JPH04130241A - Apparatus and method for measuring hardness of inner surface of rubber hose - Google Patents

Abstract

PURPOSE:To make it possible to measure the hardness of the inner surface of a rubber hose simply without cutting the hose by providing a plate spring to which a strain gage is stuck and the like on one side of the main body of a U-shaped measuring part, and providing a reaction-force receiving part on the other side. CONSTITUTION:A guide cover 8 at the front end of a U-shaped measuring part is slid and inserted through the mouthpiece part of a rubber hose. Then, an adjusting screw 6 is rotated, ad a reaction receiving piece 5 is pushed on the outer surface of the hose. Then, a main body 1 of a measuring part is pushed to the inner surface of the host at the opposite side by the reaction. At this time, a measuring piece 4 is pushed back in proportion to the hardness of the rubber at the inner surface of the hose. The measuring piece 4 pushes up the free end of a plate spring 2. In this way, the bending strain generated in the plate spring 2 is detected with a strain gage 3. The electric signal is inputted into a hardness display device 9 through a lead wire 3a. In the display device 9, the electric signal is converted into the hardness of the rubber, and the hardness is displayed. Thus, the hardness can be measured simply without cutting the hose.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for measuring the inner surface hardness of a rubber hose, and more particularly, to an improvement of an apparatus for measuring the inner surface hardness of a rubber hose for determining the durability of the rubber hose.

(Prior Art) Conventionally, in construction machinery and the like, there are many hydraulically driven devices including working machines, and a large number of rubber hoses are used in the circuits thereof. Since these hydraulic hoses are expensive, other hoses are often replaced in the event of a burst or depending on the appearance of the hose, except for those that have a specified replacement period as a safety part. but,
Since we may need to replace hoses that can still be used, we decided to measure the hardness of the rubber hose and quantitatively understand when it is time to replace it, since the hardness of the rubber hose is one of the characteristics of hose deterioration. When measuring the hardness of rubber, a hardness tester shown in FIG. 7 or 8 is generally used. When the pressurizing surface of these hardness testers is pressed against a rubber test piece, the indentation needle protruding from the pressurizing surface is pushed back by the rubber, and the pointer of the tester indicates the distance as hardness, so the indication scale is You can tell the hardness by reading it. Hardness testers are classified into spring type and constant force type depending on how the load is applied to the indenter, but in both types, the measurement surface of the target specimen must be smooth and the measurement surface must be smooth. The space on the surface side needs to be large enough not to interfere with measurements.

(Problem to be solved by the invention) However, when the above conventional hose bursts,
The reason for replacing it is because the high-temperature pressure oil leaks out due to a burst, which can cause burns if it hits a person, and can cause a fire in the vehicle if it hits a hot part such as an engine exhaust pipe. Additionally, when visually determining the degree of trauma to the hose, there is a problem in that it can be determined if the outside surface of the hose is damaged, but it cannot be determined if the inside surface of the hose has deteriorated. . Furthermore, when measuring the hardness of rubber, the outer surface of a rubber hose can be measured, but the value does not match the hardness of the inner surface, so it is necessary to measure the inner surface. A cap is attached to both ends, and the inner diameter of the cap is slightly smaller than the inner diameter of the hose. For this reason, when using a hardness tester based on conventional technology, a certain amount of space is required on the measurement surface side as described above, but since the inner diameter of the rubber hose is small, this space cannot be secured. Measurements cannot be made unless the rubber hose is cut to create a test piece. For this reason, the cut rubber hose cannot be used, the preparation of test pieces is time-consuming and troublesome, and measurement cannot be easily performed at a work site or the like. Another problem is that it is difficult to insert a measuring device because the cap is small.

The present invention focuses on the above-mentioned conventional problems and relates to an apparatus for measuring the inner surface hardness of a rubber hose. In particular, the present invention aims to improve the apparatus for measuring the inner surface hardness of a rubber hose in order to determine the durability of the rubber hose without cutting the rubber hose. There is.

(Means for Solving the Problems) In order to achieve the above object, in the first invention related to the present invention, a plate spring to which a strain gauge is attached and a needle-shaped measuring element are arranged at the tip of the plate spring. The measuring section is fixed to one side of the U-shaped measuring section main body, and a reaction force receiving section that can be adjusted with a screw is arranged on the other side of the U-shaped measuring section main body at a position corresponding to the measuring head. Further, in the second invention based on the first invention, the reaction force receiving part is pressed against the outer surface of the hose by rotating the adjustment screw, thereby applying a bending force to the leaf spring of the measuring part inserted into the hose, The bending strain that occurs in the leaf spring is detected by a strain gauge, and the amount of strain is converted into hardness and displayed on a hardness indicator outside the hose. Furthermore, in a third invention, in a device for measuring the inner surface hardness of a rubber hose in which the rear end of a leaf spring to which a strain gauge is attached is fixed to a U-shaped measuring section main body, the hose of the other U-shaped measuring section main body is The hardness of the opposing inner surface of the hose is measured by the reaction caused by the thrust of the screw in the reaction force receiver located on the outside.

(Function) According to the above configuration, since the hardness tester is rod-shaped, it can be easily inserted into the hose. Next, when the reaction force receiving part is pressed against the hose from the outside with a screw, the reaction force presses the measuring part body inside the hose against the inner surface of the hose, and the measuring element protruding from the measuring part body moves depending on the hardness of the rubber. Since it is pushed back and applies bending force to the leaf spring, the leaf spring is bent and bending distortion occurs. This bending strain is detected by a strain gauge attached to the leaf spring, and is input as an electrical signal to a hardness indicator on the outside of the hose. Therefore, if you actually measure the relationship between the amount of distortion in the leaf spring and the hardness of the rubber and establish a conversion formula,
The hardness indicator can convert the input electrical signal into hardness and display it. Therefore, if the degree of hardening of the inner rubber due to hose deterioration is used as a criterion for replacing the hose, the hardness of the inner surface of the hose is measured, and the necessity of replacing the hose is determined based on the obtained hardness measurement value, accidents caused by bursts can be prevented. Prevention and efficient machine management for preventive maintenance (Example) Examples of the rubber hose inner surface hardness measuring device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an outline of a hose inner surface hardness tester according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. 1. A measuring section 30 is disposed at one end, and a reaction force receiving section 40 is disposed at the other end. A part of the upper side of the U-shaped flat plate 1a on the side of the measurement unit 30 in the drawing has a cross section that is an arc, and the lower side 1b is a flat plane with a step as shown in FIG. 3, and a hole 1c is provided at the front end. The rear end of the leaf spring 2 is fixed to the rear end flat portion by a clamp ld and a machine screw 1e. A strain gauge 3 is attached to the lower surface of the leaf spring 2, and a measuring element 4 is welded to the front end, that is, the free end, of the leaf spring 2, as shown in FIG. The measuring tip 4 welded to the leaf spring 2 is inserted into the hole 1c of the measuring unit main body l, and the tip of the measuring tip 4 is a flat plate having the same shape as the measuring tip of a conventionally used rubber hardness tester. It protrudes from the top surface of 1a.

By the way, the relationship between the gauge head load, the distance between the pressurizing surface and the tip of the gauge head, and the hardness scale in the case of JIS A scale hardness of rubber is as shown in FIG. As a leaf spring that satisfies this relationship, the material is 5UPIG, the plate thickness is 1.0mm,
Width 3. Omm, length from fixed end to point of application 36.01
A strain gauge was attached at a position 5 mm from the fixed end using a cantilever spring of mm. JIS for this leaf spring
The relationship between the A scale hardness and the amount of strain at a position 5 mm from the fixed end is as shown in FIG.

A reaction force receiving part 40 is disposed at the end of the other flat plate 1h of the U-shaped measuring part main body 1 at a position facing the measuring element 4 of the measuring part 30 (located on the outer surface of the hose during measurement). The reaction force receiving part 40 is rotatably connected to the adjustment screw 6 by a pin 7 that engages a reaction force receiving piece 5 in a groove of the reaction force receiving piece 5 . When the reaction force receiving piece 5 is in contact with the hose 20 even when the adjusting screw 6 is turned, it is supported by the pin 7 that engages with the groove of the reaction force receiving piece 5 and does not rotate.

In the above configuration, the operation will be explained next. The measuring part front end guide cover 8 of the U-shaped end of the hose inner surface hardness tester is brought into contact with the mouthpiece 21 and the hose inner surface 22 from the mouthpiece of the rubber hose, and is inserted while sliding. Next, when the adjustment screw 6 is rotated and the reaction force receiving piece 5 is pressed against the outer surface of the hose, the measuring section main body 1 is pressed against the inner surface of the hose on the opposite side as a reaction. At this time, the probe 4 is pushed back in proportion to the hardness of the rubber on the inner surface of the hose, and the probe 4 pushes up the free end of the leaf spring 2. As a result, the leaf spring 2
The bending strain generated in the hardness indicator 9 is detected by the strain gauge 3, and an electric signal is input to the hardness indicator 9 via the lead wire 3a. The hardness indicator 9 converts this electrical signal into the hardness of the rubber and displays it.

When the measurement is completed and the adjustment screw 6 is rotated to return the reaction force receiving part 5 upward, the measuring part inserted into the hose becomes free, and the guide cover 8 is brought into contact with the inner surface 22 of the hose and the mouth part 21, and the sliding part is removed. You can pull it out while holding it.

The method for measuring the inner surface hardness of a rubber hose described in this embodiment can be used to measure the inner surface hardness of a fluid rubber hose used not only in construction machinery but also in various mechanical devices.

(Effects of the Invention) As explained above, according to the present invention, when the hardness measuring part is inserted into the hose and the reaction force receiving part is pressed against the hose from the outside of the hose with a screw, the reaction force causes the inside of the hose to Using a hose inner surface hardness tester, the measuring part body is pressed against the inner surface of the hose, and the measuring tip protruding from the measuring part body is pushed back depending on the hardness of the rubber to apply bending force to the leaf spring. The amount of bending strain that occurs is detected by a strain gauge attached to a leaf spring, and is also displayed on a hardness indicator outside the hose, so it is possible to check the inner hardness of hoses removed from each mechanical device or new hoses. , it can be easily measured without cutting the hose. By measuring the hardness using the method for measuring the inner surface hardness of a rubber hose according to the present invention, it is possible to objectively judge the degree of deterioration of the rubber on the inner surface of the hose, thereby preventing sudden accidents such as hose bursts. . In addition, the method for measuring the inner hardness of rubber hoses according to the present invention can be easily applied at work sites, etc., and since it is a non-destructive measurement method, hoses that have not deteriorated can be used again with the measuring device. An excellent effect can be obtained.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing an outline of the hose inner surface hardness measuring device of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a partial side view of the measuring part, and Fig. 4 is A perspective view of the tip of the leaf spring. Figure 5 is a diagram showing the relationship between the probe load, the distance between the pressurizing surface and the tip of the indenter, and the hardness scale. Figure 6 is a diagram of the leaf spring used in the example. Figures 7 and 8 are front views of the conventional hardness tester, and Figure 9 shows the tip of the hydraulic hose. Shown partial side 1 ・
・ 2 ・ ・ 3 ・ ・ 4 ・ ・ 5 ・ ・ 6 ・ ・ 7 ・ ・ 8 ・ ・ 9 ・ ・ 20 ・ 30 ・ 40 ・ ・Measuring unit body, ・Plate spring, ・Strain gauge, ・Measure head, ・Reverse Force receiving piece, ・Adjustment screw, ・Bin, ・Guide cover/indicator, ・・Rubber hose, ・・Measuring part, ・・Reaction force receiving part,

Claims (3)

[Claims] (1) A plate spring to which a strain gauge is attached and a measurement unit with a needle-shaped probe at the tip of the plate spring are fixed to one side of the U-shaped measurement unit body, and the other side of the U-shaped measurement unit body is fixed. A device for measuring the inner surface hardness of a rubber hose, characterized in that a reaction force receiving part that can be adjusted with a screw is arranged at a position corresponding to a measuring point. (2) By rotating the adjustment screw and pressing the reaction force receiver against the outer surface of the hose, a bending force is applied to the leaf spring of the measuring part inserted into the hose, and the bending strain generated in the leaf spring is detected with a strain gauge. The inner hardness measuring device for a rubber hose according to claim 1, wherein the amount of strain is converted into hardness and displayed on a hardness indicator outside the hose. (3) In a rubber hose inner hardness measuring device in which the rear end of a leaf spring to which a strain gauge is attached is fixed to a U-shaped measurement unit body, a rubber hose located outside the hose of the other U-shaped measurement unit body A method for measuring the inner surface hardness of a rubber hose, characterized in that the hardness of the opposing inner surface of the hose is measured by the reaction caused by the thrust of a screw in a force receiving part.