JPH0442036A - Apparatus and method for measuring hardness of inner surface of rubber hose - Google Patents

Abstract

PURPOSE:To make it possible to detect durability by measurement without cutting a hose by inserting a hardness measuring part into the hoes, pushing an air bag to the inner surface of the hose, and pushing the main body of the measuring part to the inner surface of the hose with the reaction force. CONSTITUTION:When force for grasping a lever 8 is eased, a check valve 38 is opened by the force of a spring 36 with a piston 32, and air is sucked. An air bag 41 shrinks to the lowest position. Under this state, the front end of the measuring part of a rod-shpaed tester is inserted into a hose. When a handle 6 and the lever 8 are grasped, a check valve 39 is opened with the piston 32. Air at the side of a bottom 37 swells the bag 41, and the bag 41 comes close contact with the inner surface of the hose. A main body 1 of the measuring part is pushed to the inner surface of the hose at the opposite side by the reaction force. At this time, a pushing needle 4 is pushed back in proportion to the hardness of the rubber at the inner surface of the hose, and the free end of a plates spring 2 is pushed up. Thus, the bending strain generated in the plate spring 2 is detected with a strain gage and converted into the hardness. The result is displayed on a display device 11.

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. However, even those that can still be used may need to be replaced, so it has been proposed to measure the hardness of the rubber hose to determine when it is time to replace it. When measuring the hardness of rubber, a hardness tester shown in FIG. 9 or 10 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 the oil is that it bursts and releases high-temperature pressure oil, which can cause burns if it hits a person, or cause a fire in the vehicle if it hits the engine's exhaust pipe. Also,
When visually determining the degree of trauma to a hose, there is a problem in that it can be determined when the outside surface of the hose is damaged, but it cannot be determined when the inside surface of the hose is 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.As shown in Figure 11, hydraulic hoses have caps on both ends, and the The inner diameter 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 according to the present invention, the rear end of the leaf spring to which the strain gauge is attached is fixed to the measuring section main body, and the measuring section main body is fixed. A rod-shaped hardness tester, which is fixed to the front end of the tester body, is inserted into the port, air is sent from outside the hose, the air bag is opened, and the reaction force pushes the measuring part body against the opposing inner surface of the hose. , a presser needle attached to the leaf spring and protruding from the measuring part body by passing through a hole provided in the measuring part body is pushed back according to the hardness of the rubber and applies a bending force to the leaf spring, thereby causing the plate spring to bend. The bending strain generated in the 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. Further, in a second invention based on the first invention, a gauge is attached to measure the air sent from outside the hose. Furthermore, the third
In the invention, in an apparatus for measuring the inner surface hardness of a rubber hose, the strain gauge is attached, the rear end of a leaf spring is fixed to a measuring part body, and this measuring part body is fixed to the front end of a testing machine body. An air bag is attached to the hose, and when the measurement unit is inserted into or removed from the hose, air is removed from the air bag, and during measurement, air is sent from outside the hose to open the air bag, and the reaction force is used to spread the measurement onto the opposing inner surface of the hose. Measure by pressing the main body.

(Function) According to the above configuration, since the hardness tester is rod-shaped, it can be easily inserted into the port. Next, when air is sent to the air bag and pressed against the inner surface of the hose, the measuring unit main body can be pressed against the opposite inner surface of the hose by the reaction force. Additionally, air pressure can be read with a gauge and can be used as a guide when measuring hardness. Furthermore, since a measurement pressure area is provided on the gauge for when measuring, quantitative pressure can be ensured. The indenter protruding from the measurement unit body is pushed back depending on the hardness of the rubber and applies bending force to the leaf spring, causing the leaf spring to bend and bending strain. 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, by actually measuring the relationship between the amount of strain in the leaf spring and the hardness of the rubber and establishing a conversion formula, the hardness display 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. This allows for efficient machine management in terms of preventive maintenance.

(Example) Hereinafter, an example of the apparatus for measuring the inner surface hardness of a rubber hose according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram in a perspective view showing an outline of a hose inner surface hardness tester according to an embodiment of the present invention, and FIG. 2 is a side view of a hose inner surface hardness tester according to an embodiment of the present invention. 3 is a sectional view taken along line AA in FIG. 2. The measuring section main body 1 has a cross section in which the bottom surface is an arc, and the upper side is a flat surface with steps as shown in FIG. It is fixed by a clamp 1b and a machine screw 1c. A strain gauge 3 is attached to the upper surface of the leaf spring 2, and a fifth strain gauge 3 is attached to the front end, that is, the free end of the leaf spring 2.
As shown in the figure, a long hole 2a through which the indenter 4 is inserted is provided. The long hole 2a of the plate spring 2 and the hole 1a of the measurement unit main body l
The indenter 4 is inserted into the head 4a as shown in FIG.
It consists of a shaft part 4b having two parallel surfaces and sliding in a long hole 2a provided in the leaf spring 2, and a needle part 4C, and the tip of the needle part 4c is the same as that used conventionally. It has the same shape as the indenter of a rubber hardness tester, and protrudes from the bottom surface of the measurement unit main body l. Further, a retaining pin 4d that is in line contact with the lower surface of the leaf spring 2 is inserted into the shaft portion 4b of the pusher needle 4 in a direction perpendicular to the axis of the pusher needle 4.

Incidentally, the relationship between the indenter load, the distance between the pressurizing surface and the tip of the indenter, 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 SUP 10, the plate thickness is 1. Omm, radial 2
．． A cantilever spring with a length of 23.1 mm from the fixed end to the point of action was used, and a strain gauge was attached at a position 5 mm from the fixed end. The relationship between the JIS A scale hardness of this leaf spring and the amount of strain at a position 5 mm from the fixed end is as shown in FIG.

The rear end of the measuring unit main body 1 is fixed to the front end of a tubular shaft 5a of the tester main body 5, and an air pump device 30 is fixed to the rear end of this shaft 5a. A handle 6 is fixedly attached to the handle. In addition, a bracket 9 is attached to the pump case 31 of the air pump device 130.
is fixedly attached to the bracket 9, and a lever 8 which is rotatable via a pin 7 is connected to the bracket 9. A piston 32 of an air pump device 30 is connected to the lever 8 via a rod 33 at a pin 34 in a hinged manner. An O-ring 35 is fitted on the outer diameter of the piston 32, and a spring 36 is provided on the bottom (M) side to abut against the piston 32 and return the piston 32.

A check valve 38 and a check valve 39 are provided on the bottom 37, and an air tube 40 is connected from the check valve.
is connected to the air bag 41 that receives the reaction force, and checks the air flowing from the air pump device 30 to the air bag 41. Further, the bottom 37 is connected to an air gauge 42 through a passage 42. Further, an air bag 41 is provided in contact with the measurement unit main body 1, and the air bag 41
Air is supplied and discharged from the air pump device 30 through an air tube 40 disposed in the tubular shaft 5a of the testing machine main body 5. The lead wire 3a of the strain gauge 3 attached to the leaf spring 2 is connected to the inside of the shaft 5a of the testing machine body 5 and the handle 6.
The hardness indicator 11 passes through the inside and exits from the lower end of the handle 6.
The operation of the above configuration connected to the above will be explained next. Before inserting the front end of the measuring section of the hose inner hardness tester into the mouthpiece of the rubber hose, if you loosen the force on the lever 8, the piston 32 will open the check valve 38 by the force of the spring 36 and drain the air inside the air bag 41. air tube 40
Since the air bag 41 is sucked through, the air bag 41 deflates to the lowest position (the state shown in FIG. 2). In this state, the front end of the measurement part of the hose inner surface hardness tester is passed through the mouthpiece of the rubber hose, and the tester is inserted so that the indenter 4 is at the measuring position of the inner surface rubber of the hose. Next, when the handle 6 and lever 8 are squeezed and the lever 8 is moved toward the handle 6, the check valve 39 is opened by the connected piston 32, and the air from the bottom 37 side passes through the air tube 40 to receive the reaction force. The air bag 41 is inflated and brought into close contact with the inner surface of the hose. The air bag 41 is further inflated by the pressure in the measurement pressure range within the air gauge 42 and is pressed against the inner surface of the hose, and as a reaction, the measuring section main body 1 is pressed against the inner surface of the hose on the opposite side. At this time, the pusher needle 4 is pushed back in proportion to the hardness of the rubber on the inner surface of the hose, and the pusher needle 4 pushes up the free end of the leaf spring 2 via the retainer pin 4d. As a result, the bending strain generated in the leaf spring 2 is detected by the strain gauge 3, and an electric signal is input to the hardness indicator 11 via the lead wire 3a. The hardness indicator 11 converts this electrical signal into hardness and displays it. When the measurement is completed and the force of gripping the lever 8 is weakened, the piston 32 opens the check valve 38 by the force of the spring 36 and suctions the air inside the air bag 41 through the air tube 40, so the air bag 41 deflates and reaches its maximum position. Returning to the lower position (as shown in Figure 2), the hardness tester can be pulled out from the hose.

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, the hardness measuring section is inserted into the hose, the air bag is pressed against the inner surface of the hose, and the measuring section main body is pressed against the inner surface of the hose by the reaction force. The amount of bending strain generated in the leaf spring is measured using a hose inner hardness tester in which a pusher needle protruding from the measurement unit body is pushed back according to the hardness of the rubber and applies bending force to the leaf spring. This is detected by a strain gauge attached to the spring, and is also displayed on a hardness indicator outside the hose, so you can check the inner hardness of hoses removed from each mechanical device or new hoses without having to cut them. Can be easily measured. 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 measured diameter. You can get the excellent effect of

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the hose inner surface hardness measuring device of the present invention, showing a state in which the lever is pushed in and the cover is opened. Figure 2 is a partial side view of the hose internal hardness tester, Figure 3 is a sectional view taken along line A-A in Figure 2, Figure 4 is a partial side view of the measuring section, and Figure 5 is the tip of the leaf spring. 6 is a perspective view of the indenter, FIG. 7 is a diagram showing the relationship between the indenter load, the distance between the pressure surface and the tip of the indenter, and the hardness scale, and FIG. 8 is an example. JISA scale hardness of the leaf spring used and 5 from the fixed end
Figures 9 and 10 are a front view of a conventional hardness tester. Figure 11 is a partial side view of the tip of a hydraulic hose. ...Measurement unit body, ...Plate spring, ...Strain gauge, ...Indenter, ...Testing machine main body, 30, 32, 38. 40 ・ 41 ・ 42 ... Air pump device, ... Piston, 39 ... Check valve, ... Air tube, - Air bag, ... Air gauge,

Claims (1)

[Scope of Claims] (1) A rod-shaped hardness tester consisting of the rear end of a leaf spring to which a strain gauge is attached is fixed to a measuring part body, and the measuring part main body is fixed to the front end of a testing machine main body. Insert it into the hose, send air from outside the hose, open the air bag, use the reaction force to press the measurement unit body against the opposing inner surface of the hose, and insert it through the hole provided in the measurement unit body, which is attached to the leaf spring. The push needle that protrudes from the measurement unit body is pushed back depending on the hardness of the rubber and applies bending force to the leaf spring, and the strain gauge detects the bending strain that occurs in the leaf spring and measures the hardness outside the hose. A device for measuring the inner surface hardness of a rubber hose, characterized in that the amount of strain is converted into hardness and displayed on a display (2) A gauge is attached to the hose for measuring air sent from outside the hose (1)
) Rubber hose inner hardness measuring device. (3) In a rubber hose inner hardness measuring device in which the rear end of a flat spring to which a strain gauge is attached is fixed to the measuring unit body, and this measuring unit body is fixed to the front end of the testing machine body, air is supplied to the measuring unit body. When the bag is attached and the measurement unit body is inserted into or removed from the hose, air is removed from the air bag, and during measurement, air is sent from outside the hose to open the air bag.
A method for measuring the inner surface hardness of a rubber hose, which is characterized in that the reaction force is used to press the measurement unit main body against the opposing inner surface of the hose.