JPH038972Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to improvements in dustproof and waterproof mechanisms suitable for length measuring devices, particularly length measuring devices that magnetically detect the relative movement distance of two objects.

BACKGROUND TECHNOLOGY AND PROBLEMS There is a magnetic scale in which a scale made of a magnetic material is embedded in a long and thin member made of a non-magnetic material, which is attached to a fixed part of a machine tool, etc. There is known a length measuring device that includes a magnetic head fixed to a movable part of the machine so as to move along the length of the machine, and magnetically detects the relative movement distance between the fixed part and the movable part.

FIG. 1a is a partially cutaway side view of such a length measuring device, and FIG. 1b is a sectional view, in which 1 shows a magnetic scale and 2 shows a magnetic head. To prevent them from becoming contaminated with cutting fluid or chips, scale 1 is connected to channel 3.
Both ends of the channel 3 are sealed with a scale holding member 9 (only one end is shown) that holds and fixes the scale 1. A sealing material is applied between the scale 1 and the scale holding member 9 to prevent cutting fluid and the like from entering. However, since the magnetic head 2 must be able to move relative to the scale 1, one side of the channel 3 is open;
Its side is covered with a dust cover 4 and dust seals 6 and 7, and the magnetic head 2 is placed on the scale 1.
In order to move the magnetic head 2 against a moving part such as a machine tool, the mounting part that holds and fixes the magnetic head 2 to a head carrier that moves together with a moving part of a machine tool etc. advances between the dust seals 6 and 7 by pushing them apart. It's getting old. Therefore, when the mounting portion passes between the dust seals, a slight gap is created, and a complete dustproof and waterproof effect cannot be obtained. Dust seals 6 and 7 can withstand chips during cutting, but in places where a large amount of cutting fluid is applied, atomized cutting fluid may pass between them and enter the channel. However, it had the disadvantage of causing rust, corrosion, etc.

In particular, recent highly automated and unmanned factories operate all night long, and machine tools use large amounts of highly corrosive water-soluble cutting fluid for long periods of time. Dustproof and waterproof measures for equipment have become an urgent issue.

Purpose of the invention Therefore, the purpose of the present invention is to provide a length measuring device of the type mentioned at the beginning with a completely dustproof and waterproof structure that prevents the intrusion of cutting fluid, chips, etc.

Summary of the invention In order to achieve the above object, the length measuring device according to the invention has two scale holding members that hold and fix both ends of the scale in the scanning direction, the inner end faces facing each other, and the scale that slides on the scale. of a head carrier that holds the head so as to move along and at regular intervals relative to the scale;
The gist is that a bellows is tightly attached between the end face and each opposing end face so as to surround the scale.

Examples Below, the present invention will be explained in more detail using examples with reference to the drawings, but these are merely illustrative, and various modifications and improvements may be made without going beyond the scope of the present invention. Of course.

FIG. 2 is (a) a longitudinal cross-sectional view and (b) a cross-sectional view of the length measuring device according to the first embodiment of the present invention, and FIG.
Reference numbers common to figures refer to the same parts as in FIG. In this embodiment, the magnetic head 2 is housed in a magnetic head case 10 which forms part of a head carrier 8.
The magnetic head case 10 is in a sealed state, and the lead wire coming out of the magnetic head 2 is taken out through a small hole (not shown in the figure). It is blocked by Notches 10A and 9A are provided at both ends of the magnetic head case 10 and on the inside of the scale holding member 9. Bellows 11 and 12 are provided on both sides of the magnetic head case 10 so as to surround the magnetic scale 1 between the mutually opposing end surfaces of the magnetic head case 10 and the scale holding member 9.
are attached, and both ends thereof are engaged with the notches 9A and 10A, and are fixed therein in an airtight manner. Furthermore, an air vent hole 13 is provided through the magnetic head case 10 to facilitate the movement of air within the bellows.
It can move left and right against 2.

The opening of the channel 3 is sealed by dust covers 4 and 5 and dust seals 6 and 7, similar to the device shown in FIG. 1, so that the scale 1 and the magnetic head 2 are double It will be sealed in. Although this sealing is effective against metal powder such as chips, it may not be necessary in some cases.

Figure 3a is a perspective view of the head carrier 8 and bellows 11 and 12 after assembly, with the double arrow 14
indicates the direction of movement of the head carrier 8 and thus of the magnetic head 2. Figure 3b shows the position of the scale 1 and magnetic head 2 compared to Figure 3(a).
FIG. 2 is a perspective view of the apparatus shown in FIG. 1 with parts of bellows 11 and 12 removed.

FIG. 4 is a longitudinal sectional view of a length measuring device according to a second embodiment of the present invention. In this embodiment, the magnetic head is not housed in a magnetic head case, but is fixed to a mounting portion 15 forming a part of the head carrier 8, and notches 15A are formed on both end faces of the mounting portion. It is provided. As in the device shown in FIG. 2, bellows 11 and 12 are attached to both sides of the attachment part 15 between the mutually opposing end surfaces of the attachment part 15 and the scale holding member 9 so as to surround the scale 1. Both ends thereof are engaged with the notches 9A and 15A, and are fixed therein in an airtight manner. It is also the same as in the device shown in FIG. 2 that the air vent hole 13 is provided through the attachment portion 15. That is, in this embodiment, both the scale and the magnetic head are protected by the bellows at the same time.

The length measuring device according to this embodiment has a somewhat simpler structure than the device shown in FIG.
It is not inferior to the latter in terms of dustproof and waterproof effects.

Effects of the invention As explained above, according to the invention, the magnetic head is completely sealed by the magnetic head case, the scale is completely sealed by the bellows, and both the magnetic head and scale are completely sealed by the bellows. It is possible to eliminate inconveniences such as scale and damage and corrosion of the magnetic head due to chips and cutting fluid. Since the bellows can be made of a highly elastic material such as rubber or plastic, it also has the effect of preventing scale vibrations that occur during transportation.

Note that the present invention is of course applicable not only to magnetic scales but also to other scale devices.

[Brief explanation of drawings]

Figures 1a and b are a partially cut-away side view and sectional view of a conventional length measuring device, respectively, and Figures 2 a and b are a vertical sectional view and a respective longitudinal sectional view of a length measuring device according to the first embodiment of the present invention. Cross-sectional view, Figure 3a
3 is a perspective view of the head carrier and bellows after assembly, FIG. 3b is a partially removed perspective view of the device shown in FIG. 3a, and FIG. 4 is a length measuring device according to a second embodiment of the present invention. FIG. 1... Scale, 2... Magnetic head, 3... Channel, 4, 5... Dust cover, 6, 7...
Dust seal, 8...Head carrier, 9...
... Scale holding member, 10 ... Magnetic head case, 11, 12 ... Bellows, 13 ... Air vent hole,
14...Arrow indicating the direction of movement of the magnetic head, 15
...Mounting part, 9A, 10A, 15A...Notch part.

Claims (1)

[Scope of utility model registration request] The inner end surfaces of two scale holding members that hold and fix both ends of the scale in the scanning direction, and the head slides on the scale and moves along the scale at a constant interval relative to the scale. A measuring device for detecting the relative movement distance of two objects, characterized in that a bellows is attached between the end surface and each opposing end surface of the head carrier to surround the scale. Long device.