JPH052809Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a linear scale used to detect the position (movement amount) of a linearly moving member (object) in position control of an injection molding machine, etc. .

(Problems to be solved by the prior art and the invention) When automatically controlling injection molding machines, various machine tools, assembly machines, etc., it is necessary to detect the position (travel amount) of moving parts, which is called a linear scale. Several things have been proposed.

Figure 8 shows the schematic configuration of a conventional linear scale using a rotary encoder.
A rotary encoder 31 with a gear 32 attached to a rotating shaft 31a is fixed to the member A side using a mounting bracket 34 or the like, and a rail 33 having a rack 32a is fixed to the member B side that moves linearly relative to the member A. , meshing the gear 32 and the rack 33a,
The relative movement between members A and B was converted into rotation of a rotary encoder 31, and a signal corresponding to the amount of movement was obtained from the rotary encoder 31.

Incidentally, since this type of linear scale is often installed in a limited space in mechanisms such as injection molding machines, various machine tools, and assembly machines, misalignment may occur during installation. However, in the conventional linear scale described above, if the gear 32 and the rack 33a are separated, the gear 32 and the rack 33a spin idly and do not indicate the correct position, or conversely, if the gear 32 and the rack 33a are too close together, the gear 32 and the rack 33a become too close together. The rack 33a would creak, preventing smooth engagement, and the rotary shaft 31a of the rotary encoder 31 would sometimes become bent, rendering it inoperable. Furthermore, even if the mounting position is accurate, foreign objects may get caught between the gear 32 and the rack 33a. For example, when a nut or screw is caught, teeth may be chipped in the gear 32 or the rack 33a. The rotating shaft 31a of the rotary encoder 31 sometimes bends or breaks.

(Purpose of the invention) The present invention was proposed in view of the above points, and its purpose is to improve the close contact between the gear and the rack in a linear scale using a rotary encoder, gears, and rack. ,
The purpose is to prevent damage to various parts by preventing large loads from being applied even when foreign objects are caught.

(Means for Solving the Problems) In order to achieve the above object, the present invention aims to connect a case equipped with a rotary encoder in which a gear is attached to a rotating shaft and a rail on which a rack is formed relative to each other and in a straight line. The gear and the rack on the rail are engaged with each other, and the relative movement between the objects is converted into rotation of the rotary encoder. In a linear scale configured to obtain a signal, the rotary encoder is rotatably supported in a case at one end separated from the rotary shaft in the longitudinal direction, and the other end is elastically held within the case. The gist of the linear scale is that the gear is pressed against the rack within a predetermined load range.

(Function) The present invention elastically holds the rotary encoder to which the gear is attached and easily presses it within a predetermined load range, thereby improving adhesion and preventing damage due to excessive load.

(Example) Hereinafter, the present invention will be described in detail with reference to drawings showing examples.

1 to 3 show a first embodiment of the linear scale according to the present invention, and FIG. The figure is an exploded view of the components inside the case 4, and FIG. 3 is a diagram showing the state in which the gear 2 is meshed with the rail 3 on which the rack 3a is formed.

In FIGS. 1 and 2, the rotary encoder 1 is fixed to a movable plate 7, and a gear 2 is attached to a rotating shaft 1a protruding from the movable plate 7. Further, a cylindrical shaft 8 is erected at the end of the movable plate 7 on the inside of the case, and the cylindrical shaft 8 and the movable plate 7 are installed between both ends of the bent part of the shaft holding fitting 5 fixed to the inner wall of the case 4. The cylindrical shaft 8 and the movable plate 7 are inserted from the shaft holding fitting 5.
The shaft holding pin 11 is fitted into the hole, and the retaining fittings 12 are attached to the grooves at both ends of the shaft holding pin 11, so that the movable plate 7 is rotatably supported. A spring 1 is also provided between the L-shaped fitting 6 fixed to the inner wall of the case 4 and the L-shaped fitting 9 fixed to the back surface of the movable plate 7.
0 is arranged, the movable plate 7 is held elastically and always pressed downward in FIG.
The gear 2 is pressed downward.

Therefore, when the rack 3a of the rail 3 and the gear 2 are meshed together as shown in FIG. 3, the repulsive force of the spring 10 presses the gear 2 against the rack 3a, so the adhesion between the two is good and there is no installation error. This means that it will not squeak or separate even if it gets wet.
Furthermore, even if a foreign object such as a screw or nut gets caught between the rack 3a and the gear 2, the movable plate 7 will not move upwards significantly and an excessive load will not be applied. Also, bending and breaking of the rotating shaft 1a of the rotary encoder 1 can be prevented.

Next, FIGS. 4 and 5 show the second embodiment, and FIG. 4 shows the rotary encoder 1.
A view of the case 13 provided with the gear 2,
FIG. 5 shows a state in which the gear 2 is meshed with the rail 3 on which the rack 3a is formed.

In FIGS. 4 and 5, the rotary encoder 1 is fixed to a movable plate 14, and a gear 2 is attached to a rotating shaft 1a protruding from the movable plate 14. The movable plate 14 is rotatably attached to the front surface 13a of the case 13 by a cylindrical shaft 15 and a shaft holding pin 16, and the L-shaped bent portion 14a is pressed by a spring 18 from an L-shaped metal fitting 17 fixed to the case 13. It is becoming more and more like this.

On the other hand, the rail passing holes 13 on both sides of the case 13
Pass the rail 3 into the case 13 from b, and
The lower surface of the case 13 is received by guide rollers 21 and 22 provided on the front surface 13a of the case 13, and guide gears 19 and 20 are provided above the guide rollers 21 and 22 in opposing positions.

When the rack 3a of the rail 3 and the gear 2 are meshed together as shown in FIG. Therefore, the adhesion between the two is good, and even if there is an installation error, there will be no creaking or separation, and even if a foreign object such as a screw or nut gets caught between the rack 3a and the gear 2, the movable plate 14 will move upward significantly. Since an excessive load is not applied, it is possible to prevent the gear 2 and the rack 3a from chipping, and the rotating shaft 1a of the rotary encoder 1 from bending or breaking. Moreover, in this embodiment, since the rail 3 is passed through the inside of the case 13, injection molding machines and various machine tools, etc.
It has the advantage of being easy to attach to assembly machines and the like.

Next, FIGS. 6 and 7 show an example of a means for fixing the end of the rail 3, which is designed to absorb mounting errors of the rail 3 without reducing the accuracy of the reference position. . That is, the connecting shaft 3b extending from the end of the rail 3 is connected to the connecting fitting 2.
After passing through the hole 23a of No. 3, the spring 25 is loaded, the washer 26 is arranged, the retaining fitting 27 is attached, and the end of the connecting shaft 3b is inserted into the recess 23 of the connecting fitting 23.
b, so that even if the rail 3 is slightly misaligned, the end of the connecting shaft 3b is allowed to play within the recess 23b of the connecting fitting 23, thereby absorbing the misalignment.

(Effects of the invention) As described above, in the present invention, a case equipped with a rotary encoder in which a gear is attached to a rotating shaft and a rail on which a rack is formed are moved relative to each other in a straight line. attached to each object, meshing the gear with the rack on the rail, converting relative movement between the objects into rotation of the rotary encoder, and obtaining a signal corresponding to the amount of movement from the rotary encoder. In the linear scale, the rotary encoder is rotatably supported in the case at one end separated from the rotary shaft in the longitudinal direction, and the other end is elastically held in the case, and the gear is Since the rack is pressed within a predetermined load range, even if there is an installation error or a foreign object gets caught, the gear will move appropriately and no excessive load will be applied. This has the effect of preventing damage such as, etc., and preventing displacement of the rack in the longitudinal direction.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of the linear scale of the present invention. Figure 1 is a view of the case equipped with a rotary encoder viewed from the gear side, and Figure 2 is a view of the case. FIG. 3 is a diagram showing a state in which gears are meshed with a rail with a rack formed therein, FIGS. 4 and 5 are views showing the second embodiment, and FIG. Figure 4 is a view of the case equipped with a rotary encoder viewed from the gear side, Figure 5 is a diagram showing the gear meshed with a rail with a rack, and Figures 6 and 7 are views of the end of the rail. FIG. 8 is a diagram showing a schematic configuration of a conventional linear scale. 1... Rotary encoder, 1a... Rotating shaft, 2... Gear, 3... Rail, 3a... Rack, 4... Case, 5... Shaft holding metal fitting, 6, 9...
... L-shaped metal fitting, 7 ... Movable plate, 8 ... Cylindrical shaft, 10 ... Spring, 11 ... Shaft holding pin,
12...Retaining pin.

Claims (1)

[Claims for Utility Model Registration] A case equipped with a rotary encoder in which a gear is attached to a rotating shaft and a rail on which a rack is formed are respectively attached to two objects that move linearly relative to each other, In the linear scale, the linear scale engages with a rack on the rail, converts relative movement between the objects into rotation of the rotary encoder, and obtains a signal according to the amount of movement from the rotary encoder, wherein the rotary encoder is rotatably supported in a case at one end separated from its rotation axis in the length direction of the rack, and the other end is elastically held within the case, and the gear is applied with a predetermined load to the rack. A linear scale that is characterized by being pressed within a range.