JPS5914305B2 - Ram displacement detection device in die-casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 15 The present invention relates to a ram displacement detection device in a die-casting machine.

To automatically control a die-casting machine, it is necessary to detect the amount of displacement of the ram, which is a movable part.

The position change can be made by setting a certain reference point.
Not only can it be matched, but it can also be converted into a velocity signal by first differentiation with respect to time, and into an acceleration signal by second order differentiation, so it has a wide range of applications and is an important detection quantity. . However, it is not easy to detect the position of the ram because the area around the die-casting machine is generally high temperature and there are many guests, the ram moves at a fairly high speed, and the machine is handled roughly. Conventionally, in order to detect such a displacement amount, a large number of grooves are provided on the surface of a magnetic bar that moves following the ram so as to repeat unevenness in the direction of movement 30, and on the other hand, the movement of the uneven portion is 35. A method in which a magnetic sensor including a magnet for magnetic detection is placed close to and facing the uneven portion, and detects changes in magnetic flux due to differences in magnetic resistance when the magnetic sensor faces the convex portion and when the magnetic sensor faces the concave portion 35 A detection device of the following type is known.

As magnetic sensors, those using magnetoresistive elements, Hall elements, etc. are known. In this type of detection device, in order to obtain good detection sensitivity or detection results, the gap between the magnetic sensor and the convex portion must be 0.5.
They must be placed in a positional relationship that does not stick to each other so that they are about mm apart, but this requires extremely high precision and complicated work, which not only increases costs, but also destroys the magnetic sensor if the two come into contact. There is a risk that you may be

Furthermore, if the groove is clogged with dust containing powder of a magnetic material, this is equivalent to the magnetic recess becoming shallower, and the detection sensitivity decreases. SUMMARY OF THE INVENTION An object of the present invention is to provide a ram displacement detection device for a die-casting machine that eliminates the drawbacks of conventional devices and maintains high sensitivity and stable accuracy. To achieve this objective, the present invention provides a tube made of a non-magnetic material with a smooth surface that can move following the ram through an arm attached to the ram of a die-casting machine, and a tube made of a non-magnetic material with a smooth surface that can move in the direction of movement. A row of magnets arranged so as to produce strength or weakness or different polarity at a constant pitch along the . fixedly arranged to slidably contact the outer surface of the tube,
a magnetic detection head that outputs an electric signal in response to the magnetism of the magnet array according to the movement of the tube, and the magnetic detection head has a dust seal part that closely seals the sensor chamber from dust on the outer surface of the tube. and a magnetic sensor is disposed in the sensor chamber at a distance from the outer surface of the tube.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows the overall configuration of the apparatus of the present invention.

A piston rod 3 connected to a piston 2 of a cylinder 1 drives a plunger tip 5 of a die-casting machine 4. The piston 2 and the piston rod 3 are actuated in the casting direction by introducing pressure medium from one port of the cylinder 1 via the conduit 6 and in the opposite direction by introducing pressure medium from the other port via the conduit 7. activated. Various types of cylinders are known,
It is also possible to use other devices than those shown in the drawings. piston rod 3
An arm 8 is fixed to. According to the invention, a smooth-surfaced tube 9 made of a non-magnetic material is fixed to the arm 8 so as to extend in a direction parallel to the piston rod 3. A fixed magnetic detection head 10 is slidably fitted into the tube 9. The electrical output of the magnetic detection head 10 is converted via a waveform processing circuit 11 into a signal having a waveform and absolute value suitable for various uses. On the inner surface of the tube 9, as shown in FIGS. 2 and 3, a magnet array 12 is arranged along the axial direction.

The magnetic sensing head 10 includes a body 13 that is slidably fitted into the tube 9.

A hole running in the radial direction is formed in the body 13 as a sensor chamber 14, and a magnetic sensor 15 is disposed within this sensor chamber 14. The magnetic sensor 15 is placed between the cover 16 that closes the sensor chamber 14 and the outer surface of the tube 9 by, for example, 0.5Tt7! It is held in a suspended form so that a gap of approximately L is formed. body 1
Dust seal rings 17 and 18 are attached to the magnetic sensor 15 and the pipe 9 to seal the space between the magnetic sensor 15 and the pipe 9 so that there is no dust harmful to magnetic detection between the pipe 9 and the magnetic sensor 15 .
The magnetic sensor 15 may be of any type as long as it is sensitive to magnetism and produces an electrical output, and may be, for example, a magnetoresistive element or a Hall element. The magnet tube 2 may be of a type in which the magnetic force changes at a constant pitch in the axial direction of the tube 9, and some embodiments thereof are shown in FIGS. 4 to 7.

The magnet array shown in FIG. 4 consists of a multipolar magnet 20 made by magnetizing a single rubber tape so that a large number of north and south poles are alternately located at a constant pitch in the longitudinal direction.

The magnet row in FIG.
The poles and south poles are arranged alternately.

The magnet array shown in FIG. 6 has a large number of unipolar magnets 22 magnetized in the radial direction of the tube 9 and arranged in the axial direction of the tube 9 with alternating north and south poles.

The magnet array of FIG. 7 corresponds to that of FIG. 6 with every other unipolar magnet removed.

In this case, the removed portion may be left blank, or a nonmagnetic or magnetic material may be placed thereon. The thickness of the magnet array 12 described above is about 1 to 2 mm at most, and the arrangement pitch of the magnetic poles or magnets can be about 5 m1, for example, although it depends on the required detection accuracy.

In FIGS. 2 and 3, the magnet array 12 is placed on the inner surface of the tube 9.
An example is shown in which the adhesive is attached only to a portion in the circumferential direction. On the other hand, FIGS. 8 and 9 show an embodiment in which the magnet array 24 is attached over the entire inner circumference of the tube 9. In this case, the arrangement of the magnets or magnetic poles may be as appropriate as shown in FIGS. 4 to 7. 10 and 11 show tube 9
This example is particularly suitable for cases where it is difficult to attach a magnet array to the inner surface of a magnet.

In FIG. 10, first, a spiral groove 27 with a pitch corresponding to the magnetic pole arrangement pitch is formed on the outer periphery of a rod 26 made of a non-magnetic material and has a size that can be inserted into the tube 9, and a tape is placed inside the spiral groove 27. A shaped magnet 28 is inserted into the tube 9. In FIG. 11, a large number of grooves 29 running in the circumferential direction perpendicular to the axis are formed on the outer periphery of the rod 26 at a pitch corresponding to the magnetic pole arrangement pitch, and a tape-shaped magnet 30 is embedded in each of the grooves 29. It is designed so that objects can be inserted into the tube 9. In this way, groove 27 or groove 2
By using the non-magnetic groove 26 having the groove 9 formed therein, the work of arranging the magnet becomes extremely easy. In the device of the present invention described above, the magnetic detection head 10 slides into contact with the non-magnetic tube 9 to magnetically detect the displacement amount of the magnet array, so that the magnetic gap can be reduced to a small value. Moreover, it can be kept stable, and high detection sensitivity can be obtained without making the magnetic gap that small.

Furthermore, by making the magnetic detection head a sliding contact type, dust that is harmful to detection does not accumulate between the magnetic sensor and the magnet array, and detection sensitivity does not decrease due to dust accumulation. . Furthermore, the device of the invention can measure well from low to high speeds (for example up to 40 m/s). Thus, according to the present invention, it is possible to detect the displacement of the ram while maintaining high sensitivity and stable accuracy even in a harsh atmosphere where there is high temperature, a lot of dust, and where the machine is handled roughly. Here, it is possible to provide a displacement amount detection device that is easy to maintain, has a long life, is highly reliable, and is versatile.

[Brief explanation of the drawing]

Fig. 1 is a layout diagram showing the overall configuration of the device of the present invention, Fig. 2 is a vertical cross-sectional view of the main parts of the device in Fig. 1, Fig. 3 is a cross-sectional view taken along the line in Fig. 2, and Fig. 4 , Fig. 5, Fig. 6, and Fig. 7 are explanatory diagrams showing different configuration examples of magnet rows, and Fig. 8 and Fig. 9 are longitudinal sections of an embodiment in which magnet rows are arranged all around the inner circumference of the tube. The drawings and end views, FIGS. 10 and 11 are side views showing different embodiments in which the magnet array is embedded in a groove formed in a rod. 1...Cylinder, 3...Piston rod, 4...Die casting machine, 5...Plunger chip, 9...Pipe, 10... ...Magnetic output head, 12, 24... Magnet row, 13...
...Body 1, 14...Sensor chamber, 15
...Magnetic sensor 17,18...Dust sensor.

Claims (1)

[Scope of Claims] 1. A tube made of a non-magnetic material with a smooth surface that can move following the ram via an arm attached to the ram of a die-casting machine, and a tube made of a non-magnetic material with a smooth surface along the moving direction. A magnet array arranged so as to produce strength or weakness or different polarity at a pitch,
a front air detection head that is fixedly arranged so as to be in slidable contact with the outer surface of the tube and outputs an electric signal in response to the magnetism of the magnet array according to the movement of the tube, the magnetic detection head The die-casting machine is characterized in that it has a dust seal part that seals the sensor chamber from dust in close contact with the outer surface of the tube, and a magnetic sensor is disposed in the sensor chamber slightly apart from the outer surface of the tube. ram displacement detection device. 2 The magnet array is constructed by embedding magnetic tapes magnetized to have different polarities in the thickness direction in grooves formed at a constant pitch on the outer periphery of a non-magnetic rod. The displacement amount detection device according to claim 1, characterized in that: 3. The displacement detection device according to claim 1, wherein the magnet array is made up of multi-pole magnets that are alternately magnetized at a constant pitch in the direction of movement of the tube. 4. The magnet row is characterized in that a large number of unipolar magnets magnetized with different polarities in the direction of movement of the tube are arranged so that NS and N alternate magnetic poles are located in the direction of movement of the tube. A displacement detection device according to claim 1.