JPS61243309A - Displacement measuring instrument - Google Patents

Abstract

PURPOSE:To prevent oil, dust and the like from invading the inside of a hollow casing by forming a labyrinthine groove wherein a connecting shaft and the side surface of an opening loosely fit each other in a longitudinal direction, said groove being formed between the connecting shaft and the side surface of the opening. CONSTITUTION:A hollow casing 1 and a slider 3 are fixed to the stationary and movable portions, respectively, of a machine tool or the like. When the slider 3 is displaced relative to the hollow casing 1, although the outside and inside of the hollow casing 1 are isolated from each other by a connecting shaft 5 and sealing members 19 and 20 anyhow, some gap is produced. However, since the connecting shaft 5 and a penetrated portion 18 loosely fit each other and a labyrinthine groove is formed between an opening 2 and a hollow space 4, a labyrinthine structure so formed prevents the invasion of dust and oil therethrough and further the invasion into the hollow space 4 is surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a displacement measuring device that is attached to a machine tool or the like and used to detect and control relative movement of moving members.

(Background of the invention) Conventionally, this type of displacement measuring device was developed by Japanese Patent Publication No. 56-27803
There are things shown in @.

An example of such a displacement measuring device is schematically shown in FIG. This figure is a sectional view, and the hollow case 1 is shown in the longitudinal direction (fourth direction).
An opening 2 is formed having a substantially rectangular hollow cross section along the direction perpendicular to the plane of the drawing, and extending substantially in length along one side in the longitudinal direction. The slider 3 is the opening 2 of the hollow case 1
A connection 1JIll1 extending through the hollow part 4 of the
5, and is configured to move relative to the longitudinal direction of the hollow case 1.

Flexible sheet-like members 6 and 7 are fixed to the hollow case 1 from opposite sides of the opening 2 so as to cover the opening 2, and the sheet-like members 6 and 7 form a so-called ripple seal. There is. Therefore, the connecting shaft 5 is sandwiched between the sheet-like members 6 and 7, and moves in the longitudinal direction within the opening 2 so as to cut between the sheet-like members 6 and 7, respectively.

A position detection mechanism for detecting the amount of relative movement between the hollow case 1 and the slider 3 is installed in the hollow part 4 of the hollow case 1. That is, in the hollow part 4 of the hollow case 1, a scale member 8 made of a transparent flat plate such as a crow, which extends in a direction perpendicular to the paper surface of FIG. 4, is fitted into a groove in the hollow case 1 and fixed with a rubber rod 9. It's been done. A scale is drawn on one side of the scale member 8 along the hollow case 1. A connecting shaft 5 extending from the slider 3 extends to the vicinity of the scale member 8, and a reading mechanism of a position detecting mechanism is attached to the tip end of the connecting shaft 5. That is, at the tip of the scale member 8, a reading member 10 having a cross-sectional shape is mounted on the scale by sliders 11 and 12 that contact two surfaces perpendicular to the scale member 8, and rollers 13 biased by springs. Part 8
The reading member 10 is always pressed against the scale member 8.
are guided by. Further, the reading member 10 is rotatably attached to the connecting shaft 5, and the light emitting element 14 is placed on one side with the graduation surface of the scale member 8 in between, and the index 15 and the light receiving element 16 are placed on the other side on the right side. Ru.

In the displacement measuring device configured in this way, the hollow case 1 is fixed to one of a pair of objects to be measured that move relatively, and the slider 3 is fixed to the other. The case 1 and the slider 3 move relative to each other, and the reading member 10 provided with the index 151, the light emitting element 14, and the light receiving element 16 also moves relative to the scale member 8.

At this time, a sinusoidal signal is generated from the light receiving element 16 in accordance with the difference in light transmission between a portion of the scale member 8 that does not transmit light, such as a black line, and a portion that transmits light without a black line. The relative position of the object to be measured can be detected by converting this signal into a rectangular signal and counting it.

(Problem to be solved by the invention) However, in a displacement measuring device having such a structure, when the hollow case 1 and the slider 3 move relative to each other, the joint between the sheet members 6 and 7 is forced by the connecting shaft 5. Since the connecting shaft 5 is opened outward, a gap is created at both ends of the connecting shaft 5 so that the inside and outside of the hollow case 1 communicate with each other. For this reason, for example,
When the displacement measuring device is used as a feedback device for a numerical value υj111 machine tool, etc., it will be placed in an atmosphere where cutting fluid is scattered, so foreign substances such as oil and dust may enter the hollow case 1 through the gap. , this is scale member 8
There is a problem in that the particles adhere to the light emitting element 14 or the light receiving element 16, resulting in deterioration of measurement accuracy.

Note that this problem is not limited to the photoelectric displacement measuring device described above, but also applies to displacement measuring devices based on the principle of magnetic isometry.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems in the prior art. An object of the present invention is to provide a displacement measuring device that can prevent the intrusion of foreign substances.

(Summary of the Invention) In order to achieve this object, the present invention includes a hollow case that incorporates a scale member and has an opening in the longitudinal direction of the scale member, and a hollow case that is inserted into the hollow case through the opening and has a In a displacement measuring device having a slider having a reading section for reading the scale of a scale member, and a pair of flexible members provided facing each other so as to cover the opening, the connecting shaft and a side surface of the opening. The technical point is that a labyrinth-shaped groove is formed between the connecting shaft and the side surface of the opening in which the connecting shaft and the side surface of the opening loosely fit into each other along the longitudinal direction.

(Example) Hereinafter, one embodiment of the present invention will be briefly described with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention.

In the hollow case 1, an opening 2 that penetrates to the hollow part 4 of the hollow case 1 is formed over substantially the entire length along the longitudinal direction.

The slider 3 integrally has a connecting shaft 5 extending through the opening 2 of the hollow case 1 and into the hollow part 4 thereof, and is configured to move relative to the hollow case 1 in the longitudinal direction.

A position detection mechanism for detecting the amount of relative movement between the hollow case 1 and the slider 3 is installed in the hollow portion 4 of the hollow case 1 . That is, in the hollow part of the hollow case 1, a scale member 8 made of a transparent parallel plate made of glass or the like is fitted into a groove in the hollow part 4 and fixed via a rubber rod 9 in a direction perpendicular to the paper plane of FIG. A scale is drawn on one side of the scale member 8 along the longitudinal direction. A connecting shaft 5 extending from the slider 3 extends to the vicinity of the scale member 8, and a reading mechanism 17 is fixed to the tip thereof, similar to the position detecting mechanism shown in FIG. 4. That is, as shown in FIG. 4, the reading mechanism 17 is composed of a reading member 10.1 attached to the connecting shaft 5, movers 11, 12), rollers 13, a light emitting element 14, an index 15, and a light receiving element 16. Light emitted from the element 14 passes through the scale member 8 and the index 15 and is received by the light receiving element 16.

As shown in FIG. 1, the connecting shaft 5 has a bent cross-sectional shape with a plurality of angle parts, and in order to make the connecting shaft 5 movable in the longitudinal direction along the opening 2, An opening 2 connecting the outside of the hollow case 1 and the hollow part 4
The penetrating portion 18 is formed to have a hollow cross-sectional shape bent according to the cross-sectional shape of the connecting shaft 5, and the connecting shaft 5 is loosely fitted with a predetermined gap.

As a result, a labyrinth-like groove is formed between the connecting shaft 4 and the penetrating portion 18.

Flexible sheet members 19 and 20 are fixed to the hollow case 1 facing each other so as to cover the opening 2 from both sides of the opening 2 to form a so-called ripple seal. Sheet member 21 which also has flexibility on the 4th side.
22 are fixed facing each other to form a so-called ripple seal.

Note that the width of the labyrinth-shaped groove formed on the side surface of the connecting shaft 5 and the penetrating portion 18 is such that when the reading mechanism 17 is guided by the scale member 8 and moves, the guide surface is inclined, etc. As a result, the side surface of the penetrating portion 18 also acts as a limit wall for the lateral movement of the connecting shaft 5.

With such a configuration, for example, if the hollow case 1 is fixed to a fixed part of a machine tool and the slider 3 is fixed to a movable part, and the slider 3 is moved relative to the hollow case 1,
5 connecting shafts and 1 sealing member.

20, the outside and the inside of the hollow case 1 are temporarily cut off, but as in the conventional case, it is inevitable that a slight gap will occur. However, since a labyrinth-like groove is formed between the opening 2 and the hollow part 4 due to the loose fit between the connecting shaft 5 and the penetrating portion 18, this labyrinth structure prevents the intrusion of dust and oil, and furthermore,
Intrusion into the hollow portion 4 is reliably prevented by the inner sheet-like members 21 and 22.

FIG. 2 is a sectional view showing another embodiment of the present invention. Scale member 8. The device detection mechanism composed of the rubber rod 9 and the reading mechanism 17 is constructed in the same manner as shown in FIG. 1, and therefore its explanation will be omitted.

The connecting shaft 5 has a larger number of angle portions to form folded portions 23 than in the case of FIG. A first oil barrier 24 is formed in the penetrating portion 18 and protrudes so as to loosely fit into the recess formed by the folded portion 23 . Furthermore, a second oil barrier 25 is formed on the hollow part 4 side of the hollow case 1.

Therefore, a labyrinth-shaped groove is formed by the loose fit between the connecting shaft 5 and the penetrating portion 18.

Flexible sheet members 19 and 20 are fixed to the opening 2 of the hollow case 1 so as to cover the opening 2 and face each other.

Note that the width of the labyrinth-shaped groove formed on the side surface of the connecting shaft 5 and the penetrating portion 18 is determined by the width of the labyrinth-shaped groove formed on the side surface of the connecting shaft 5 and the penetrating portion 18 when the reading mechanism 17 moves while being guided by the scale member 6, as shown in the embodiment of FIG. The allowable range of movement is determined when the slider 3 is tilted with respect to the hollow case 1 and moved horizontally due to the guide surface being inclined, etc., and as a result, the side surface of the penetrating portion 18 will prevent the lateral movement of the connecting shaft 5. It also acts as a limiting wall.

In this way, the oil barrier 24.25 is formed in the penetrating portion 18,
Since a labyrinth-shaped groove is formed with the folded portion 23 of the connecting shaft 5, it is possible to reliably prevent cutting oil and the like from entering the inside of the hollow case 1 even when used in a numerically controlled machine tool or the like.

In addition, among the labyrinth-shaped grooves formed between the connecting shaft 5 and the penetration part 18, the groove leading to the hollow part 4 side is located at a higher position than the groove leading to the opening 2 side. Even if oil or the like enters through the gap between the sheet members 19 and 20, it will not accumulate to a height that exceeds the groove on the hollow part 4 side, and the sheet member 1 will re-enter.
It will be discharged to the outside through the gap at 9.20.

Furthermore, since the labyrinth-shaped groove can prevent oil from entering, it is possible to reduce the number of sheet members, and the contact friction between the connecting shaft and the sheet member can be reduced. Therefore, it is advantageous when used in a machine or the like in which the sliding resistance of the slider must be reduced.

FIG. 3 is a sectional view showing still another embodiment.

Note that the position detection mechanism has the same configuration as in FIGS. 1 and 2, so a description thereof will be omitted.

Oil barriers 26 and 27 alternately protrude inward from both sides of the side surface of the penetrating portion 18 of the hollow case 1, and the connecting shaft 5 is provided with oil barriers 26 and 27 so as to surround these barriers 26 and 27 at predetermined intervals. Recessed fitting portions 28 and 29 are formed in and exposed. Then, the oil barrier 26.27 and the recessed fitting portions 28.29 fit loosely, respectively.
A labyrinthine groove is formed between the opening 2 and the penetrating portion 18 of the hollow portion 4, so that the hollow case 1 and the connecting shaft 5 can move relative to each other in the longitudinal direction of the opening 2.

In addition, as shown in the embodiments of FIGS. 1 and 2, the connection fII
When the reading mechanism 17 is guided by the scale member 6 and moves, the width of the labyrinth-like groove formed on the side surface of the II 5 and the penetrating portion 18 is determined by the width of the labyrinth-like groove formed by the side surface of the II 5 and the penetrating portion 18. The permissible range of movement when the slider 3 tilts and moves horizontally is determined, and as a result, the penetrating portion 1
The side surface of 8 also acts as a limiting wall for the lateral movement of the connecting shaft 5.

In this way, since the oil barrier 26, 27 and the recessed fitting portions 28 and 29 form a maze-like groove, intrusion of oil, dust, etc. from the outside can be reliably prevented.

In addition, among the labyrinth-shaped grooves formed between the connecting shaft 5 and the penetration part 18, the groove leading to the hollow part 4 side is located at a higher position than the groove leading to the opening 2 side. Even if oil or the like enters through the gap between the sheet members 19 and 20, it will not accumulate to a height that exceeds the groove on the hollow part 4 side, and the sheet member 1 will re-enter.
It will be discharged to the outside through the gap at 9.20.

Furthermore, since the labyrinth-shaped groove can prevent oil from entering, it is possible to reduce the number of sheet members, and the contact friction between the connecting shaft and the sheet member can be reduced. Therefore, it is advantageous when used in machines, etc. in which the sliding resistance of the slider must be reduced.

Note that the shapes of the grooves in each of the above embodiments can be modified in various ways, and are not limited to the shapes shown here.

Furthermore, although each embodiment has been described using an optical displacement measuring device, other methods such as a magnetic method may be used.

(Effects of the Invention) As explained above, according to the present invention, it is possible to prevent foreign substances such as oil and dust from entering into the hollow case from the outside.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is a sectional view showing another embodiment of the invention, Fig. 3 is a sectional view showing another embodiment of the invention, and Fig. 4 is a sectional view showing a conventional FIG. 2 is a cross-sectional view showing the configuration of a displacement measuring device. 1: Hollow case 2: Opening 3 Nislider 4: Hollow part 5: Connecting shaft 6, 7.19.20.21.22: Sheet member 8 Niscale member 9: Rubber rod 10: Reading member 17: Reading mechanism 181 penetration part 23: Turned part 24, 25.26.27: Oil dike 28.29: Recessed part

Claims (2)

[Claims] (1) A hollow case containing a scale member and having an opening in the longitudinal direction of the scale member, and a reading mechanism that is inserted into the hollow case through the opening and reads the scale of the scale member at the tip. a connecting shaft having a slider fixed to the end thereof; and flexible ripple seals facing each other so as to cover the opening from both sides of the opening; and the connecting shaft, comprising a labyrinth-shaped groove formed by loosely fitting the hollow case and the connecting shaft along the longitudinal direction of the opening. (2) In the displacement measuring device according to claim 1, the labyrinth-shaped groove is formed in the hollow space in a direction perpendicular to the scale surface of the scale member and in a direction perpendicular to the direction and the scale surface. A displacement measuring device characterized by having a predetermined gap interval that regulates the amount of relative movement between the case and the connecting shaft.