JPH06313752A - Hardness tester for soft material - Google Patents

Abstract

PURPOSE:To simplify structure and at the same time increase the accuracy for measuring the hardness of a soft material. CONSTITUTION:The title tester is provided with a press member 6 for surrounding a measuring terminal 5 for detecting stress by pressing the measuring terminal 5 to a surface 4 to be measured and a hardness meter body 7 for maintaining the press member 6 and the measuring terminal 5 so that they can move freely in axial direction and at the same time for providing them so that they are flexible. Also, it is provided with a signal transmitter 8 for outputting a hold signal when the press member 6 is pressed to the surface 4 to be measured by a specific amount of press force and a load cell 9 for measuring stress which the measuring terminal 5 receives at the time of transmission of hold signal when the press member 6 and the measuring terminal 5 are pressed to the surface 4 to be measured by a specific press force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hardness tester for a soft material, which objectively measures the local hardness of a living body and the softness of electronic equipment, construction materials, furniture, clothes, foods and the like.

[0002]

2. Description of the Related Art Currently, a vulcanized rubber physical test method (J
IS K 6301) and plastic durometer hardness test method (JIS K 7215) are applied. The tester used in these test methods, when the pressure surface is brought into contact with the surface to be measured, the distance by which the push needle protruding by the spring pressure from the center hole of the pressure surface is pushed back by the elasticity of the surface to be measured, It uses a quantitative hardness method.

The hardness tester based on these test methods is
For example, as shown in FIG. 6, the measurement terminal d, which is always prone to be projected by the spring c in the hardness meter body b, on the fixed surface a.
Is elastically contacted by a guide portion e, and an indicator h is attached via a transmission piece such as a rack f or a pinion g associated with the measuring terminal d.
Is used to measure the rubber hardness H. That is, when the diameter of the measuring terminal d is about 1 mm, the initial load is 55 g (H = 0), the stroke is 2.54 mm, the final load is 855 g (H = 100), and the spring constant of the spring c is 3.15 Kg / cm, H = 100 x (L-X)
/ L (see Table 1). (However, L: Stroke X: Length pushed into measured surface a)

[0004]

[Table 1] Then, the hardness meter is held vertically, the measurement terminal d is contacted so that the measurement terminal d is perpendicular to the surface a to be measured, and the hardness meter is immediately read in an analog manner.

The JIS standard is simple in this way, and there are very few prescribed conditions for both the test method and the tester, and the test methods vary greatly depending on the tester, which is very accurate and highly objective, and the reproducibility is high. There was the inconvenience that a high test result could not be obtained.

[0006] Japanese Patent Publication No. 55-38621 and Japanese Patent Publication No. 56-50575 are known to solve the above disadvantages. These publicly known examples include a measurement terminal that contacts the surface to be measured of the soft material and a pressure member that surrounds the measurement terminal, and both the measurement terminal and the pressure member are supported on the hardness tester main body by a spring. Then, these measuring terminals and the pressing member are pressed against the surface to be measured, the pressing force between these measuring terminals and the pressing member is electrically taken out, and the relative position change between the measuring terminal and the pressing member due to the pressing is changed. It is intended to read out the hardness with high accuracy by taking it out electrically and finally making it easy to measure and free from measurement blur.

[0007]

However, in any of the above-mentioned known examples, the change in the relative position between the measuring terminal and the pressing member together with the pressing force is an indispensable condition, which complicates data processing and results in simultaneous measurement. The error range becomes large. In other words, hardness meter for soft plastics (JI
SK 7215 A type), once as shown in Table 2,
The stroke of the measuring terminal is 2.54 mm (0.1 inch) divided into 100 equal parts. Therefore, once the moving distance of the measuring terminal is 2.54 mm (1/1000 inch). Therefore, the allowable error is ± 1 degree (load conversion ± 8 g).

[0008]

[Table 2] Therefore, the present invention has been made in view of the above circumstances,
An object of the present invention is to provide a hardness meter for a soft material, which has a simple structure and high measurement accuracy.

[0009]

In order to solve the above problems, the hardness meter for soft materials of the present invention is basically based on detecting the load amount on the horizontal axis of Table 2 using a pressure detector, for example, a load cell. , This is because a general load cell has an accuracy of (± 0.2%), and when used in the above hardness tester, simply measuring the value on the horizontal axis instead of the vertical axis in Table 2, By utilizing the fact that the detection accuracy is improved, the measurement terminal that presses against the surface to be measured to detect stress, the pressure member that surrounds the measurement terminal, and the pressure member and the measurement terminal are moved in the axial direction. A hardness meter main body that is freely held and installed elastically, a signal transmitter that outputs a hold signal when the pressure member is pressed against the surface to be measured by a predetermined amount, and the measurement is performed together with the pressure member on the surface to be measured. When the terminal is pressed a predetermined amount, the measurement is performed when the hold signal is transmitted. Those formed by and a pressure sensor that measures the stress receiving terminals.

Further, the measuring terminal is attachable to and detachable from the hardness meter main body, and the elastic force can be changed between the measuring terminal and the pressure member elastically mounted on the hardness meter main body.

[0011]

According to the hardness tester for soft material having the above-mentioned structure, when the hardness tester main body is held by fingers and the measurement terminal and the pressing member are pressed against the surface to be measured, these are elastically mounted on the hardness tester main body. Therefore, when it is compressed and reaches a predetermined pressing force, that is, when a natural plane of the surface to be measured is approximately obtained, the signal transmitter is activated to output a hold signal and the measurement terminal receives at that time. Stress is measured with a pressure detector,
The hardness of the surface to be measured is calculated from this measured value.

Further, since the measuring terminal is attachable / detachable to / from the hardness meter main body, the measuring terminal can be selected and attached to the hardness meter main body according to the property of the surface to be measured. Further, since the measuring terminal and the pressing member are elastically mounted on the hardness tester main body so that the elastic force can be changed, the measuring range can be expanded by adjusting the elastic force according to the property of the surface to be measured.

[0013]

Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a plan view in which a part of the hardness meter for soft material of the present invention is sectioned, FIG. 2 is a cross-sectional view of the hardness meter portion constituting the hardness meter for soft material of the present invention, and FIG. 3 is for soft material of the present invention. FIG. 4 is a plan view of the display unit that constitutes the hardness meter, and FIG. 4 is a side view of the display unit.
In the figure, reference numeral 1 represents a hardness meter for soft material of the present invention, and the hardness meter 1 for soft material comprises a hardness meter section 2 and a display section 3 electrically connected thereto. The hardness meter unit 2 has a measuring terminal 5 that is pressed against the surface to be measured 4 to detect stress, a pressure member 6 that surrounds the measuring terminal 5, an axial movement of the pressure member 6 and the measuring terminal 5. A hardness meter main body 7 which is freely held and elastically mounted, and a signal transmitter 8 which outputs a hold signal when the pressure member 6 is pressed against the surface 4 to be measured.
And a load cell 9 (pressure detector) that measures the stress received by the measurement terminal 5 when the hold signal is transmitted when the measurement terminal 5 is pressed against the surface to be measured 4 together with the pressure member 6. Become.

In the measuring terminal 5, a probe 13 having a curved front end surface 13a can be attached to and detached from one end of a spindle 12 which slides in a slide pipe 11 fixed in the hardness tester main body 7 via a fixing ring 10. It is screwed on. The probe 13 has various shapes depending on the surface 4 to be measured.

A probe spring 14 is interposed between the other end of the spindle 12 and the load cell 9 provided in the hardness tester main body 7 to urge the spindle 12 toward the probe 13 side. . That is, a spring stopper 15 is provided on the other end of the spindle 12, and a spring stopper 16 is further provided on the end surface of the load cell 9, and the probe spring 14 is fitted between these spring stoppers 15, 16. It does not come off. Further, a stopper ring 17 is fixed to the spindle 12, and when the stopper ring 17 is brought into contact with the fixed ring 10, the probe spring 14 prevents the probe 13 from protruding beyond a predetermined distance. The probe spring 14 has various elastic forces and can be replaced.

The pressure member 6 has a plurality of shafts 21 fixed to a pressure ring holder 20 that slides outside the slide pipe 11 inside the hardness tester main body 7, and these shafts 21 connect the hardness tester main body 7 to each other. Penetrates through these shafts 21
A pressure ring 22 is fixed to one end of the pressure ring.

A pressure ring spring is provided between the other end of the pressure ring holder 20 and the fixed ring 10.
The pressure ring holder 20 is urged toward the pressure ring 22 via the interposition of 23. That is, a spring stopper 24 is provided at the other end of the pressure ring holder 20, and further the fixing ring 10 is provided.
A spring stopper 25 is also provided on the end surface of the pressure ring spring 23.
It is fitted so that it will not come off. The pressure ring 22 is configured so as not to protrude beyond a predetermined distance by the pressure ring holder 20 contacting the inner end surface of the hardness tester main body 7 on the pressure ring 22 side. The pressure ring spring 23 has various elastic forces similarly to the probe spring 14 and can be replaced.

The hardness tester main body 7 has a cylindrical shape and is easily gripped by human fingers, and an electric constant pressure loader 50, which will be described later, is attached to the outer end surface on the opposite side of the probe 13. A screw hole 26 that can be used is dug.

The signal transmitter 8 includes a limit switch 30 attached to the fixed ring 10 and the pressing member 6.
And a stat 31 which is screwed to the shaft 21 of the probe and actuates the limit switch 30. The probe 13 and the pressure ring 22 are mounted on the surface to be measured 4 against the spring force of the probe spring 14 and the pressure ring spring 23. When the hardness is measured by pressing and holding, the limit switch 30 is turned on by hitting the stat 31 against the limit switch 30 and is taken out as a display hold signal.

In this signal transmitter 8, when the measured surface 2 is a curved surface, the pressure ring 22 is a spring for the pressure ring.
The surface to be measured 4 around the probe 13 is pushed to a constant pressure by the spring force of 23, and the pressure ring 22 is used as a temporary reference surface.
The position where the distortion due to is eliminated is detected, and the time point is taken out as the display hold signal. That is, the load cell 9 measures the load detected by the probe 13 via the spindle 12 and the probe spring 14, and outputs the load on the horizontal axis shown in Tables 1 and 2. Since the load cell 9 generally has an accuracy of ± 0.2%, in the example of Table 2, the accuracy is 822 g × ± 0.2% = ± 1.64 g, and the accuracy is ± 1.64 g / 8 g ≒ ± 0.21 degree.
Improves the accuracy (± 1 degree) of a general hardness tester. In addition,
Although the load cell is used in this embodiment, the present invention is not limited to this as long as the pressure can be detected.

The display unit 3 displays the hardness by obtaining information from the limit switch 30 and the load cell 9, and its display unit is Kg, g or N. When expressing the hardness as a change or degree of the length of the spring, the hardness is calculated based on the spring constant, which is the ratio of the load to the length, and displayed on the digital display surface 42 described later. The display section 3 receives and connects the cord 32 from the hardness tester section 2 through the input terminal 40. The display unit 3 is a digital force cage, which has a digital display surface 42 on the surface of the case 41, and a power switch 43 and a clear / hold switch 44 for turning on / off the digital display under the digital display surface 42. Furthermore, a zero switch is placed under the clear / hold switch 44.
There is 45, and it performs the zero reset of the digital display. In addition,
An AC adapter shank 46 for connecting a charging AC adapter and an output connector 47 for outputting an analog signal and a digital signal are provided on the side surface of the case 41. By connecting a recorder and a personal computer to the output connector 47, data recording and data processing are possible.

Next, a method of using the hardness meter 1 for soft material having the above-mentioned structure will be described. First, depending on the measurement purpose of the surface 4 to be measured, the probe terminal 14 and the pressure ring spring 23 of the pressure gauge 6 and the measurement terminal 5 of the hardness meter section 2 of the soft material hardness meter 1 are selected and selected appropriately. Further, the shape of the probe 13 is selected appropriately. Next, the stat 31 of the signal transmitter 8 is adjusted to determine a temporary reference plane in which the strain due to the pressure ring 22 is eliminated. Then, the power switch 43 of the display unit 3 is turned on to bring it to a steady state, and the clear / hold switch 44 is turned on. When the probe 13 of the measurement terminal 5 and the pressure ring 22 of the pressure member 6 at the tip of the hardness tester 2 are applied to the surface to be measured 4 and pushed, the probe 13 and the pressure ring 22 are connected to the spindle 12 and the pressing The stat of the signal transmitter 8 attached to the pressure ring holder 20 moves to the right side in FIG. 2 against the spring force of the probe spring 14 and the pressure ring spring 23 via the pressure ring holder 20. 31 hits the limit switch 30 to turn it on, and outputs a hold signal from the limit switch 30. At that time, the stress received by the probe 23 is
Measured by the load cell 9 via 12 and the probe spring 14, the information is sent to the display unit 3 and is calculated to display the hardness of the measured surface 4 on the digital display surface 42.

FIG. 5 shows an electric constant pressure loader, which is used together with the hardness meter 1 for a soft material of the present invention when more accurate measurement of the soft material is required. In this electric constant pressure load machine 50, an upper plate 53 and a lower plate 54 are laterally attached to a column 52 standing on a measuring stand 51, and a screw 55a is engraved between the upper plate 53 and the lower plate 54. A load bar 55 is provided, and a frame 56 penetrates between the upper plate 53 and the lower plate 54 in a vertically movable manner, and a weight steel 57 is mounted on the frame 56. Then, the load bar is placed between the upper and lower plates 53 and 54.
A moving arm 58 that is screwed to 55 but fixed to the frame 56 is provided, and a pulley 59 is attached to this load rod 55,
This pulley 59 and pulley 61 attached to the motor 60
Belt 62 is hung between and. The motor 60 is installed on the lower plate 54.

Electric constant pressure load machine constructed as described above
The hardness meter unit 2 of the hardness meter 1 for soft material of the present invention is attached to the lower end 56a of the frame 56 of 50. That is, the screw at the lower end 56a is screwed into the screw hole 26 of the hardness tester 2.

This electric constant pressure loader 50 is used, that is, the object to be tested is placed on the measuring table 51, the motor 60 is rotated at a constant speed, and the pulley 59 is rotated by the belt 62 to load the load bar.
Rotate 55. As a result, the moving arm 58 that meshes with the screw 55a of the load bar 55 moves downward, so that the frame 56 descends.
Since it comes into contact with and is further pressed, the hardness test can be performed on the same material under the same conditions. Therefore, a highly accurate measured value of the soft material can be obtained.

[0026]

As described above in detail, according to the hardness tester for soft material of the present invention, when the hardness tester main body is held by fingers and the measuring terminal and the pressing member are pressed against the surface to be measured, these Is elastically mounted on the body of the hardness tester, and when it is compressed and reaches a predetermined pressure, that is, when a natural plane of the measured surface is approximately obtained, the signal transmitter is activated and a hold signal is issued. The stress received by the measuring terminal at that time is measured by a pressure detector, and the hardness of the surface to be measured is calculated from this measured value. Therefore, since the structure is simplified, the weight and the size can be reduced, and at the same time, the cost can be reduced and the measurement accuracy can be improved.

Further, since the measuring terminal is attachable / detachable to / from the hardness meter main body, it is possible to select a measuring terminal suitable for the property of the surface to be measured and attach it to the hardness meter main body. Therefore, the measurement range is widened accordingly, and various measured surfaces can be measured.

Further, since the measuring terminal and the pressurizing member are elastically mounted on the hardness tester main body so that the elastic force can be changed, the measuring range can be expanded by adjusting the elastic force according to the property of the surface to be measured. effective.

[Brief description of drawings]

FIG. 1 is a plan view in which a part of a hardness meter for a soft material of the present invention is shown in section.

FIG. 2 is a cross-sectional view of a hardness meter portion that constitutes the hardness meter for soft material of the present invention.

FIG. 3 is a plan view of a display unit that constitutes the hardness meter for soft material of the present invention.

FIG. 4 is a side view of a display unit.

FIG. 5 is a side view showing an electric constant pressure loader in which the hardness tester of the present invention is incorporated.

FIG. 6 is a sectional view showing a conventional hardness tester.

[Explanation of symbols]

1 Hardness meter for soft material 2 Hardness meter section 3 Display section 4, a Fixed surface of d side 5, d Measuring terminal 6 Pressing member 7, b Hardness meter body 8 Signal transmitter 9 Load cell (pressure detector)

Claims (3)

[Claims] 1. A measurement terminal for pressing against a surface to be measured to detect a stress, a pressure member surrounding the measurement terminal, and the pressure member and the measurement terminal which are movably held in the axial direction and elastically mounted. A hardness tester body, and a signal transmitter that outputs a hold signal when the pressure member is pressed to the surface to be measured by a predetermined amount,
A pressure detector for measuring the stress received by the measurement terminal when the hold signal is transmitted when the measurement terminal is pressed to the surface to be measured together with the pressing member. Hardness tester for materials. 2. The hardness meter for a soft material according to claim 1, wherein the measuring terminal is attachable to and detachable from the hardness meter body. 3. The hardness meter for a soft material according to claim 1, wherein the elastic force of the measuring terminal and the pressing member elastically mounted on the hardness meter body can be changed.