JP4064011B2 - Rubber hardness tester with improved spring loading mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber hardness tester having an improved spring load mechanism.
[0002]
[Prior art]
In the rubber hardness tester (durometer) defined by JISK6253 etc., as a means for detecting the needle displacement corresponding to the hardness measurement value, a mechanical type is generally a displacement enlargement mechanism using a dial gauge mechanism. There are known electronic and digital types using an optical linear gauge (Japanese Patent Laid-Open Nos. 60-102540 and 61-4942). In addition, a cantilever-shaped leaf spring or loop-shaped leaf spring is used as a spring load device for the rubber hardness tester, and a strain gauge is attached to the surface of the leaf spring to detect expansion and contraction of the leaf spring surface. A method for detecting the displacement of the lens is also known (Japanese Patent Laid-Open No. 1-284734).
[0003]
However, in the method using the dial gauge mechanism or the optical linear gauge as described above, a displacement detection error due to friction or wear of the mechanism portion occurs, and a cantilever-like leaf spring or a loop-like leaf spring is used. In the system, there is a problem that an error occurs due to the lateral movement of the needle tip.
[0004]
First, the method using a dial gauge mechanism requires a spindle that moves in a certain direction as a movable part for detecting displacement, and a bearing that holds the spindle, and a rack for transmitting the displacement of the spindle to the enlargement mechanism. A pinion mechanism and a detent pin for the mechanism are also required. All of them come into contact with fixed parts such as the main body case in a sliding or meshing manner, and eventually wear due to friction during operation.Therefore, not only the rattling and displacement detection error due to the wear itself but also the frictional force significantly increases due to fouling. Due to this frictional force, the force of the spring load device of the hardness meter connected to the spindle is not transmitted to the tip of the push needle, and a large error occurs in the force at the tip of the push needle to deform the sample.
[0005]
Even with an optical linear gauge, it is necessary to have a non-rotating pin for holding the glass scale on the moving side of the linear gauge in the correct position along with the spindle bearing. The same error cause and malfunction will be caused.
[0006]
On the other hand, in the method of measuring displacement by attaching a strain gauge to a cantilever leaf spring or loop leaf spring, there is no bearing or rubbing portion from the fixed part to the tip of the push needle, and there is a problem of friction and wear. In either case, since the push needles are suspended from the fixed portion without being restrained in the middle, so to speak, the tip moves considerably freely in the lateral direction. Such an operating state not only deviates from the original movement as a hardness tester specified by JISK6253, etc., but 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 as a displacement without distinguishing it from the distortion caused by the vertical displacement of the tip of the push needle.
[0007]
In addition, 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 also deviates from the original movement of the hardness meter, resulting in measurement errors.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a spring load mechanism that does not cause mechanical contact and accompanying friction between the push needle, the movable part connected thereto, and the fixed part, and that the tip of the push needle does not swing laterally. A rubber hardness meter having a displacement detection mechanism is provided.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the rubber hardness tester according to the present invention has a proximal end portion of a spring load mechanism in which a tip of a push needle is vertically applied to a rubber surface and the push needle is supported directly or indirectly by a free end. In a rubber hardness meter in which the rubber hardness is determined from the depth of the depression generated in the rubber surface by the tip of the push needle when the rubber surface is brought close to the rubber surface by a predetermined distance,
Two positions retreated backward by a first and second distances along the axis of the push needle from the tip of the push needle itself or the push needle support member are used for the push needle by the free end of the spring load mechanism. The first and second support positions of
The spring load mechanism is a leaf spring having a rectangular main portion, and has a pair of elongated holes that form symmetrically arranged slits extending along and parallel to both sides of the leaf spring, thereby separating the spring portions on both sides and the center spring portion. The two leaf springs thus divided are maintained in parallel at an interval corresponding to the interval between the first and second support positions for the push needle, and each intermediate position of the spring portions on both sides of each leaf spring One of the intermediate positions of the central spring portion is fixed to the rubber hardness tester main body as the base end portion of the spring load mechanism, and the other intermediate position is used as the free end portion of the spring load mechanism for the push needle. The first and second support positions are joined to each other.
[0010]
In the above structure, the middle position between the two side spring parts or the central spring part of each leaf spring is a leaf spring element that can be displaced only in the vertical direction with respect to both ends of the spring parts. Since the leaf springs are connected to each other, the middle position of both sides or the central spring part, which is the free end of the spring load mechanism, is only in the up-down direction with respect to the middle position of the other spring part, which is the base end part. It can be displaced. That is, for the front / rear / right / left forces, the combined leaf springs work as a highly rigid member without using sliding position holding means such as bearings or guide mechanisms, There is almost no movement in the front / rear and left / right directions.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a planar shape of a leaf spring used in the spring load mechanism of the present invention. A leaf spring 1 formed from a substantially strip-like elongated leaf spring piece is provided along both sides 2 and 2 thereof. It has a pair of long holes 3 symmetrically arranged extending in parallel. The long hole 3 forms a slit that divides both the spring portions 4 and the central spring portion 5. Tabs 6 are continuously provided at the intermediate positions of the side edges 2 and 2, and a margin hole 7 for attachment is formed at the center of the intermediate square area on both sides of the leaf spring 1 including the periphery of these tabs on the three sides. . A margin hole 8 for attachment is also formed at an intermediate position of the central spring portion 5. After all, the shape of the leaf spring 1 is finished symmetrically in the front-rear and left-right directions with the allowance hole 8 of the central spring portion 5 as the center.
[0012]
FIG. 2 shows a structure in which two plate springs are connected to a push needle as a spring load mechanism as viewed from three sides. In this case, the leaf springs 1a and 1b are held by the corresponding spacers with their both side spring portions and the central spring portion spaced apart from each other in the vertical direction. Each of these spacers forms part of the both-side holding member 9 and the center holding member 10. As is apparent in FIG. 2C, the both-side holding members 9 are composed of an upper yoke 9a, a pair of spacers 9b, and a square washer 9c, and a leaf spring between both leg portions of the upper yoke 9a and the upper end surfaces of the pair of spacers 9b. The intermediate portions on both sides of 1a are sandwiched, and the intermediate portions on both sides of the leaf spring 1b are sandwiched between the lower end surfaces of the pair of spacers 9b and the square washer 9c. In the through screw hole of both legs of the yoke 9a and the through margin hole of the spacer 9b, the upper mounting bolt 11a and the lower mounting bolt 11b are inserted from above and below, respectively, and the above-described margin spring 7 (FIG. 1) of the leaf spring is inserted. These leaf springs 1a and 1b are held in parallel at equal intervals by being penetrated.
[0013]
2B and C, the central holding member 10 is composed of an upper washer 10a, a central spacer 10b, and a square nut 10c. The central portion of the leaf spring 1a is interposed between the upper washer 10a and the upper end surface of the central spacer 10b. Further, the center portion of the leaf spring 1b is sandwiched between the lower end surface of the spacer 10b and the square nut 10c. The central holding member 10 is fixed together with the leaf springs 1a and 1b by inserting a long bolt 12 from above into the through margin hole of the spacer 10b and the square nut 10c through the upper washer 10a. As can be understood from FIG. 2B, both sides are formed in the square nut 10c, and the back surface (nut lower end surface) 10e is always inside the lower end shaft hole 13 of the hardness meter casing partially shown in FIG. It comes into contact with and is supported by the hole edge.
[0014]
The upper part of the pusher joint pipe 14 having an inner peripheral screw engages with a relatively long tip of the long bolt 12 protruding from below the square nut 10c. The joint pipe 14 passes through the lower end shaft hole portion 13 described above, and the lower end portion thereof occupies a position corresponding substantially to the lowermost end portion (not shown) of the hardness meter casing. In the joint pipe 14, a main body screw portion 15 a of the push needle 15 is inserted and fixed to an inner peripheral screw of the long screw 12 or less, and a nut 16 is provided at the tip of the screw portion 15 a on the push needle side exposed from the lower end of the joint pipe 14. Are engaged to fasten the engaged state with the joint pipe 14. Thus, the central holding member 10, the long bolt 12, the joint pipe 14, and the nut 16 together constitute a support member for the push needle 15. The position between the washer 10a / spacer 10b in the central holding member 10 is the first support position for the push needle by the free end portion of the leaf spring 1a that is retracted by the first distance in the axial direction from the push needle tip. The position between the spacer 10b and the square nut 16 becomes the second support position for the push needle by the free end portion of the leaf spring 1b that is retracted by the second distance in the axial direction from the tip of the push needle.
[0015]
The spring load mechanism including the leaf springs 1a and 1b and the center holding member 10 holding the push needle 15 via the both-side holding member 9 and the joint tube 14 is the center holding member in a steady state where the leaf springs 1a and 1b are flat. Ten square nuts 10c are in contact with and supported by the lower end shaft hole 13 of the hardness tester casing, so that downward movement of the member 10, and hence downward convex curvature of the central spring portion 5 of the leaf spring does not occur. However, when the push needle 15 is pressed upward against the hardness meter casing, and thus the both side holding members 9, as shown by phantom lines in FIG. 2B, it is left to the center of the leaf springs 1a and 1b. It does not prevent the upward convex curve of the spring portion 5 and therefore the push needle 15 from being lifted relatively. The upward convex curve of the central spring portion 5 is generated while lifting both ends of the leaf spring, which is a connection portion with the both-side spring portions 4, so that the spring portion 4 generates an upwardly concave curvature, but each leaf spring 1a, As a result of the one-sided nature of 1b and the vertical arrangement, there is almost no lateral distortion.
[0016]
3-5 is a figure which shows the upper surface of the hardness meter casing which accommodated the spring load mechanism mentioned above, a side surface, and a cross section, respectively, combining a fracture surface or a half section. The casing body 17 has a rectangular parallelepiped box shape having an indoor width and depth corresponding to the width of the both-side holding member 9 and an indoor length corresponding to the length of the leaf springs 1a and 1b. The cover 18 holding both the leg portions of the yoke 9a of the holding member is covered, and this is fixedly held by the side edge bolts 19 (FIG. 3), whereby the whole spring load mechanism is accommodated and held.
[0017]
The lower end shaft hole portion 13 of the casing described above is centrally held at the main body portion screwed from below into the through screw hole 20 of the large boss portion 17b protruding downward from the central portion of the bottom plate portion 17a of the casing main body, and at the screw tip end side. A small boss portion 13a that supports the square nut 10c of the member 10, and a screw block having an outer diameter reduced portion 13b that protrudes downward in a range substantially corresponding to the thickness of the large boss portion 17b from the screwed rear end side, By adjusting the screwing position, bias deflection is applied to the leaf springs 1a and 1b, and an initial load applied to the push needle 15 is set. However, the state shown in FIGS. 4 and 5 is a zero bias state in which the central spring part 5 of the leaf springs 1a and 1b supported by the central holding member 10 is maintained in the same horizontal plane as the both side spring parts 4 and 4. The initial load on the push needle 15 is zero.
[0018]
An annular space having a sufficient thickness is formed between the outer periphery of the outer diameter reducing portion 13b and the inner periphery (thread surface) of the through screw hole 20, and the plug head having a hollow portion 21a on the inner periphery of the through screw hole 20 The outer peripheral screw 21b at the distal end of the screw 21 is screw-engaged, and the outer periphery of the outer diameter reducing portion 13b corresponds to the inner peripheral surface forming the hollow portion 21a of the plug head 21 with a margin. At the center of the lower end surface portion of the plug head 21, there is a central hole that allows the push needle 15 and the screw portion 15 a to be arranged and passed, and the nut 16 that fastens the screw portion 15 a is located in the hollow portion 21 a of the plug head 21. .
[0019]
As is clear from FIG. 3 in particular, for example, in the central spring portion 5 of the leaf spring 1a, the strain gauge 22 is attached at a position slightly shifted to the right side from the middle in the longitudinal direction (spring load mechanism attachment position). Since the amount of deflection of the leaf spring and the distortion of each surface are proportional to each position, the strain gauge position may be anywhere as long as it causes deflection displacement. As described above, the parallel maintaining action of the two leaf springs 1a and 1b However, when there is a possibility that a strong lateral force acts on the tip of the push needle 15 and the surface of the leaf spring may be distorted, two, four, six, etc. When the strain gauges are arranged on the leaf springs in the front-rear and left-right directions, the lateral components of the outputs of these strain gauges cancel each other, and the influence on the error can be suppressed to a minute. There are various types of displacement measuring means other than strain gauges. For example, there is an eddy-electric sensor as a non-contact displacement measuring means.
[0020]
The lower leaf spring 1b is provided with a spring constant adjusting mechanism 23 having two adjustable upper and lower bridging plates that intersect with the leaf spring within a range in which the slit 3 exists. It is fixed with the leaf spring 1b interposed therebetween. When the spring constant adjusting mechanism 23 is fastened and fixed, the leaf spring does not bend outside the mechanism and exhibits a different spring constant depending on its position. Although not shown, a similar adjustment mechanism should be arranged on the left side of the hardness meter shown in FIGS. 3 and 4 to adjust symmetrically.
[0021]
In the hardness meter of the embodiment described above, when the tip of the push needle 15 is vertically applied to the surface of the rubber to be tested (not shown) and the plug head 21 is pushed down until it touches the rubber surface, the rubber hardness, That is, the push needle 15 is relatively lifted according to the depth of the depression on the rubber surface, and the leaf springs 1a and 1b are bent as shown in FIG. 2, and the output of the strain gauge 22 corresponding to the bending is appropriate. Amplified in the amplifier circuit and displayed as rubber hardness on a suitable indicator.
[0022]
【The invention's effect】
As described above, according to the present invention, an improved spring load mechanism mainly composed of two leaf springs is used, there is no mechanical contact between the movable part and the fixed part and the accompanying friction, and the push needle A rubber hardness tester whose tip does not swing laterally is provided.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a planar shape of a leaf spring used in a rubber hardness meter of the present invention.
2A is a plan view showing an embodiment of the spring load mechanism of the present invention using two leaf springs of FIG. 1, FIG. 2B is a longitudinal cross section, and FIG. It is.
FIG. 3 is a plan view including a partial fracture and a cross section of a rubber hardness meter including a spring load mechanism of the present invention.
4 is a side view including a partially broken and vertical cross section of the rubber hardness tester shown in FIG. 3;
5 is a cross-sectional view in which the left half is a cross section taken along the line AA in FIG. 4 and the right half is a cross section taken along the line BB in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Leaf spring 3 Long hole 4 Both-side spring part 5 Central spring part 6 Tab 7, 8 Margin hole 9 Both-side holding member 10 Central holding member 9a Upper yoke 9b Spacer 9c Square washer 11a Upper attachment bolt 11a
11b Lower mounting bolt 11b
12 Long bolt 12
13 Lower end shaft hole portion 14 Needle joint tube 15 Needle 16 Nut 17 Casing body 18 Lid 21 Plug head 22 Strain gauge 23 Spring constant adjustment mechanism

Claims (1)

When the tip end of the push needle is vertically applied to the rubber surface and the base end portion of the spring load mechanism supporting the push needle directly or indirectly at the free end is brought close to the rubber surface by a predetermined distance, the push needle In the rubber hardness tester, where the rubber hardness is determined from the depth of the depression generated on the rubber surface by the tip of
Two positions retreated backward by a first and second distances along the axis of the push needle from the tip of the push needle itself or the push needle support member are used for the push needle by the free end of the spring load mechanism. The first and second support positions of
The spring load mechanism is a leaf spring having a rectangular main portion, and has a pair of elongated holes that form symmetrically arranged slits extending along and parallel to both sides of the leaf spring, thereby separating the spring portions on both sides and the center spring portion. The two leaf springs thus divided are maintained in parallel at an interval corresponding to the interval between the first and second support positions for the push needle, and each intermediate position of the spring portions on both sides of each leaf spring One of the intermediate positions of the central spring portion is fixed to the rubber hardness tester main body as the base end portion of the spring load mechanism, and the other intermediate position is used as the free end portion of the spring load mechanism for the push needle. A rubber hardness tester bonded to each of the first and second support positions.

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