JPH04357307A - Pneumatic cylinder positioning device - Google Patents

Abstract

PURPOSE:To enable stable positioning by computing a volume inside a cylinder from a cylinder inner diameter, cylinder stroke and each measured value of pressure changes, varying a total effective sectional area of a plurality of solenoid valves according to the computed result, and thereby keeping pressure in the cylinder constant. CONSTITUTION:In a magnetic rodless pneumatic cylinder 1, magnets are assembled in a piston and a cylinder movable part outside the cylinder. The cylinder movable part that is, a slider 3 is moved together with the movement of the piston through the magnetic connection of both magnets. The piston is moved and controlled by opening/closing a supplying solenoid valve 31 and a plurality of exhausting solenoid valves 32(32a to 32d) parallelly connected to each other, arranged in a solenoid valve box 29. A volume inside the cylinder chamber is computed based on each measured value of pneumatic pressures and a cylinder inner diameter. A total effective sectional area is varied by controlling the exhausting solenoid valves 32 having effective sectional areas proportional to the cylinder volume. Pressure in the cylinder is thus kept constant.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning control system for a robot operated by a rodless pneumatic cylinder.

0002

[Prior Art] As a prior art related to the present invention, there is an air cylinder control method in which a drive unit used as a robot hand is operated by an air cylinder, but with this method, positioning accuracy deteriorates when fluctuations in frictional force become large. It is.

As an improved device for this, there is Japanese Patent Application No. 2-337830 filed by the present applicant. This device uses one solenoid valve installed on both sides of the cylinder to control displacement, speed, and
The acceleration is measured, the setting error of Crohn's friction is estimated from these values, and the differential pressure corresponding to the friction is corrected from this value.

However, in the above control method, since the effective cross-sectional area of the solenoid valve is constant, the flow rate is always constant, and when the piston moves from near the right end to the right, the volume on the exhaust side decreases, so the pressure changes. is large, causing an overrun phenomenon as shown in FIG. 4(a), which increases the positioning time.

Furthermore, when the piston moves from the left end to the right, the volume on the exhaust side is large, so the change in pressure is small;
), the positioning time becomes longer and the accuracy deteriorates.

[0006]

[Problem to be Solved by the Invention] The problem to be solved is that in the air cylinder control system, when the piston moves to the left or right, the operating speed and
The technical problem is to develop a device that further improves positioning performance such as positioning time.

[0007]

[Means for Solving the Problems] The present invention provides air pipes at both ends of a rodless pneumatic cylinder having a slider on which a position sensor is arranged, a pressure sensor and a solenoid valve on each of the pipes, and one pipe has a silencer, In a slider positioning device for a pneumatic cylinder device, the other piping is provided with an exhaust port, and a plurality of solenoid valves are arranged on the exhaust port side, and the slider When positioning the valve at a desired position, measure the cylinder inner diameter, stroke, and changes during operation, calculate the volume inside the cylinder chamber from these values, and calculate the total effective volume of the plurality of solenoid valves in proportion to the volume. A pneumatic cylinder positioning device that constantly maintains constant pressure fluctuations within the cylinder during slider positioning by changing the cross-sectional area.

[0008]

[Operation] Measure the cylinder inner diameter, stroke, and pressure change during operation, calculate the volume inside the cylinder from the measured values, and if the volume is large in proportion to the volume, calculate the total effective cross-sectional area of multiple solenoid valves. If the volume is small, the total effective area of the plurality of cylinders is made small to change the flow rate sent through the speed control, thereby keeping the pressure fluctuation inside the cylinder constant and stable positioning.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are explanatory diagrams of a positioning device incorporating a pneumatic cylinder, a control device, and a solenoid valve box.

1 is a pneumatic cylinder, 2 is a cylinder movable part, 3 is a slider, 4 is a guide rail, 5 is a guide bearing, 6 is a frame, 7 is a position sensor, 8 is a scale for position sensor, 9 is a branch pipe, 10 is a pressure sensor, 11 is a tube, 12 is a solenoid valve, 13 is an air supply port, 14 is an exhaust port,
15 is an air supply pipe, 16 is a control device, 17 is a CPU, 18
is an up-down counter, 19 is an A/D converter, 20 is a solenoid valve drive circuit, 21 is a memory, and 22 is an input/output circuit (I
/O), 23 is a silencer, 24 is a piston, 25 is a side plate, 26 is a pressure sensor signal line, 27 is a position sensor signal line, 28 is a solenoid valve driving power line, 29 is a solenoid valve box, 3
0 is a speed controller, 31 is a supply solenoid valve, 32
has a solenoid valve for exhaust.

Magnets are incorporated in the piston 24 inside the cylinder and the cylinder movable part 2 outside the cylinder of the magnetic rodless type pneumatic cylinder, and due to their magnetic coupling, the cylinder movable part 2 moves as the piston 24 moves.
is a moving structure.

Both ends of the cylinder 1 are supported by side plates 25 fixed to the frame 6.

A slider 3 is attached to the cylinder movable portion 2, and the slider 3 is supported by a guide bearing 5 that slides on a guide rail 4 attached to a frame 6.

A position sensor 7 is attached to the cylinder movable section 2 at a fixed distance apart from a position sensor scale 8 which is attached to the frame 6 parallel to the cylinder movable section 2.

A pressure sensor 10 is attached to both sides of the cylinder via a branch pipe 9, and the other side is connected to a solenoid valve box 29 via a tube 11. A supply pipe 13 is connected to the air supply port of the solenoid valve box 29. is connected and exhaust port 1
4 is connected to a silencer 23.

The control device 16 includes a pressure sensor signal line 26,
A position sensor signal line 27 and a solenoid valve drive power line 28 are connected.

Furthermore, as shown in FIG. 2, a solenoid valve box 2
9 is connected to a plurality of exhaust electromagnetic valves 32a, 32b... branched from the tube 11, and four exhaust electromagnetic valves 32a, 32b..., one each on the exhaust side. Speed controllers 30a, 30b, . . . are attached, and the effective cross-sectional area is in the ratio of 1:2:4:8.

A supply solenoid valve 31 is also installed on the supply side.

In the above configuration, the exhaust solenoid valves 32a, 3
2b..., the position of the slider 3 is determined by the position sensor 7, the position sensor signal line 27, and the up/down counter 1.
8, then calculate the volume inside the cylinder chamber, and select a solenoid valve with an effective cross-sectional area proportional to it using 4 bits 1.
Commands are given in 6 steps.

When the exhaust electromagnetic valves 32a, 32b, . . . are energized by the electromagnetic valve drive circuit 20 inside the control device, they enter an exhaust state and the pressure in the cylinder chamber decreases.

Further, when the exhaust solenoid valves 32a, 32b, . . . are de-energized and the supply solenoid valve 31 is energized, air is supplied, and the pressure in the cylinder chamber increases to reach the supply pressure.

The pressure inside the cylinder chamber is measured by a pressure sensor 10, a pressure signal line 26, and an A/D converter 19.

[0023] In this way, the total effective area of the solenoid valve is increased,
If the volume is small, the total effective area of the solenoid valve is reduced, specifically by closing one or two of the solenoid valves 32a, 32b, . . . .

By changing the effective cross-sectional area and making the flow rate variable in this way, pressure fluctuations within the cylinder can be kept constant and stable positioning can be achieved.

FIG. 3 shows stable pressure fluctuations in the cylinder according to this embodiment, and shows that there is no overrun phenomenon as in the conventional example, and the pressure becomes constant in a short time.

[0026]

[Effects] The present invention has the following effects. That is, (1)
Even in the case of long strokes, stable positioning time can be maintained at all times, whether in the middle of the cylinder or near the end points.

(2) By changing the effective cross-sectional area S, it is possible to set a speed suitable for high-speed operation or low-speed operation.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a positioning device and a control device incorporating a pneumatic cylinder.

FIG. 2 is a block diagram inside the solenoid valve box.

FIG. 3 is a pressure change diagram within the cylinder according to this embodiment.

[Figure 4] (a) is a pressure change diagram in the cylinder according to the conventional example.
(b) shows the case when the piston moves to the right, and (b) shows the case when the piston moves to the left.

[Explanation of symbols]

1 Pneumatic cylinder 3 Slider 7 Position sensor 10 Pressure sensor 12 Solenoid valve 14 Exhaust port 31 Solenoid valve for supply 32 Solenoid valve for exhaust

Claims (1)

[Claims] Claim 1: A rodless pneumatic cylinder having a slider on which a position sensor is arranged, air pipes provided at both ends,
A slider positioning device for a pneumatic cylinder device, comprising a pressure sensor and a solenoid valve in each of the pipes, a silencer in one pipe and an exhaust port in the other pipe, and a control device for controlling the pressure sensor, position sensor, and solenoid valve. When arranging multiple solenoid valves on the exhaust port side and positioning the slider at an arbitrary position, the cylinder inner diameter,
By measuring the stroke and displacement during operation, calculating the volume inside the cylinder chamber from these values, and changing the total effective cross-sectional area of the solenoid valve in proportion to the volume, the pressure inside the cylinder when positioning the slider can be adjusted. A pneumatic cylinder positioning device that keeps fluctuations constant.