JPH08247752A - Displacement detection device - Google Patents

Abstract

PURPOSE: To prevent buckling from being generated easily at the center of bellows, to prevent the bellows from being damaged, and hence to improve durability by feeding a spindle through the center opening of a guide ring and at the same time sliding the guide ring along the spindle. CONSTITUTION: Guide rings 6 are provided at two portions inside cylindrical bellows 3 and the hole diameter is slightly increased as compared with a spindle 5 so that the spindle 5 can slide easily. The washer-shaped guide rings 6 can fit into the crest portion of the bellows 3 and at the same time the guide ring 6 and the bellows 3 are adhered and fixed by an adhesive. Also, the guide rings 6 can freely slide along the spindle 5. Then, when a measuring probe 2 contacts an object to be measured and the spindle 5 is pressed and compressed into the inside of a body l, the guide rings 6 slide on the spindle 5 and at the same time the bellows 3 are pushed and compressed. At this time, the guide rings 6 prevent the bellows 3 from contacting the spindle 5, thus preventing buckling from being generated easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detecting device,
In particular, the present invention relates to a structure for preventing a cylindrical bellows, which covers a spindle portion of a long operation displacement detection device, from buckling and being damaged due to expansion and contraction of the spindle.

[0002]

2. Description of the Related Art A spindle having a measuring element at one end is provided movably in the axial direction with respect to a main body, and the dimension of the object to be measured is determined from the displacement of the spindle when the measuring element is brought into contact with the object to be measured. As a device for measuring, for example, a scale having an optical grating is attached to its spindle, and a detector for optically detecting the optical grating of the scale is provided on the main body, and a signal from this detector is processed in a predetermined manner. 2. Description of the Related Art There is known a photoelectric type displacement detection device which detects an axial displacement amount of a spindle.

FIG. 1 is a schematic view of the displacement detecting device. In all of the drawings, the same symbols are assigned to the same components. In the case of the photoelectric displacement detection device as described above, if dust, water droplets, etc. enter the inside of the sliding part of the spindle, an error may occur in reading the scale value, or the sliding part may become worn and the straightness There is a possibility that it will decrease and an error will occur in the detected value.

Therefore, usually, in order to prevent dust and water droplets from entering the inside of the sliding portion of the spindle and to protect the spindle itself from rust and impact, it is covered with a cylindrical bellows 3. There is. Generally, rubber is used for the material of the bellows in consideration of durability and waterproofness.

[0005]

However, in the long-acting displacement detecting device, the spindle is long and the bellows covering it is also long. When a long bellows is frequently extended or contracted, buckling occurs at the center of the bellows, as shown in FIG.
If this is repeated frequently, damage such as tearing or puncture of the bellows will eventually occur. If the fold of the bellows is torn, it is difficult to confirm the damage from the outside, and if left alone, dust and water droplets will enter the displacement detection device and the spindle will rust and become difficult to slide. There is a problem that malfunction or failure of the displacement detection device is likely to occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a long bellows covering a spindle portion of a long-acting displacement detecting device, even if the long bellows is frequently extended or contracted. It is to improve the durability of the displacement detecting device by preventing buckling of the bellows and preventing the bellows from being damaged.

[0007]

In order to achieve the above-mentioned object, the present invention provides a main body and a stylus which is axially movable with respect to the main body and has one end abutting against an object to be measured. And a scale provided at the other end of the spindle and extending along the movement direction of the spindle, an encoder for detecting the relative displacement of the scale and the main body as an electric signal, and a spindle for covering the spindle. In a displacement detection device having a freely extending and contracting cylindrical bellows, a flat washer-shaped guide ring fixed to the inside of the cylindrical bellows is provided, and the spindle penetrates the central opening of the guide ring and The guide ring is configured to slide along the spindle.

[0008]

[Operation] By attaching the guide ring inside the cylindrical bellows that covers the spindle portion of the long-acting displacement detection device,
It is possible to prevent the bellows from buckling when the spindle is contracted, and to prevent the inner side of the bellows from contacting the spindle. Since the material of the bellows is generally rubber, it has a large frictional resistance and is easily damaged if it comes into contact with the spindle. Therefore, only by avoiding the contact between the inner side of the bellows and the spindle, the effect of preventing breakage of the bellows is high.

[0009]

The preferred embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 3 (a), guide rings 6 are arranged at two locations inside the cylindrical bellows 3. The guide ring 6 has a wall thickness of about 0.5 mm. The hole diameter of the guide ring 6 is slightly larger than that of the spindle 5 so that it can slip easily. The washer-shaped guide ring 6 is fitted in the mountain portion of the bellows 3. At the same time, the guide ring 6 and the bellows 3 are adhesively fixed with an adhesive. Further, it can freely slide on the spindle 5. The position and number of the guide rings 6 to be attached are appropriately adjusted depending on the length of the bellows 3 and the maximum length of the spindle 5 that can be compressed.

Next, the behavior of the bellows during actual measurement will be described. When the probe 2 comes into contact with the object to be measured and the spindle 5 is compressed into the main body 1 of the displacement detection device, the guide ring 6 slides on the spindle 5 and the bellows 3 is compressed. The state shown in FIG. At this time, the guide ring 6 prevents the bellows 3 from coming into contact with the spindle 5 and makes buckling less likely.

The guide ring 6 is made of Teflon resin, stainless steel, or the like so that the guide ring 6 slides well with the spindle.

[0011]

As described above, according to the present invention,
Even if the long bellows that covers the spindle part of the long-acting displacement detection device is frequently extended or contracted, it is possible to prevent buckling at the center of the bellows, prevent the bellows from being damaged, and detect the displacement. The durability of the device can be improved. Normally, the bellows was damaged by the expansion and contraction of the spindle about 1 to 2.5 million times, but when the present invention was carried out, the bellows was damaged even after the spindle was expanded and contracted 7.5 million times or more. There was a very remarkable effect of not having it.

[Brief description of drawings]

FIG. 1 is a schematic view of a displacement detection device according to the present invention.

FIG. 2 is a sectional view of a conventional displacement detection device.

FIG. 3 is a sectional view of a displacement detection device according to the present invention.

[Explanation of symbols]

 1 Displacement detector body 2 Probe 3 Bellows 4 Cable 5 Spindle 6 Guide ring 10 Displacement detector

Claims (1)

[Claims] 1. A main body, a spindle movably in the axial direction with respect to the main body, and a spindle having a probe contacting an object to be measured at one end, and a spindle provided at the other end of the spindle. In a displacement detecting device comprising: a scale extending along a moving direction; an encoder for detecting a relative movement displacement amount of the scale and the main body as an electric signal; and a cylindrical bellows extending and contracting so as to cover the spindle. A flat washer-shaped guide ring fixed to the inside of the cylindrical bellows is provided, and the spindle penetrates the central opening of the guide ring and the guide ring slides along the spindle. Displacement detection device characterized by.