JP2510260Y2 - Length measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a length measuring device having a structure in which a linear scale and a detection head are housed inside a scale unit, and particularly to a liquid or gas inside the scale unit. -It relates to the improvement of the length measurement device that prevents harmful substances such as steam and powder particles from entering the scale unit from the outside.

[Prior Art] For example, in a machine tool or the like, when measuring a moving distance of a bed on which a work is placed with respect to a base, for example, a linear scale is attached to a movable bed, and a linear scale is attached to a fixed base. A length measuring device is often used in which a detection head is attached so as to be movable relative to the table, and the scale of the scale that moves together with the table is read by the detection head. In such a length measuring device, there are problems that oil droplets and dust are likely to adhere to the scale depending on the working environment, and measurement errors are likely to occur under the influence of such an environment. As a solution to such a problem, a length measuring device having a structure in which a linear scale and a detection head are housed in a case has been proposed. Figures 8-10
The figure shows a length measuring device having such a structure disclosed in Japanese Utility Model Laid-Open No. 60-143308. As shown in these figures, a linear scale 102 is provided inside a holder 101 which is a box-shaped case. Although not shown, a detection head is movably provided on the linear scale 102, and an arm provided on the detection head is a holder 101.
It will be connected to the external object to be measured through the lip seal 103. A single outlet 105 is formed in the center of the lid 104 that closes one end of the holder 101. A tube 1 for supplying gas from the outside to the outlet 105.
06 is connected, and by supplying gas into the holder 101, the pressure inside the holder 101 is made higher than the external pressure so that dust and the like do not enter the holder 101. Further, a shield plate 107 for dividing the gas supplied from the tube 106 is provided on the inner surface side of the holder 101 facing the outlet 105. This shield 107
Has a hat shape having a plate portion 108 that is perpendicular to the direction in which the gas blows out. The plate portion 108 diverts the gas in two directions, and the gas discharged from the blowout port 105 is applied to both sides of the linear scale 102. It is a member that allows to flow in parallel with.

[Problems to be Solved by the Invention] The above-described conventional length measuring device has the following problems.

Since the gas supplied into the holder 101 branches in two directions, it is difficult to evenly diffuse the gas in the holder 101.

The gas flow changes depending on the mounting direction of the shielding plate 107.

Since the flow of gas is directional, if the opening of the holder 101 is near the outlet 105, a negative pressure for sucking the outside air is generated, and a harmful substance may enter the holder 101.

Since the shielding plate 107 having the plate portion 108 that is perpendicular to the blowing direction is provided in front of the air outlet 105, the thrust force of the gas in the forward direction is almost lost, and it is difficult to supply the gas to the distant place.

[Means for Solving the Problems] In the length measuring device of the present invention, air is introduced into the scale unit through a nozzle so that the atmospheric pressure in the scale unit becomes positive with respect to the external pressure. In the length measuring device, a holder having a through hole, a first flange portion provided at a tip end portion of the holder and having a front surface substantially orthogonal to a length direction of the scale unit, and the through hole are continuously provided. It has an enlarged diameter portion formed by opening on the front surface of the first flange portion, and a nozzle body attached to the holder. The nozzle body is provided at the tip of the tube portion, which is inserted into the through hole of the holder, and discharges the air introduced thereinto from the nozzle hole provided on the outer peripheral surface into the expanded diameter portion. And a second flange that faces the first flange and that has a blowout surface that is inclined forward with respect to the front surface of the first flange. The first flange is configured to be dispersed and discharged between the direction along the front surface of the first flange and the direction along the outlet surface of the second flange.

[Operation] The gas blown out from the plurality of openings spreads in multiple directions, and blows forward with sufficient thrust at the outlet surface inclined with respect to the length direction of the scale unit. Therefore, the gas is evenly diffused in the scale unit and can reach far enough.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS.

First, the nozzle 2 included in the length measuring device 1 of this embodiment will be described with reference to FIGS. 1 to 3. Reference numeral 3 in the drawing is a substantially tubular holder in which a through hole 3a for holding a nozzle body 4 described later is formed. On the outer peripheral surface of the rear end portion of the holder 3, a screw portion 6 for attaching to a scale unit 5 described later is provided, and a flange portion 7 as a first flange portion is formed at the tip end portion thereof. The portion of the through hole 3a that is open to the flange portion 7 is an enlarged diameter portion 8 having a larger inner diameter than the other portions. Next, the nozzle body 4 is attached to the holder 3. The nozzle body 4 has a tube portion 9 having an outer diameter equivalent to the small inner diameter of the through hole 3a. Then, the pipe portion 9 is inserted into the through hole 3a from the flange portion 7 side, and the nozzle body 4 and the holder 3 are fixed to each other with their rear end faces aligned. Further, a gas introduction hole 10 is formed in the tube portion 9. The introduction hole 10 is opened at the rear end surface of the tube portion 9 and is radially formed with respect to the axis on the peripheral surface of the tube portion 9 facing the expanded diameter portion 8 of the through hole 3a. It is opened with four nozzle holes 11. Next, the nozzle body 4
A flange portion 12 as a second flange portion is formed at the tip portion of the pipe portion 9. Flange portion 7 of the holder 3
The air outlet surface 13 of the flange portion 12 facing the above has a shape inclined with respect to the axis of the tube portion 9, such as the peripheral surface of a truncated cone.

Next, the length measuring device 1 incorporating the nozzle 2 as described above
This will be described with reference to FIGS. 4 to 7.

As shown in FIGS. 4 to 6, the base 14 and the cover 15
A scale 16 having scales in the longitudinal direction is fixed inside the scale unit 5 consisting of. The scale unit 5 is attached to one of the objects to be measured. Further, between the base 14 and the cover 15 and below the scale 16, there is provided an opening groove extending in the longitudinal direction. The opening groove has a flexible lip seal 17,1.
7 is provided to seal the inside of the scale unit 5 from the outside. Then, as shown in FIG. 7, the scale 16 is provided with a detection head 18 which moves in the longitudinal direction using the scale 16 as a guide and reads the scale.
The detection head 18 is interlockingly connected to the other object to be measured outside the scale unit 5 via a link 19 projecting to the outside from between the lip seals 17, 17.

Next, a mounting hole 14a is formed in the side end surface of the base 14 of the scale unit 5. The rear end portion of the nozzle 2 is inserted into the mounting hole 14a from the inside of the scale unit 5, and the flange portion 7 of the holder 3 is locked to the inner wall surface of the base 14. A joint 20 is screwed into the threaded portion 6 of the holder 3 protruding from the mounting hole 14a to the outside of the scale unit 5, and the nozzle 2 is fixed to the scale unit 5. Here, the axis of the introduction hole 10 of the nozzle 2 is substantially aligned with the longitudinal direction of the scale 16, that is, the longitudinal direction of the scale unit 5. The joint 20 has a tube joint 22 having a fixing nut 21.
Further, a tube 23 for gas supply is inserted into the tube joint 22 and fixed by a fixing nut 21.

 Next, the operation of the above configuration will be described.

When air is supplied from the tube 23 with a predetermined pressure, the air that has entered the introduction hole 10 of the nozzle 2 is discharged from the nozzle body 4
Is blown out from each of the nozzle holes 11 arranged at equal intervals in the radial direction on the peripheral surface of the. The blown air is used for the expanded diameter portion 8 of the holder 3.
It hits the inner peripheral wall of and expands as a whole in the enlarged diameter portion 8 as shown by the arrow in FIG. Then, the air spreads radially outward from the gap between the flange portion 12 of the nozzle body 4 and the flange portion 7 of the holder 3, as shown by the arrows in FIGS. 1 and 2. Here, the air blown out from the enlarged diameter portion 8 is guided along the front surface of the first flange portion 7 in a direction substantially orthogonal to the length direction of the scale unit,
Although it hits the air outlet surface 13 of the nozzle body 4, the air outlet surface 13 is not perpendicular to the longitudinal direction of the scale unit 5 and has an inclination of an appropriate angle, so that the air blown out is vigorous. Without being lost, it is diffused forward with sufficient thrust.

That is, according to the present embodiment, the air supplied into the scale unit 5 diffuses uniformly in the scale unit 5 without causing a biased flow at a specific position, and the other end of the scale unit 5 is also dispersed. Can reach the department enough. Therefore, the inside of the scale unit 5 is maintained at a sufficient positive pressure with respect to the outside. For this reason, the lip seal 1
There is no danger of foreign matter entering the scale unit 5 from between 7,17, and even if the opening groove is provided near the nozzle 2, no local negative pressure is generated, so foreign matter and the like will be present together with the outside air. Never inhale. Further, since the air is blown out radially from the nozzle 2, even if the mounting posture of the nozzle 2 with respect to the scale unit 5 changes, the air flow inside the scale unit 5 does not change.

In the embodiment described above, the outlet surface 13 is formed of the peripheral surface of the truncated cone, but the shape of the outlet surface 13 is not limited to this. That is, in the above-described embodiment, as shown in FIG. 2, the surface shape of the cut surface passing through the axis is a straight line inclined with respect to the longitudinal direction of the scale unit 5. The surface shape may be a curve that can guide the blown air obliquely forward. Further, the number of nozzle holes 11 is not limited to four, and can be set to any number as needed.

[Advantages of the Invention] The length measuring apparatus of the present invention includes a first flange portion having a front surface that is substantially orthogonal to the length direction of the scale unit, and a first flange portion.
Air having a second flange having an outlet surface inclined forward with respect to the front surface of the flange and an expanded diameter portion opening to the front surface of the first flange portion, and air released forward from the expanded diameter portion. In the direction along the front surface of the first flange and the second
It is possible to disperse and discharge the air between the directions along the outlet surface of the flange, and to evenly diffuse and supply the air into the scale unit. Therefore, according to the present invention,
The gas is blown out radially with respect to the longitudinal direction of the scale,
At the same time, it is evenly diffused inside the scale unit. As a result, even if an opening to the outside is provided in a part of the scale unit, especially in the vicinity of the nozzle, a part of the gas blown out radially is blown out from the opening, so that the gas from the outside, etc. Will never invade. Further, since the blowing direction of the gas is radial with respect to the longitudinal direction of the scale, the thrust force to the front of the gas is sufficiently secured, so that the gas can be swiftly supplied to the long scale and the scale unit. It became possible to supply. Furthermore, since the gas is blown out radially, there is no change in the characteristics of the device due to the nozzle mounting direction or the like.

[Brief description of drawings]

1 is a front view of a nozzle according to an embodiment of the present invention, FIG. 2 is a sectional view of the nozzle, FIG. 3 is a sectional view taken along the line III-III of FIG. 2, and FIG. FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4, and FIG. 6 is a partially cutaway bottom view of the length measuring apparatus of the embodiment. 7 and 8 are cross-sectional views taken along the line V-V of the length measuring device provided with a detection head, FIG. 8 is a side view of the conventional length measuring device, and FIG. 9 is the same as the conventional length measuring device. A sectional view and FIG. 10 are sectional views taken along the line XX in FIG. 1 ... Length measuring device, 2 ... Nozzle, 5 ... Scale unit, 11 ... Nozzle hole as opening, 13 ... Air outlet face.

Claims (1)

(57) [Scope of utility model registration request] 1. A length measuring device in which air is introduced into the scale unit through a nozzle so that the atmospheric pressure in the scale unit is positive with respect to the external pressure, and a holder having a through hole, A first flange portion provided at the tip of the holder and having a front surface that is substantially orthogonal to the length direction of the scale unit, and formed to open to the front surface of the first flange portion continuously from the through hole. The expanded diameter portion, a pipe portion that is inserted into the through hole of the holder and discharges the air introduced into the inside from the nozzle hole provided on the outer peripheral surface into the enlarged diameter portion, and the pipe portion is provided at the tip of the pipe portion. And a second flange that faces the first flange and has a blowout surface that is inclined forward with respect to the front surface of the first flange, and discharges the air released forward from the expanded diameter portion to the first flange. 1 along the front of the flange Direction and a direction along the outlet surface of the second flange, the nozzle main body disperses and discharges the lengthwise measuring device.