1, wherein the test piece is made of hard plastic.

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