JPH0688777A - Product drop impact test device - Google Patents

Abstract

PURPOSE:To reduce the friction resistance in sliding time of a piston in a product drop impact testing device for testing the strength against impact damage of the product by pushing down the piston with a drop energy of a drop table and then giving a shock waveform which is generated by the gas resistance inside the cylinder. CONSTITUTION:Airtight retention materials 21a and 21b are provided on a surface contacting a piston 8 of a protruding part 20 at the upper part of a cylinder 6 for preventing the jump-out of the piston 8 and on the upper surface of the piston 8 contacting the protruding part 20, thus eliminating the airtight retention materials 21a and 21b contacting the inner surface of the cylinder 6, thus suppressing impact acceleration, shortening starting time, suppressing distortion of a steady acceleration part, and reducing vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a product drop impact test device used for measuring mechanical shock vulnerable strength of various products, parts and the like (hereinafter referred to as "test sample"). .

[0002]

2. Description of the Related Art FIGS. 3 and 4 are views showing the structure of a conventional product drop impact test apparatus, in which 1 is a base and 2 is a base.
Is a pair of guide rods provided on both sides of the upper part of the base 1,
3 is a drop table which is fitted to the guide rod 2 and is vertically movable, 4 is an impact head which is vertically attached below the drop table 3, 5 is a sample to be tested, and 6 is a base. The cylinder 7 mounted on 1 is a through hole formed in the upper part of the cylinder 6, and the impact head 4 penetrates this hole when dropped.

Reference numeral 8 is a piston provided in the cylinder 6 and slidable in the vertical direction. Reference numeral 9 is a plurality of O-rings fitted to the outer periphery of the piston 8 to maintain airtightness in the cylinder 6.
Is a high-pressure gas container filled with an inert gas (for example, nitrogen gas), 11 is a gas supply pipe connecting the high-pressure gas container 10 and the cylinder 6, and 12 is a gas pressure adjustment provided in the gas supply pipe 11. Reference numeral 13 is a gas adjusting valve for adjusting the gas pressure, 14 is a pressure gauge for displaying the gas pressure, and 15 is a control device for controlling the elevating operation of the drop table 3.

Next, the operation of the conventional device will be described.
The sample 5 is placed on the drop table 3 and fixed by a jig (not shown). Next, the control device 15 is operated to raise the drop table 3 along the guide rod 2 to the test drop height by using an elevating device (not shown), and locked at that position by a holding mechanism (not shown). Keep it.

Next, the gas pressure in the cylinder 6 is adjusted by the gas pressure adjuster 12 while checking it with the pressure gauge 14 to change the gas resistance, and the maximum value of the impact acceleration when the piston 8 slides is adjusted. As shown in FIG. 4, the piston 8 is raised and brought into pressure contact with the upper protruding portion of the cylinder 6.

When all of the above preparations are completed, the control device 15 is operated to operate the holding mechanism to release the lock, and the fall table 3 is allowed to freely fall along the guide rod 2 to form the through hole 7. It is penetrated and the impact head 4 collides with the piston 8.

At the time of this collision, the piston 8 is pushed downward by the kinetic energy of the drop table 3 and slides downward in the cylinder 6, and the inert gas in the cylinder 6 is stored and compressed to increase the gas pressure. .

When the kinetic energy of the falling table 3 becomes zero due to the gas pressure offset and the sliding displacement of the piston 8 reaches the maximum position, the pressure of the inactive gas stored and compressed through the piston 8 this time. The energy causes the drop table 3 to bounce upward along the guide rod 2.

While the fall table 3 is floating, the holding mechanism locks the drop table 3 to prevent the impact head 4 from dropping again and colliding with the piston 8, and the work is completed.

Next, the impact acceleration will be described with reference to FIGS. 5 is a diagram showing the relationship between the load applied to the impact head 4 and the displacement of the impact head 4 when the impact head 4 collides with the piston 8, and FIG. 6 is a diagram showing the relationship between impact acceleration and time. In the figure, the portion from the starting point to (A) shows the change due to the elastic characteristics of the tip of the impact head 4,
The part shown in (B) is a so-called steady acceleration part, and shows a change due to the elastic characteristics of the inert gas filled in the cylinder 6.

As shown in FIGS. 5 and 6 from the starting point to (A), the value of the impact acceleration generated on the drop table 3 when the impact head 4 collides with the piston 8 is the kinetic energy of the drop table 3. And the pressure energy of the inert gas that pushes the piston 8 upward rises rapidly until they are balanced.

Then, as shown in FIGS. 5 and 6B,
When the piston 8 returns to its original position due to the rise in the gas pressure that has been stored and compressed, the shock acceleration gradually increases in a mountain shape and then decreases when it reaches the maximum value, after which the part (B) is reached. After passing, it drops sharply. When the impact head 4 is separated from the piston 8, the impact acceleration value becomes zero.

As prior art documents for this type of apparatus, Japanese Patent Publication Nos. 54-4029 and 55-5456 are available.
Japanese Patent Publication No. 59-33852 and Japanese Patent Application No. 1-
No. 174551 exists.

[0014]

The problem to be solved by the present invention is that in the conventional device, in order to maintain the airtightness in the cylinder 6, airtightness such as a plurality of O-rings is provided on the outer circumference of the piston 8 in contact with the inner surface of the cylinder 6. Since the holding material is fitted, the frictional resistance when the piston 8 slides in the cylinder 6 is large, so that the rise time of the shock waveform is long, a large acceleration is generated at the time of rising, and the steady acceleration There is a point that the portion is distorted from the ideal waveform that is originally ideal due to distortion or the like.

[0015]

SUMMARY OF THE INVENTION According to the present invention, an airtight holding material is provided on a surface of a protruding portion of a cylinder upper portion which prevents the piston from popping out and which is in contact with the piston, and an upper surface of the piston which is in contact with the protruding portion. What is done is the most important feature.
Therefore, it is possible to eliminate the frictional resistance due to the airtight holding material when the piston slides in the cylinder, suppress the acceleration at the time of rising of the waveform, suppress the distortion of the steady acceleration part, and shorten the rising time. .

[0016]

FIG. 1 is a diagram for explaining the outline of the present invention.
In the figure, the same reference numerals as those in FIG. 4 denote the same or corresponding parts,
20 is a cylinder 6 to prevent the piston 8 from popping out.
A protruding portion provided on the upper portion, 21a is an airtight holding material provided on a surface of the protruding portion 20 that abuts the piston 8, and 21b is an airtight holding material provided on an upper surface of the piston 8 that abuts the protruding portion 20. Then, for example, an O-ring or the like is used for these airtightness holding materials.

FIG. 2 is a diagram showing an embodiment of the present invention. In this embodiment, the cylinder is a double-structured cylinder unit. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, 16 is an impact rod, 17 is a highly rigid pad,
Reference numeral 22 denotes a projecting portion provided at the lower portion of the cylinder 6 to prevent the piston 8 from falling, 23 denotes a flange portion of the cylinder 6, and 60 denotes the entire double-structured cylinder unit.

In addition, in the configuration of the entire apparatus, the cylinder unit 60 is placed on the base 1 instead of the cylinder 6, and the impact head 4 mounted below the drop table 3 includes the impact rod 16 and the impact rod 16. It is the same as the conventional device shown in FIG. 3 except that it is composed of a high-rigidity pad 17 attached to the lower end.

The cylinder unit 60 has a flange portion 23.
It has a double structure having a cylinder 6 screwed therein and is provided with a piston 8 which is vertically slidable in the cylinder 6.

An airtight holding member 21a is provided on the surface of the protruding portion 20 that abuts the piston 8, while the protruding portion 20 is
The airtightness holding material 21b is disposed on the upper surface of the piston 8 that comes into contact with the
The airtightness in the cylinder 6 and the vibration at the time of collision are blocked.

Since the airtight holding member 9 which contacts the inner surface of the cylinder 6 on which the piston 8 slides as in the conventional device is omitted, only the inert gas is filled between the cylinder 6 and the piston 8. It is possible to control the acceleration at the rise of the shock waveform and shorten the rise time. Other parts are the same as the conventional example.

Next, the operation will be described. The sample 5 is placed on the drop table 3 and fixed by a jig (not shown). Next, the control device 15 is operated to raise the drop table 3 along the guide rod 2 to the test drop height by using an elevating device (not shown), and locked at that position by a holding mechanism (not shown). Keep it.

Next, the gas pressure in the cylinder unit 60 is checked by the gas pressure adjuster 12 while checking it with the pressure gauge 14 to change the gas resistance, and the maximum value of the impact acceleration when the piston 8 slides is adjusted. Then, the piston 8 is raised to bring the upper surface of the piston 8 into contact with the protruding portion 20 at the upper portion of the cylinder 6, and the airtight holding members 21a and 21b are pressed to maintain the airtightness in the cylinder 6.

When all the above preparations are completed, the controller 15 is operated to operate the holding mechanism to release the lock, and the fall table 3 is allowed to fall freely along the guide rod 2 to form the through hole 7. It is penetrated and the impact head 4 collides with the piston 8.

At the time of this collision, the piston 8 is pushed downward by the kinetic energy of the drop table 3 and slides downward in the cylinder 6, and the inert gas in the cylinder unit 60 is stored and compressed to increase the gas pressure. Let

As described above, the airtight holding member 9 in contact with the inner surface of the cylinder 6 on which the piston 8 slides is omitted, and the resistance against sliding of the piston 8 is only the pressure of the inert gas, and the drop table After the kinetic energy of 3 and the energy (pressure) of the inert gas are balanced, the piston 8 slides smoothly.

Further, by the airtightness holding materials 21a and 21b,
The vibration between the piston 8 and the protrusion 20 on the upper portion of the cylinder 6 is blocked, and the vibration received by the cylinder 6 can be largely blocked.

When the kinetic energy of the falling table 3 becomes zero and the sliding displacement of the piston 8 reaches the maximum position by being offset by the gas pressure, this time the pressure of the inert gas stored and compressed via the piston 8 is compressed. The energy causes the drop table 3 to bounce upward along the guide rod 2.

While the drop table 3 is floating, the drop table 3 is locked by the holding mechanism to prevent the impact head 4 from dropping again and colliding with the piston 8 to complete the work.

As described above, according to the present invention, the piston 8
By disposing the airtight holding members 21a and 21b on the surface of the protruding portion 20 of the upper portion of the cylinder 6 that contacts the piston 8 and the upper surface of the piston 8 that contacts the protruding portion 20, Makes it possible to reduce the frictional resistance when sliding in the cylinder 6, greatly suppress the acceleration at the time of rising of the waveform, shorten the rising time, and suppress the distortion of the steady acceleration portion.

In the above embodiment, the airtight holding member 21 is provided on both the protruding portion 20 and the upper surface of the piston 8, but either one may be provided, and the protruding portion 20 and the upper surface of the piston 8 may be provided. The vibration of the cylinder unit 60 can be further blocked by adopting a structure in which a vibration blocking member (not shown) is placed on either one or both of them, and then the airtight holding member 21 is placed.

[0032]

As described above, in the product drop impact test apparatus of the present invention, the airtight holding member is arranged on the upper portion of the piston and the protruding portion of the upper portion of the cylinder that abuts on the piston, and the airtight holding member is in contact with the inner surface of the cylinder. By omitting the material, there are advantages that the frictional resistance during sliding of the piston can be alleviated, the acceleration at the time of rising of the waveform can be greatly suppressed, the rising time can be shortened, and the distortion of the steady acceleration portion can be suppressed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the outline of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional device.

FIG. 4 is a diagram showing a configuration inside a cylinder of a conventional device.

FIG. 5 is a diagram showing a relationship between a load and a displacement received by the impact head.

FIG. 6 is a diagram showing a relationship between time and impact acceleration.

[Explanation of symbols]

 4 Impact Head 6 Cylinder 8 Piston 20 Projection 21a, 21b Airtight Holding Material 23 Flange 60 Cylinder Unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Iijima 2-14-40 Ofuna, Kamakura City Mitsubishi Electric Corporation Life Systems Research Institute (72) Inventor Kozo Nakano 2-14-40 Ofuna, Kamakura City Mitsubishi Electric Corporation Company Life Systems Research Center

Claims (1)

[Claims] 1. A piston provided in a cylinder filled with gas set to a desired pressure is pushed down by the drop energy of a drop table to give a shock waveform generated by the gas resistance in the cylinder, so that the product is easily damaged by shock. In a product drop impact tester for testing the strength of a product, the protrusion of the upper part of the cylinder that prevents the piston from jumping out is pressed against the face of the piston that contacts the piston and the upper face of the piston that contacts the protrusion. A product drop impact test device characterized by arranging an airtight holding material for shielding between the cylinder and the piston according to the above.