JP2007183129A - Hardness meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hardness meter capable of measuring the measuring surface of a measuring target with high precision, without being affected by the surface state of the measuring surface. <P>SOLUTION: The hardness meter is constituted, by bringing the tip of a press needle into contact with the measuring surface of the measuring target to calculate the hardness of the measuring surface from the depth of the cavity formed in the measuring target and equipped with a fixing member 10 for holding the press needle fixing member 15 for holding the press needle 16 so as to move the same along the axial line of the press needle 16 and a pair of leaf springs 1a and 1b, arranged in opposed relationship at a definite interval so as to hold the fixing member 10. The leaf springs 1a and 1b have central spring parts 3 and both side spring parts 4a and 4b positioned on both sides of the central spring parts 3, and the center points 7 of the central spring parts 3 are fixed to the press needle fixing member 15, while the center points 8a and 8b of both side springs 4a and 4b are respectively fixed to the fixing member 10 and a pair of leaf springs 1a and 1b are arranged so that the straight lines passing the center points 7, 8a and 8b of the respective spring parts mutually form substantially 90°. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an industrial product such as rubber and plastics, not a hard material such as a metal material, and a hardness measuring instrument used in medical, health and food industries such as skin, muscle, fruit and food. In particular, the present invention relates to a contact-type hardness meter that performs measurement by bringing a push needle into contact with an object to be measured, and relates to a hardness meter provided with a mechanism that holds the push needle with a leaf spring.

  As a means for detecting the displacement of the push needle corresponding to the hardness measurement value, an electronic or digital type using an optical linear gauge is known (for example, see Patent Document 1). In addition, as a spring load device for the rubber hardness tester, a cantilever plate spring, a loop plate spring, or a plate spring in which two strip-shaped elongated plates are arranged in parallel is used. A method of detecting the displacement of the push needle by attaching a gauge and detecting the expansion and contraction of the surface of the leaf spring is also known (see, for example, Patent Documents 2 to 3).

  The method using the optical linear gauge of Patent Document 1 has the following structure. A spindle movable in one direction is provided, and a glass scale having a lattice is attached to the spindle. A fixed scale on which a lattice similar to the lattice on the previous glass scale is formed and a light receiving element are fixed to the body at a position facing the lattice on the glass scale, and the glass is opposed to the light receiving element. The light emitting element is fixed to the main body at a position across the scale. And, between the spindle and the main body, there is a structure in which a detent pin is attached so that the glass scale can be kept in a correct position with respect to the fixed scale.

  The method using a cantilever-shaped leaf spring or a loop-shaped leaf spring in Patent Document 2 has the following structure. One end of the support member is fixed to the main body, and a loop-shaped leaf spring is attached to the other end of the support member. A push needle is attached to the loop-shaped leaf spring, and the push needle is suspended from the main body via the loop leaf spring.

  A spring load mechanism using a strip-shaped leaf spring of a hardness meter in Patent Document 3 will be described with reference to FIG. A leaf spring 150 having a two-sided spring portion 150a and a central spring portion 150b formed by dividing two into three parallel long holes, a part of the both-side spring portion 150a of the leaf spring 150 being supported Attached to the member 151, two leaf springs 150 are arranged in parallel and in the same direction with a gap therebetween. A connecting member 152 is disposed on the surface of the central spring portion 150b between the two leaf springs. The connecting member 152 is fixed to the upper central spring portion 150b with a screw 156, and the lower central spring portion 150b is supported by a push needle. The push needle 154 is attached to one end surface of the push needle support member 153 that is fixed by the member 153. And the fixing member 155 is attached to the upper surface of the both-side spring part 150a of the upper leaf | plate spring 150, and a part of fixing member 155 is fixed to the hardness meter main body which is not shown in figure. And the strain gauge 160 is stuck on the central spring part 150b of the leaf | plate spring 150, and it has the structure which calculates | requires the displacement of a push needle by detecting the expansion-contraction of the central spring part 150b surface.

JP 61-4942 (Page 7, FIG. 3) JP-A-1-284734 (6th page, FIG. 3) JP 2001-50882 (5th page, FIG. 2)

The method using the optical linear gauge disclosed in Patent Document 1 requires a spindle that moves in a fixed direction as a movable part for detecting displacement, and a bearing that holds the spindle, and further moves the linear gauge that detects the displacement of the spindle. A detent pin or the like for holding the side glass scale in the correct position is also required. All of them come into contact with a fixed part such as a main body case in a sliding or meshing manner, and eventually wear due to friction during operation.

  For this reason, not only the rattling and displacement detection errors due to the wear itself, but also the frictional force increases significantly due to contamination, and this frictional force causes the force of the spring load device of the hardness meter connected to the spindle to be applied to the tip of the needle. A large error is generated in the force at the tip of the push needle which is not transmitted and should deform the object to be measured.

  On the other hand, in the structure in which the push needle is suspended from the cantilever-shaped leaf spring or the loop-like leaf spring of Patent Document 2, there is no problem of friction and wear. Since it is not restrained, the tip of the push needle moves in the lateral direction fairly freely. Furthermore, with a cantilever-shaped leaf spring, even when only a vertical upward force is applied to the tip of the push needle, the tip moves in an arc shape, so that it moves in the horizontal direction simultaneously with the up and down movement, and the push needle The tip surface is inclined. Such behavior deviates from the original movement of the hardness meter, resulting in measurement errors.

  Further, in the structure in which the leaf spring in which two strip-shaped elongated plates of Patent Document 3 are arranged in parallel is arranged perpendicular to the axis of the push needle, the behavior of the push needle described above can be suppressed, but the measurement object The resistance against the action of the lateral force caused by the shape of the contact surface of the push needle will differ depending on the direction of the action. Therefore, when the object to be measured is rotated with respect to the measuring instrument with reference to the measurement point, and the same part is measured, strictly speaking, a difference occurs in the hardness value of the object to be measured.

  In the various leaf spring structures described above, a strain gauge is attached to the flat surface of the leaf spring, and the displacement of the push needle is obtained by capturing the amount of deflection of the leaf spring deformed according to the position of the push needle with the strain gauge. In the configuration, even if a slight lateral force acts on the tip of the push needle, the surface of the leaf spring is distorted, and the strain gauge detects this without distinguishing it from the strain caused by the vertical displacement of the tip of the push needle. . Further, since the displacement of the push needle is indirectly obtained from the amount of distortion caused by the bending of the leaf spring, it becomes a measurement error.

  From the above, in the method using the optical linear gauge as described above, there is a problem that a displacement detection error due to friction and wear of the mechanism portion occurs, resulting in a measurement error. In the method using a cantilever-like plate spring or a loop-like plate spring, an error due to the lateral movement of the tip of the push needle occurs, and in this case, there is a problem that an error in measurement occurs. In addition, in the method in which a leaf spring in which two strip-shaped elongated plates are arranged in parallel is arranged perpendicular to the axis of the push needle, the resistance to the action of the lateral force differs depending on the direction of the action, in this case However, there is a problem that an error in measurement occurs.

  An object of the present invention is to solve the above-described problems of the prior art and to provide a hardness meter capable of measuring with high accuracy without being affected by the surface state of the measurement surface of the object to be measured.

In order to solve the above problems and achieve the object, a hardness meter according to the present invention includes a push needle, a push needle fixing member that holds the push needle, and the push needle fixing member along the push needle axis. A fixed member that is movably held, a pair of leaf springs that are opposed to each other with a fixed interval across the fixed member, and a position detection that is disposed between the pair of leaf springs to detect displacement of the push needle A hardness meter that obtains the hardness of the object to be measured based on the displacement of the position detection unit caused by the relative position change between the push needle and the object to be measured. The leaf spring has a center spring portion and both side spring portions located on both sides of the center spring portion, the center point of the center spring portion is fixed to the push needle fixing member, and the center point of the both side springs is fixed to the fixing member. Each pair of leaf springs is fixed so that the straight lines passing through the center point of each spring portion form approximately 90 degrees with each other. And it is characterized in that it is location.

  With this configuration, the pair of leaf springs has strong rigidity against the force from the lateral direction perpendicular to the axial direction of the push needle without using a sliding position holding means such as a bearing or a guide mechanism. Acting as a member, there is almost no lateral movement of the tip of the push needle. Furthermore, the resistance against the action of the lateral force generated by the shape of the contact surface of the push needle of the object to be measured has at least the same resistance against the action from the four directions where the support points of the leaf springs are present. become. As a result, it is possible to provide a highly accurate hardness meter free from measurement errors.

  And since it can give from a very small load to the needle axis direction, an accurate and reproducible measurement result can be obtained.

  Further, the position detection unit is located on or near the needle axis, and is provided at a substantially central position between the pair of leaf springs.

  With this configuration, when the push needle receives a lateral force, the push needle and the link member connected to the push needle are moved based on the center position between the pair of leaf springs. Variation in the horizontal direction is minimized. As a result, it is possible to provide a highly accurate hardness meter with little measurement error.

  The position detection unit is a magnetoelectric conversion type using a differential transformer or a Hall element.

  With this configuration, since the displacement amount of the push needle in the axial direction can be directly obtained, a highly accurate hardness meter with little measurement error can be provided.

  According to the present invention, a pair of leaf springs has a strong rigidity against a force from a lateral direction perpendicular to the axial direction of the push needle without using a sliding position holding means such as a bearing or a guide mechanism. It works as a holding member, and there is almost no lateral movement of the tip of the push needle. As a result, it is possible to provide a hardness meter that can measure with high accuracy without any measurement error.

  Exemplary embodiments of a hardness meter according to the present invention will be described below in detail with reference to the accompanying drawings. 1, 2, and 3 are diagrams showing a hardness meter in the first embodiment of the present invention, and FIG. 4 is a diagram showing the hardness meter in the second embodiment. Note that, in the following description of the embodiment and the accompanying drawings, the same reference numerals are given to the same components, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a perspective view showing a spring load mechanism of a hardness meter in the present embodiment, FIG. 2 is an exploded perspective view showing a spring load mechanism of the hardness meter in the present embodiment, and FIG. 3 is a diagram of the hardness meter in the present embodiment. FIG. 3A is a plan view, FIG. 3B is a view showing a side surface and a deformed state of the leaf spring. FIG. As shown in FIGS. 1 and 2, the spring load mechanism of the hardness meter according to the present embodiment includes a push needle 16, a push needle fixing member 15 that holds the push needle 16, and a push needle fixing member 15. Are disposed between the pair of leaf springs 1a and 1b, the pair of leaf springs 1a and 1b, which are arranged to be opposed to each other with a fixed gap therebetween. And a position detector 20 for detecting the displacement of the push needle 16. Each of the pair of leaf springs 1a and 1b has a central spring portion 3 and both spring portions 4a and 4b located on both sides of the central spring portion 3, and the central point 7 of the central spring portion 3 is pushed through the link member 13. It is fixed to the needle fixing member 15, and the center points 8 a and 8 b of the springs 4 a and 4 b are respectively fixed to the fixing member 10 via the support member 11. Further, the pair of leaf springs 1a and 1b are arranged such that the straight lines A and B passing through the center points 7, 8a and 8b of the spring portions 3, 4a and 4b form approximately 90 degrees. The thus configured spring load mechanism is built in and fixed to a hardness meter body (not shown) and operates as a hardness meter. The hardness meter in the present embodiment makes the tip of the push needle 16 contact the object to be measured, and determines the hardness of the object to be measured based on the displacement of the position detection unit 20 due to the relative position change between the push needle 16 and the object to be measured. It is what you want.

  Next, the shape and deformation of the leaf spring used for the spring load mechanism in the hardness meter of this embodiment will be described. The leaf spring 1a and the leaf spring 1b have the same shape and will be described together. As shown in FIG. 3, the leaf springs 1a and 1b are thin plates and have a rectangular shape, and have a pair of symmetrically arranged long holes 2a and 2b extending in parallel with the longitudinal direction thereof. A central spring part 3 and two side spring parts 4a and 4b, which are divided into three parts at the long holes 2a and 2b, are formed. The central spring portion 3 is provided between the pair of long holes 2a and 2b, the double-side spring portions 4a are provided outside the long holes 2a, and the double-side spring portions 4b are provided outside the long holes 2b. Further, a fixing hole 5 is formed at the position of the center point 7 of the center spring part 3, and fixing holes 6a and 6b are formed at the positions of the center points 8a and 8b of the both side spring parts 4a and 4b, respectively. ing.

  Next, the deformation | transformation state of the leaf | plate springs 1a and 1b formed in this way is demonstrated. The center points 8a and 8b of the two springs 4a and 4b of the leaf springs 1a and 1b are fixed points, the center point 7 of the center spring part 3 is a movable point, and the center point 7 of the center spring part 3 is shown in FIG. When a force in the direction of the arrow is applied as shown in b), deformation as shown by the alternate long and short dash line occurs. When a force is applied in the direction of arrow C, the two side spring portions 4a and 4b have a shape in which the planes at both ends in the longitudinal direction are curved in the direction of arrow C with the center points 8a and 8b as the base points. The portion 3 has a shape curved in a convex shape with the center point 7 as a vertex with the planes at both ends in the longitudinal direction as the base point. On the other hand, when a force is applied in the direction of arrow D, the two side spring portions 4a, 4b have a shape in which the planes at both ends in the longitudinal direction are curved in the direction of arrow D with the center points 8a, 8b as the base points. The central spring portion 3 has a concave curved shape with the plane at both ends in the longitudinal direction as the base point and the center point 7 as the bottom point.

  The fixing member 10 is formed into a flat rectangular shape with chamfered corners at four corners and provided with a hole 21 at the center, and is equidistant at 90 ° intervals on the circumference with the hole 21 as the center. Four female screw portions 22 are formed. A male screw formed on one end surface of the support member 11 is engaged with the female screw 22 of the fixing member 10, and the support member 11 is based on the center position of each of the two planes of the fixing member 10. Are attached to the same line. A screw 12 is attached to the female screw portion formed on the other end surface of the support member 11 through the holes 6a and 6b of the plate springs 1a and 1b, and the plate springs 1a and 1b are fixed to the support member 11.

  A link member 13 for connecting the leaf springs 1a and 1b to each other is disposed in the hole 21 provided at the center position of the fixing member 10, and an adjustment member 25 is provided at one end of the link member 13. A male screw is formed. The male screw portion is passed through the hole 5 of the central spring portion 3 of one leaf spring 1a, and the one leaf spring 1a and one end of the link member 13 are engaged and fixed by a nut 14. A core support member 23 is provided at the other end of the link member 13, and a female screw is formed on the core support member 23. A male thread portion is formed at one end of the push needle support member 15. The male screw portion of the push needle support member 15 is passed through the hole 5 of the other leaf spring 1b and engaged with and fixed to the female screw portion of the core support member 23. In this way, the link member 13 is attached perpendicularly to the plane of the leaf springs 1a and 1b, and is configured such that the two leaf springs 1a and 1b co-operate.

The position detector 20 is provided at a substantially equal distance from the one leaf spring 1a and the other leaf spring 1b. The passive portion of the position detector 20 is attached to the fixed member 10, and the position detector 20 is provided. The active part is arranged at a position corresponding to the passive part of the position detector 20 on the link member 13 and interlocked with the movement of the push needle 16.

  The outer cylinder portion of the position detector 20 is attached to a hole 21 formed at the center of the fixing member 10 by adhesion. The passive part of the position detector 20 incorporates two coils 20a that form a differential transformer. When the core 20b moves in an excited state in which an AC voltage is applied from a circuit unit (not shown), the reactance of the two coils 20a changes, and the two coils 20a of the differential transformer change according to the amount of movement of the core 20b. A voltage is obtained.

  The push needle support member 15 is arranged in a vertical direction with respect to the plane of the fixing member 10, and one end portion of the push needle fixing member 15 is fixed to the core support member 23 with the other leaf spring 1b interposed therebetween, and the other end. A push needle 16 that contacts the object to be measured is detachably attached to the portion. The push needle 16 can be replaced with an optimum one according to the shape and hardness of the object to be measured (not shown).

  A core 20 b and a core fixing member 24 are disposed between the adjustment member 25 and the core support member 23 provided on the link member 13. A recess (not shown) provided on the opposite side of the female threaded portion of the core support member 23 is engaged with one end of the core 20b of magnetic material, and the core 20b is sandwiched between the core fixing member 24 and the core support member 23. Fixed. Further, the core fixing member 24 is coupled to the adjustment member 25 by screws formed respectively. The link member 13 is formed by the core 20 b, the core support member 23, the core fixing member 24, and the adjustment member 25 that are combined in this manner.

  In this way, the leaf springs 1a and 1b are firmly connected by the link member 13, the force applied to the push needle 16 is efficiently transmitted, and repeated and stable measurements are possible.

  With this configuration, the leaf springs 1a and 1b can be deformed in a large displacement amount with a low spring constant in the axial direction of the push needle 16, and can operate along the axial direction of the push needle 16 to achieve a lateral force. In contrast, the flat surfaces of the spring portions of the leaf springs 1a and 1b work as members having strong rigidity, and without using sliding position holding means such as bearings or guide mechanisms, It can be applied from a small load, and accurate and reproducible measurement results can be obtained.

  Further, the displacement amount of the push needle 16 in the axial direction can be directly obtained. Further, when the push needle 16 receives a lateral force, the push needle 16 and the link member 13 connected to the push needle 16 are moved based on the positions of the substantially equal distances between the leaf springs 1a and 1b. The fluctuation in the vertical direction of the active part constituting 20 can be suppressed. As a result, it is possible to provide a highly accurate hardness meter free from measurement errors.

  As described above, the spring load mechanism in the first embodiment is built in and fixed to a hardness meter body (not shown) and operates as a hardness meter. When the tip of the push needle 16 is brought into contact with the surface of the object to be measured (not shown) and the hardness meter body is pushed down to the object to be measured by a predetermined distance, the pressing according to the hardness, that is, the depression of the surface of the object to be measured. The needle 16 is lifted relatively.

  Then, as shown in FIG. 3, the center spring part 3 and the two side spring parts 4a and 4b of the leaf springs 1a and 1b are bent, and the position detector 20 connected to the push needle 16 shown in FIG. Since the position of the core 20b which is an active part constituting the position is displaced with respect to the position of the coil 20a which is a passive part constituting the position detector 20, the output of the position detector 20 changes. The output is amplified in a suitable amplifier circuit and displayed as hardness on a suitable indicator.

(Second Embodiment)
FIG. 4 is a perspective view showing a second embodiment of the present invention. In the second embodiment, the position detection unit and the link member are different from the first embodiment. As shown in FIG. 4, a male screw is formed at one end of the support shaft 101 as a link member in the present embodiment, and the male screw portion of the support shaft 101 is connected to one end as in the first embodiment. One leaf spring 1a and one end of the support shaft 101 are engaged and fixed by a nut through a hole in the central spring portion of the leaf spring 1a. A female screw is formed at the other end of the support shaft 101, and the male screw portion formed at one end of the push needle support member 15 is passed through the hole of the other leaf spring 1b to receive the female screw of the support shaft 101. Engage with and fix the screw. In this way, the support shaft 101 is attached perpendicularly to the plane of the leaf springs 1a and 1b, and the two leaf springs 1a and 1b are configured to move together.

  The position detection unit 110 includes a hall element 100, a magnet 103, and a magnet holding member 102. The Hall element 100 is attached to a plane facing the leaf spring 1b of the fixing member 10 directly or via a holding member (not shown). The magnet holding member 102 is fixed to the support shaft 101, and a cylindrical magnet 103 is fixed to the magnet holding member 102. The magnet 103 is arranged such that its cylindrical central axis is parallel to the axial direction of the support shaft 101 and the cylindrical center of the magnet 103 and the detection unit center of the Hall element 100 are aligned. Further, the end surface of the magnet 103 on the Hall element 100 side and the end surface (mold surface) of the Hall element 100 are arranged to face each other with a certain gap.

  According to the position detection unit 110 configured in this way, the distance between the magnet 103 and the Hall element 100 changes due to the movement of the push needle 16 in the axial direction, and the change in the magnetic flux density with respect to the gap causes the change. Hall output voltage changes. By this change, the displacement amount of the push needle 16 can be directly detected. As a result, it is possible to provide a highly accurate hardness meter free from measurement errors.

  As described above, the spring load mechanism in the second embodiment is built in and fixed to a hardness meter main body (not shown) as in the first embodiment. When the tip of the push needle 16 is brought into contact with the surface of the object to be measured (not shown) and the hardness meter body is pushed down to the object to be measured by a predetermined distance, the pressing according to the hardness, that is, the depression of the surface of the object to be measured. The needle 16 is lifted relatively.

  Then, as shown in FIG. 3, the center spring portion 3 and the side spring portions 4a and 4b of the leaf springs 1a and 1b are bent, and the position detector 110 connected to the push needle 16 shown in FIG. Since the position of the magnet 103 which is an active part constituting the position is displaced with respect to the position of the Hall element 100 which is a passive part constituting the position detector 110, the output of the position detector 110 is changed. The output is amplified in a suitable amplifier circuit and displayed as hardness on a suitable indicator.

It is a perspective view which shows the hardness meter which is the 1st Embodiment of this invention. It is a disassembled perspective view which shows the hardness meter which is the 1st Embodiment of this invention. It is a 2nd view which shows the spring shape and deformation | transformation of the hardness meter of this invention. It is a perspective view which shows the hardness meter which is the 2nd Embodiment of this invention. It is a perspective view which shows the hardness meter of a prior art.

Explanation of symbols

1a, 1b Leaf spring 2a, 2b Long hole 3 Central spring part 4a, 4b Both-side spring part 5, 6a, 6b, 21 Hole 7, 8a, 8b Center point 10 Fixing member 11 Support member 12 Screw 13 Link member 14 Nut 15 Push Needle fixing member 16 Needles 20, 110 Position detector 20a Coil 20b Core 22 Female screw 23 Core support member 24 Core fixing member 25 Adjustment member 100 Hall element 101 Support shaft 102 Magnet holding member 103 Magnet

Claims (3)

A push needle, a push needle fixing member that holds the push needle, a fixing member that holds the push needle fixing member so as to be movable along the push needle axis, and a fixed interval across the fixing member A pair of leaf springs disposed; and a position detection unit disposed between the pair of leaf springs to detect displacement of the push needle, wherein the tip of the push needle is brought into contact with an object to be measured; A hardness meter that obtains the hardness of the object to be measured based on the displacement of the position detection unit due to a relative position change with the object to be measured, wherein the leaf spring is positioned on both sides of the central spring part and the central spring part. A center point of the central spring part is fixed to the push needle fixing member, a center point of the both side springs is fixed to the fixing member, and the pair of leaf springs The straight lines passing through the center point of the spring part are arranged so as to form approximately 90 degrees with each other. Hardness meter that. 2. The hardness meter according to claim 1, wherein the position detection is located on or near the push needle axis and is provided at a substantially central position between the pair of leaf springs. 3. The hardness meter according to claim 1, wherein the position detection is a magnetoelectric conversion type using a differential transformer or a hall element.

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