JPS608173B2 - Stop position detection device for moving table in machine tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the stop position of a moving table in a machine tool.

Conventionally, this type of device has provided a limit switch that also serves as a stopper on the movement line of the movable table, and the stop position of the movable table has been detected by this limit switch.

However, when a limit switch is disposed in a drive device of a machine tool, there is a risk that the electric cord of the limit switch may be caught by a moving table or other moving body, causing the cord to be disconnected. The present invention aims to eliminate the above-mentioned drawbacks by making it possible to locate the limit switch at a distance from the drive device.

Still another main object is to provide a stop position detection device for a movable table that does not malfunction even if a surge pressure occurs in a hydraulic circuit. The configuration of the present invention will be described in detail below with reference to embodiments shown in the accompanying drawings.

1 is a hydraulic cylinder that drives a moving table 2 or a carriage of a machine tool, and a piston rod 3 is connected to the moving table 2 or carriage.

4 is a solenoid operated switching valve, 5 is a hydraulic pump, 6 and 7 are fluid passage pipes, and single acting cylinders 10 and 11 are connected to the pipes 6 and 7 via branch pipes 8 and 9.

Piston rods 12, 1 of the single acting cylinders 10, 11
Switch operation pieces 14, 15 are attached to the switch 3, and limit switches 16, 17 and 18, 19 are opposed to the upper and lower limits of the movement range of the operation pieces 14, 15, respectively.
The switch operation piece 14 constitutes a first oil pressure detection moving body 14, and the switch operation piece 15 constitutes a second oil pressure detection movement body 15. The piston rods 12, 13
is biased in the return direction by a coil spring. The limit switches 16 and 18 are the high pressure detection switch 16,
The limit switches 17 and 19 constitute zero pressure detection switches 17 and 19. 20, 21
are flow control valves disposed in the passage pipes 6 and 7, and 22 and 23 are check valves.

The limit switches 16, 17, 18, 19 are placed in a place where there is no danger that the cords connected to them will be disconnected.
, 19 are connected to an electrical control section (not shown) of the machine tool. Next, the operation of this embodiment will be explained.

When the pump 5 is driven and the control section operates the flap valve 4 to connect the pump 5 side and the passage pipe 6, the pump 5 side source pressure Po, the passage pipe 6 internal pressure P2, and the passage pipe 7 internal pressure P , the relationship is P2≠Po>P,>0.

At this time, the piston rod 12 moves in the projecting direction (
upper limit position), and the operating piece 14 closes the high pressure detection switch 1.
6, and turn on the switch 16 (O
N) Let it happen. At this time, the zero detection switch 17 is turned off. On the other hand, the piston rod 13 of the single-acting cylinder 11 moves against the elasticity of the coil spring due to the pressure P, and stops with the operation piece 15 located between the switch pieces of the limit switches 18 and 19. That is, switch 18,
19 are both turned off. In the tilted state, the piston rod 3 of the cylinder 1 is moved in the direction N by hydraulic pressure, and the table 2 is thereby moved. table 2
collides with the stopper 24 and is stopped by this stopper 24, the oil pressure of the passage pipes 6 and 7 becomes (P2=P
o)>P,=0, and the hydraulic pressure applied to the piston of the single-acting cylinder 11 becomes zero, so the piston rod 13 moves inward of the cylinder 11 (lower limit return position) by the coil spring, and the operating piece 15 moves to zero. . Detection switch 1
The switch 19 is turned on by making elastic contact with the switch piece 9. By turning on both the zero detection switch 19 and the high pressure detection switch 16, the control unit detects that the movable table has stopped at the stop position, and in response to this detection, the control unit sends a signal to the cut-off valve 4. The driving operation of cylinder 1 is stopped. When the switching valve 4 switches and the source oil pressure Po is supplied to the passage pipe 7, the piston rod 3 of the cylinder 1 moves in the arrow direction N.
The moving table 2 is moved in the opposite direction, thereby driving the moving table 2. When the movable table 2 collides with the stopper 25, the control section detects this by multiple checking (double closed state) with the high pressure detection switch 18 and the zero detection switch 17. Although the piston rods 12 and 13 of single-acting cylinders are used as the above-mentioned hydraulic pressure detecting moving body, it is also possible to use a device that can convert changes in fluid pressure into moving motion, such as a pluton tube or a bellows tube, as the hydraulic pressure detecting moving body. I can do it. In addition, when the table 2 is moved N' in the arrow direction, when the pump 5 side and the passage pipe 6 are connected, an impactful high pressure (surge pressure) is generated in the passage pipe 6, and this surge pressure causes the high pressure switch to close. 16 is turned on, this surge pressure causes the piston rod 13 to move to the right in the drawing, and the zero detection switch 19 is turned off, so no stop signal for the table 2 is sent to the electrical control section.

The same holds true when moving the table 2 in the direction opposite to the direction N. Also, ze. It is desirable that the detection switches 17 and 19 be turned on only when the oil pressure in the cylinders 10 and 11 becomes exactly zero, but there is no particular requirement for precision; It may be configured so that it is inserted. Since the present invention is configured as described above, even if a surge pressure occurs in the fluid circuit and the pressure in the circuit increases momentarily, the stoppage of the movable table will not be mistakenly detected due to this, and the movable table will not stop. Stoppage can be detected accurately and reliably, and since the detection switch can be placed at a position away from the moving body of the machine tool, there are effects such as being able to prevent cord breakage accidents.

[Brief explanation of the drawing]

The figure is an explanatory diagram showing a preferred embodiment of the present invention. i...Hydraulic cylinder, 2...Moving table,
3... Piston rod, 4... Switching valve, 5... Hydraulic pump, 6, 7... Fluid passage pipe, 8, 9... Branch Tube, 10, 11...
Single acting cylinder, 12, 13...Rod (hydraulic detection moving body), 14, 15...Switch operation piece, 16, 17, 18, 19...Limit switch, 20, 21...flow control valve, 22,
23...Check valve, 24,25...Stock/Gu-
.

Claims (1)

[Claims] 1. The first oil pressure detection moving body 14 that is moved by the hydraulic pressure of one side of the hydraulic cylinder 1 for driving the moving table of the machine tool and is pushed in the return direction, and the movement of the oil pressure detection moving body 14. A high pressure detection switch 16 whose closing position is set at a predetermined position in the upper limit direction of the range, a zero pressure detection switch 17 whose closing position is set at a predetermined position in the lower limit return direction of the movement range of the oil pressure detection moving body 12, The second oil pressure detection moving body 15 is moved by the other oil pressure of the cylinder 1 and is pushed in the return direction, and the closing position is set at a predetermined position in the upper limit direction of the movement range of the second oil pressure detection moving body 15. a high pressure detection switch 18, and a zero pressure detection switch 19 whose closed position is set to a predetermined position in the lower limit return direction of the second oil pressure detection moving body 13, A double closing signal when both the detection switch 16 and the zero pressure detection switch 19 on the side of the second oil pressure detection moving body 15 are turned on is used as the stop detection signal of the movable base, and the second oil pressure detection moving body 15 side high pressure detection switch 18 and the first oil pressure detection moving body 14
A device for detecting a stop position of a movable table in a machine tool, characterized in that a double closing signal when a zero pressure detection switch 17 on the side is both turned on is used as a stop detection signal for the movable table.