JPH06117984A - Method and apparatus for measuring hardnesses of rubber and plastic - Google Patents

Abstract

PURPOSE:To realize improvements for an accuracy and reproducibility of a measured value only by recording a pressing speed at the time of measuring by applying a pressing load to an element to be measured at a constant or a variable speed and measuring a numeric value of the loading speed. CONSTITUTION:A screw 10 is engaged with a loading rod 9 passed perpendicularly through ends of upper and lower arms 8 extended horizontally in a lateral direction from a strut 7, and a lifting arm 5 is mounted. A hardness meter 2 is mounted at a lower end of the rod 9, and a pressing weight 6 is mounted at an upper end. An element to be tested is placed on a measuring base 1. A drive motor 3 is rotated at a constant speed, and a pulley 4 is further rotated by a belt to rotate the screw 10. As a result, since the arm 5 meshed with the screw 10 is, for example, moved down to fall a fame, the meter 2 is brought into contact with the element to be measured at the constant speed and further pressed. Thus, hardness test can be conducted for the same material under the same conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the hardness of elastic bodies, and more particularly to a method for measuring the hardness of rubber and plastics and a measuring apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, there have been two methods for measuring the hardness of elastic materials such as rubber and plastic: a vulcanized rubber physical test method (JIS K 6301) and a plastic durometer hardness test method (JIS K 7215). The method was used a lot.

The test of "JIS K 6301" is for measuring items such as tensile strength, permanent elongation, hardness, aging, peeling, tearing, permanent strain, twisting and bending of a vulcanized rubber. As a general rule, there are three types of tests: "spring type hardness test (A type and B type)", "constant load (Olzen) type hardness test" and "constant load (Busey-Johns) type hardness test". .

On the other hand, the test of "JIS K 7215" is a durometer A hardness and a D hardness of plastic (using an indenter, a test load that changes corresponding to the depth of the depression is applied to the sample The value obtained from the depth H) is measured, and the range of the durometer hardness is A
The hardness and D hardness are both about 20-90. For this test rod, a durometer (testing machine) equipped with a machine frame, indenter, loading device, and hardness indicating device must be used, and the load, holding, and unloading of the load must be performed appropriately. It is said that. In particular, the durometer holder is
As shown in FIG. 4, it is used to obtain good reproducibility, so stable operation is possible, the indenter shaft is vertical when the durometer is attached, and the upper surface of the sample stand is horizontal. The proper conditions are that it is perpendicular to the indenter axis of the durometer, the mass of the weight is about 1 kg for the type A durometer and about 5 kg for the type D durometer.

In any of such test methods, when the pressure surface of the hardness tester is pressed against the surface of the object to be measured with a specified load, the pressing needle protruding from the center hole of the pressure surface by elastic force is measured. This is a kind of indentation hardness measurement method in which the hardness of a material pushed back is quantitatively measured. In addition, these test methods can be performed in a relatively short time, and since it is possible to measure by simply holding the hardness tester by hand or attaching it to a load device, it is widely adopted because it does not require a large-scale test device. There is. However, various new materials have been developed in recent years, and the need for a hardness tester having higher accuracy and reproducibility than conventional ones has been increasing, and various improved machines have been developed.

For example, a rubber hardness tester of Japanese Utility Model Laid-Open No. 60-163347 has been developed and publicized. This hardness meter has little variation in the rubber hardness measurement value of the rubber test piece,
In addition, the present invention relates to an air-type rubber hardness tester that can quickly measure rubber hardness, and a spring-type hardness tester placed above the bed for mounting test pieces is fixed to the lower end of the piston rod that expands and contracts in the vertical direction of the air cylinder. In order to measure the rubber hardness of the air cylinder, the optimum load value (optimal pressure value) and optimum speed value that have been obtained in advance are measured on the air cylinder. A gap is left between the dead point and the bed for placing the test piece so that a non-contact state can always be maintained. And
The specific configuration thereof will be described below as shown in FIG. First, switch valve 26 from OFF to O
When moving to N, air reaches the speed controller 25a through the switching valve 26, enters the air cylinder 22, and
Next, the air cylinder 22 operates and the piston rod 23
Of the spring type hardness meter 21 connected to the piston rod 23 at the same time descends and the needle 30
Comes into contact with the rubber test piece 28 set on the bed 29, and the pressing force thereof causes the needle 30 of the hardness meter 21 to rotate clockwise,
Measure the rubber hardness on the display scale at the time of stopping. At this time, the residual air below the piston of the cylinder 22 is
It is discharged from the outlet of the switching valve 26 through the speed controller 25b. When the switching valve 26 is switched from ON to OFF after measurement, the piston rod is activated by the operation of the air cylinder 22.
Along with 23, hardness meter 21 is also returned to its original position.

When the switching valve 26 is operated and the hardness meter 21 is returned to the elevated position, the piston of the cylinder 22 is pushed up through the speed controller 25a and at the same time the residual air above the cylinder 22 passes through the speed controller 25a. Is discharged from the discharge port of the switching valve 26.

The hardness meter 21 has a needle 30 and a needle 30 at the tip thereof connected by a spring, and the hardness meter 21 is attached to a rubber test piece 28.
When it is pressed against, the needle portion is pushed into the hardness meter 21 side, and the needle 30 rotates by the pushed amount. In this way, when the measurement of the rubber test piece 28 is completed, the position of the rubber test piece 28 on the bed is appropriately shifted, and the above operation is repeated to repeat the rubber test piece 28.
It is possible to sequentially measure the hardness at a plurality of points.

[0009]

Recently, the demand for elastic materials such as rubber and plastics has increased, and as the range of use has expanded, quality requirements have increased, and their fineness has been required. Therefore, it is necessary to further improve the conventional test method and to improve the tester itself to meet these requirements, and the quality of this kind of product, that is, the hardness must be accurately measured. In particular, the measured values of hardness of rubber and plastics vary depending on the pressing speed of the pressing surface, that is, the pressing speed of the pressing needle. Therefore, the conventional JIS standard test method cannot meet these requirements.

[0010]

The present invention was developed to obtain a measured value that cannot be obtained by the conventional method, and a constant pressing load is applied to an object to be measured of rubber and plastic hardness. At the same time, a pressing load is applied to the object to be measured at a constant speed or a variable speed, and the hardness of the elastic body whose indication value is likely to fluctuate is further accurately measured by numerical measurement of the load speed, and a rubber, In order to provide a method for measuring plastic hardness, and also to provide a measuring stand composed of two upper and lower arms that are horizontally fixed to a column that stands upright on a base, and a support that allows the upper and lower arms of the measuring stand to move up and down. A load rod that penetrates the rod and mounts a weight that applies a constant pressing load to the measured object at the upper end thereof, and a hardness meter for measuring the hardness of the measured object at the lower end, Vertical movement of the load bar The present invention provides a rubber and plastic hardness measuring device characterized by comprising a pulley and a drive motor that rotates via a belt. Further, a threaded portion is formed on the load bar, and a lift arm is fitted on the threaded portion. It is to provide a measuring device in which the load bar can be lifted and lowered freely.

[0011]

[Action]

(1) A constant pressing load is applied to the object to be measured of rubber and plastic hardness, and a pressing load is applied to the object to be measured at a constant speed or a variable speed, and the indicated value fluctuates by numerical measurement of the load speed. This is a method for accurately measuring the hardness of an elastic body, so the accuracy and reproducibility of measured values can be improved by recording the pressing speed during measurement without changing the conventional basic measurement method. It can be realized. Specifically, for the measurement of hardness, a device that can set or measure the pressing speed arbitrarily is used, and the pressing speed at the time of measurement is recorded as one element of the measurement data,
When measuring objects of the same type, unify the pressing speed as much as possible, and when comparing measured values (hardness) with different pressing speeds, consider the pressing speed and make a relative comparison. If the values are relatively large and opposite, it is determined that the measured value is relatively small).

(2) A measuring base formed by horizontally fixing two upper and lower arms to a supporting column standing on a base, and a supporting rod capable of moving up and down are passed through the upper and lower arms of the measuring base. And, a weight bar for applying a constant pressing load to the object to be measured is placed on the upper end thereof, and a hardness bar for measuring the hardness of the object to be measured is attached to the lower end, and a load bar above and below the load bar. It consists of a drive motor that rotates through a pulley and a belt.
Furthermore, a measuring device that realizes the above-described measuring method is provided by forming a threaded portion on the load bar, and by using a rubber and plastic hardness measuring device in which a lift arm is pushed into the threaded portion and the load rod can be raised and lowered freely. Can be provided. Specifically, the strength of the stress generated corresponding to the pressing force applied by the pressing needle of the hardness meter can be converted into the distance by which the pressing needle is pushed back and measured. In addition, the main cause of the instability of the measured value of the hardness tester is that the pressing force applied by the pressing needle is not uniform. Naturally, the difference will appear. The ununiformity of the pressing force is due to the difference in the pressing speed of the hardness meter, which appears as the difference in kinetic energy, which affects the pressing force applied to the tip of the pressing needle. . Also, in the actual measurement, when a hardness meter is attached to the load device for measurement, a reference weight or other method is used to apply a pressing force (1 Kg or 5 K
g) is determined and the pressing speed is determined by an oil damper, air damper or other method, but since the pressing speed is displayed and recorded numerically, the measurement speed is not uniform if the measurement date and time or measuring device is different. This makes it possible to make a considerable difference in the actual pressing force. Furthermore, when the hardness meter is held by a measurer by hand, the reference weights are not used and the measurer's manual adjustment does not affect the pressing force and the pressing speed. Become. For the above reasons, the measurement speed is an important factor for improving the measurement accuracy and the reproducibility of measured values.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a rubber and plastic hardness measuring apparatus according to the present invention. The basic structure of the apparatus is a conventional plastic durometer testing machine. This tester comprises a measuring table 1, a column 7 standing upright on it, and two upper bowls 8 extending horizontally from the column 7 in the lateral direction.
And lower bowl 8, a load rod 9 vertically penetrating the upper and lower arms 8 and a drive motor 3 mounted on the lower arm 8.
Etc. are the main components. Further, a screw 10 is inserted into the load bar 9 and a lift arm 5 is mounted thereon, and a manual lever (not shown) can be attached to the arm 5 to move the load bar 9 up and down. is there. Further, the hardness meter 2 is attached to the lower end of the load rod 9, and the weight 6 for pressing is attached to the upper end. When the test is performed, the power switch, the pressing speed control switch, the elevating switch, the fine feed switch, and the like of the measuring table 1 are operated.

Next, the operation method will be described. First, the object to be tested is placed on the measuring table 1, the drive motor 3 is rotated at a constant speed, and the pulley 4 is rotated by a belt to rotate the screw 10.
To rotate. As a result, the lift arm 5 meshing with the screw 10 moves downward, for example, to lower the frame 11, so that the hardness meter 2 contacts the object to be measured at a constant speed and is further pressed. The hardness test can be performed under the same conditions.

The measured values obtained by this measuring device are
The measurement table is shown in Table 1.

[0016]

[Table 1]

[0017]

According to the measuring method of the present invention, the accuracy and reproducibility of the measured value can be improved by simply recording the pressing speed at the time of measurement without largely changing the conventional measuring method. Can be made.

According to the measuring device of the present invention, the following effects can be obtained.

(A) Since the load speed of the tester can be measured numerically or numerically by controlling the rotational speed of the motor, it is possible to accurately measure a soft material whose indication value of the hardness meter is apt to vary depending on the pressing speed. B. By combining a tester and a digital hardness tester, automatic measurement can be performed and labor can be saved. C. By moving the load bar and hardness meter up and down electrically, the physical load on the measurer can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a front view showing a measuring device according to the present invention.

FIG. 2 is a side view of the measuring device shown in FIG.

FIG. 3 is an explanatory schematic diagram of a conventionally known rubber hardness meter.

FIG. 4 is an explanatory schematic view of a conventionally known durometer holding table.

[Explanation of symbols]

1 Measuring table 2 Hardness meter 3 Drive motor 4 Pully 5 Lift arm 6 Weight 7 Strut 8 Upper and lower arm 9 Load bar 10 Screw 21 Spring type hardness meter 22 Cylinder 23 Piston rod 24 Air hose 24a, 24b Branch circuit 25a, 25b Speed controller 26 Switching valve 28 Rubber test piece 29 Bed 30 Needle 31 Weight 32 Arm 33 Durometer 34 Pointer 35 Indenter 36 Strut 37 Sample 38 Sample stage 39 Lever

Claims (3)

[Claims] 1. A constant pressing load is applied to an object to be measured of rubber and plastic hardness, and a pressing load is applied to the object to be measured at a constant speed or a variable speed, and the load speed is numerically set and measured. A method for measuring the hardness of rubber and plastics, characterized by accurately measuring the hardness of an elastic body whose indicated value easily changes. 2. A measuring table, which is formed by horizontally fixing two upper and lower arms to a column that stands upright on a base, and a vertically movable support rod that penetrates through the upper and lower arms of the measuring table. A weight bar that applies a constant pressing load to the object to be measured is placed on the upper end thereof, and a hardness bar for measuring the hardness of the object to be measured is attached to the lower end, and the load bar moves up and down. A rubber and plastic hardness measuring device comprising a pulley and a drive motor that rotates via a belt. 3. The rubber and plastic hardness measuring device according to claim 2, wherein a threaded portion is formed on the load rod, and a lift arm is fitted and pushed on the threaded portion to freely move the load rod up and down.