JPS61277410A - Pressure compensator of reciprocating motion equipment in thrust direction - Google Patents

Abstract

PURPOSE:To control wear and heat generation, by a method wherein pressure of the titled compensator is offset by applying pressure in the reverse direction to thrust force acting upon an output shaft by double acting type hydraulic cylinder provided on the rear of the output shaft. CONSTITUTION:Hydraulic oil 76 at a preset value is being supplied always to pressure accumulators 66, 79 and respective cylinders 63, 64 of a hydraulic cylinder 55 through servo-relief valves 68, 82 by a hydraulic pump 71 by taking in torque of a motor 72. Therefore, the thrust of an output shaft 4a is shared also by a piston 56 of the hydraulic cylinder 55. As the force of the output shaft 4a in an axial direction at the time of receiprocating linear motion of the same hardly acts upon a part of a feed screw unit due to a matter that as for a pressure compensator 54, thrust forces also in any direction of an axial line direction of the output shaft 4 are received by an action of the hydraulic cylinder 55, heat generation at the feed screw unit can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a thrust direction reciprocating motion device for imparting rotational motion and reciprocating linear motion in the thrust direction to an output shaft, and in particular, the present invention relates to a thrust direction reciprocating motion device for imparting rotational motion and reciprocating linear motion in the thrust direction to an output shaft, and in particular, the thrust in the axial direction is compensated by a hydraulic system. It pertains to equipment for

In the prior art, for example, in a plastic crosstalk device, the thrust shaft is given not only rotational motion about the axis, but also reciprocating linear motion in the axial direction. In other words, this type of drive device includes a reciprocating drive system in addition to a rotary drive system.

Conventional reciprocating drive mechanisms consist of a mechanical crank mechanism that applies a reciprocating linear motion in the axial direction to the output shaft while receiving a large thrust, or a servo motor that operates a feed screw unit to connect the output shaft and the feed. Reciprocating linear motion is provided in the axial direction by rotational motion relative to the screw unit.

In the former crank mechanism, frictional force acts on the connecting parts of the mechanical elements and heat is generated, resulting in a large loss of power (and the effect of the generated heat on other mechanical elements cannot be ignored. With the latter type of feed screw unit, the surface pressure on the screw surface of the feed screw unit becomes excessive, which significantly shortens the life of the component, and the required power of the servo motor that drives it also increases, making it necessary to use a large motor. This is a technical or economic limit.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide a feed screw unit type reciprocating linear motion device in the thrust direction, in which the mechanism, particularly the portions other than the feed screw unit, can receive the enormous changing thrust generated in the output shaft. By stopping this, the load in the thrust direction applied to mechanical elements such as the feed screw unit can be reduced, and the driving force of the servo motor for driving the same can be reduced.

SUMMARY OF THE INVENTION Therefore, the present invention provides a double-acting hydraulic cylinder at the rear end portion of the output shaft, and uses the piston of this hydraulic cylinder to
A force in the opposite direction is applied to the thrust acting on the output shaft to cancel out the thrust.

Here, each cylinder chamber of the hydraulic cylinder is adjusted to an appropriate pressure value by a hydraulic pressure source that increases the pressure and a servo relief valve that decreases the pressure. Further, the internal pressure fluctuates pulsatingly due to the reciprocating linear motion of the output shaft, but such pressure fluctuations are absorbed by the pressure accumulator of the hydraulic system. Furthermore, the control section of the servo relief valve detects the internal pressure in the cylinder chamber of the hydraulic cylinder using a pressure sensor, etc., and at the same time detects the crank movement or the driving force of the feed screw unit, so that the relationship between them is always the desired one. By controlling the on/off operation of the servo relief valve, the pressure in the hydraulic system is always automatically adjusted to the optimum pressure value.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an embodiment of the present invention will be specifically described below with reference to the drawings.

First, FIG. 1 shows a thrust direction reciprocating bag Wt1, which is the premise of the present invention, together with a kneading extruder 2 to be driven. This thrust direction reciprocating device 1 includes an output shaft 4 inside a gear case 3, and an output shaft 4 outside the gear case 3.
A main motor 5 is provided to provide rotation to the main motor 5, and a servo motor 6 is provided to provide reciprocating linear motion in the thrust direction, that is, the axial direction, to the output shaft 4.

The output shaft 4 is rotatably supported by a front bearing 7 and slidably in the thrust direction, that is, in the axial direction, and is fitted into a spline sleeve 10 with a spline 9 formed in a part. A part of the female thread 11 which is mated and fixed to another part is connected to the male thread 8 of the feed nut 12 under a threaded pair.

The spline sleeve 10 is for transmitting only rotational motion to the output shaft 4, and is rotatably supported with respect to the gear case 3 by ball bearings 13 at the front and rear ends, and supports the output gear 14 at the intermediate portion. It is held in a non-rotating state. The feed nut 12 is for giving linear reciprocating motion in the thrust direction to the output shaft 4, and is fixed to the center of the output gear 15 in a non-rotating state and in a state capable of receiving and stopping the thrust. It is rotatably indirectly supported by the gear case 3 via the output gear 15 by front and rear ball bearings 16 .

On the other hand, the rotation of the main motor 5 is transmitted to the intermediate shaft 18 by, for example, a timing belt/pulley 17. The intermediate shaft 18 is rotatably supported in the gear case 3 by a ball bearing 19, and supports a gear 20 meshing with the output gear 14 and a bevel gear 21. This bevel gear 21 meshes with a bevel gear 22 fixed to a shaft 23. This shaft 23 is rotatably supported by the gear case 3, and has one end connected to the gear 24.
and is connected to an absolute type encoder 25 at the tip.

The servo motor 6 is attached to the outer surface of the gear case 3, and the rotation of the motor shaft 26 is controlled by the gear 2.
7. It is transmitted to the output gear 15 via the gears 29 and 30 of the intermediate shaft 28. Note that this intermediate shaft 28 is connected to the ball bearing 3
1 is supported by the gear case 3, and meshes with a bevel gear 33 of a differential gear mechanism 34 by a bevel gear 32 attached to an extended portion thereof. This differential gear mechanism 34 has a bevel gear 33 on one input side.
and the rotation difference between the gear 35 on the other input side that meshes with the gear 24 are transmitted as outputs to the encoder 39 for differential detection via the detection shaft 36 and gears 37 and 38.

By the way, the mixed wire extruder 2 to be driven includes a screw 40 to be driven inside a screw housing 41 in a state in which it is rotatable and slidable in the thrust direction. This screw 40 is connected to the output shaft 4 by a coupling 42. The screw housing 41 is provided with a heater 46 at the outer peripheral portion,
It also has a bottle 47 that can pass through the notch of the screw 40 inside, and is in contact with a nozzle 48 pushed by hydraulic pressure at the opening at the tip. The material 43 to be kneaded is stored inside a hopper 44 and fed into the base end portion of the screw 40 while being mixed by an agitator 45.

Next, FIG. 2 shows a control device 50 and a speed change control device 51. As shown in FIG. The servo motor 6 is controlled by a servo driver 52. Further, the main motor 5 is
It is controlled to rotate at a predetermined speed by a speed change control device 51 that is separate from the control device 50. The encoders 25 and 39 are each connected to a controller 53, which in turn is connected to a servo driver 52 of the servo motor 6 and a position command memory 49.

Now, as shown in FIG. 1, the pressure compensator 54 of the present invention has a double-acting hydraulic cylinder 55 at the rear end portion of the output shaft 4.
It is equipped with This hydraulic cylinder 55 is connected to the gear case 3
The piston 56 is fixed to the rear end surface, and the piston 56 is slidably fitted into the gear case 3 with an O-ring 58 interposed therebetween by a hollow piston rod 57 that is integral with the piston rod, and a thrust bearing is mounted inside the piston 56. 59, and is inserted concentrically into the extension portion 4a of the output shaft 4. Note that the rear end portion of this extension portion 4a is a piston 56.
A rotary joint 61 protrudes outward from a sleeve 60 fixed to the rotary joint 61 so that cooling oil 62 can be taken in cyclically.

Next, FIG. 3 shows the configuration of the pressure compensator 54 of the present invention. One cylinder chamber 63 of the hydraulic cylinder 55
is connected to a pressure accumulator 66 and a pressure sensor 67 through a conduit 65, and further branches to a servo relief valve 68, a reference pressure sensor 69, and a hydraulic pump 7 through a conduit 70.
Connected to the outlet side of 1. This hydraulic pump 71
is connected to a pump driving motor 72, and is immersed in driving oil 75 stored in an oil tank 74 by a strainer 73 on the suction side.

The other cylinder chamber 64 of the hydraulic cylinder 55 is
Similarly, a servo relief valve 7 for bypass is connected via a conduit 77.
8, is connected to a pressure accumulator 79 and a pressure sensor 80, and further branches to a servo relief valve 82 via a pipe line 81.
, and is connected to the discharge side of the hydraulic pump 71 via a relief valve 83. The return side portions of the servo relief valves 68, 78, 82 and the relief valve 83 are submerged in the driving oil 75 through a conduit 85. In addition, a pressure gauge 8 is installed on the discharge side of the hydraulic pump 71.
4 is attached.

These pressure sensors 67, 80 and reference pressure sensor 69 are connected to the servo driver 52 as shown in FIG.
The controller 86 is also connected to the servo relief valves 68 .
78 and 82, respectively. The controller 53 also includes a detection circuit 8 connected to a current detector 89.
7, and this detection circuit 87 and controller 86 are connected to each other. The detection circuit 89 described above detects the value of the current flowing between the servo motor 6 and the servo driver 52.

Note that the pump driving motor 7°2 is placed under the control of the main controller 88.

Operation of the Invention Next, the operation of the pressure compensator 54 of the present invention will be explained together with a series of operations of the thrust direction reciprocating device 1.

First, the speed change control device 51 rotates the main motor 5 at a predetermined speed. At this time, the rotation of the main motor 5 is controlled by the timing belt/pulley 17, the intermediate shaft 18, and the gear 2.
0 and the output gear 14, the spline sleeve 10
transmitted to. Therefore, this spline sleeve IO transmits only the rotational motion to the output shaft 4 while allowing the linear motion of the output shaft 4 in the thrust direction. In this way,
The output shaft 4 rotates the screw 40 of the mixed extruder 2 at a predetermined speed.

On the other hand, the controller 53 detects the rotation angle of the output shaft 4 using the encoder 25, and sequentially reads from the position command memory 49 the amount of displacement in the thrust direction to be applied to the output shaft 4 at the detected rotation angle. Such a displacement amount is input in advance as a sinusoidal curve for each rotation angle of the output shaft 4, for example.

During this time, the differential gear mechanism 34 controls the rotation of the main motor 5, that is, the rotation of the output shaft 4, and the rotation of the servo motor 6.
That is, the rotation of the feed nut 12 is taken in, the rotation difference between them is detected, and the rotation difference is transmitted to the encoder 39. As a result, the output signal of the encoder 39 corresponds to the relative rotational difference between the output shaft 4 and the feed nut 12.

Therefore, the controller 5 compares the target displacement amount of a certain rotation angle of the output shaft 4 with the rotation difference as the output of the encoder 25, and gives a rotation command to the servo driver 52 of the servo motor 6 based on the deviation. . As a result, the servo motor 6 rotates the feed nut 12 in order to give the output shaft 4 a target displacement amount in the thrust direction.

For example, if the feed nut 12 is rotating at the same rotation speed as the output shaft 4, there will be no relative displacement in the thrust direction between the female screw 11 and the feed nut 12, and the output shaft 4 will rotate at the same rotation speed as the output shaft 4. It will rotate without moving in the direction of the thrust. However, when the feed nut 12 rotates in the same direction at a higher rotational speed than the output shaft 4, the output shaft 4 moves backward together with the screw 40, that is, to the right in the drawing. Conversely, when the feed nut 12 rotates in the same rotation direction as the output shaft 4 but at a lower rotation speed, the output shaft 4 and the screw 40 move forward, that is, to the left in the drawing. Become.

In this way, the servo motor 6 periodically repeats acceleration and deceleration in the same direction as the output shaft 4 and around a certain rotational speed along a target displacement amount, for example, along a sine wave curve. While rotating, the output shaft 4 repeats reciprocating linear motion together with the screw 40 in the direction of its thrust due to the screw action of the female screw 11 and the feed nut 12 at the same time. Moreover, the stroke and relative position of this reciprocating linear motion can be freely set by changing the data to be input to the controller 53.

In this way, the screw knee 40 feeds the material 43 one after another by screwing it, mixes the material 43 in a molten state, and sends the material 43 through the nozzle 4.
Push forward from part 8. During this time, pin 47
By preventing the material 43 from progressing in the feeding direction, the material 4
A shearing force is applied to 3 to facilitate cross-wire work. As already mentioned, since the screw 40 has a notch in the screwed part, when the screw 40 is driven by the output shaft 4 and makes a reciprocating linear movement in the thrust direction, the pin 47
The threaded notch of the screw 40 also passes through the cutout portion, allowing mechanical rotation and reciprocating motion. The material 43 after kneading is intermittently discharged to the outside by pushing open the nozzle 48.

On the other hand, the hydraulic pump 71 always takes in the rotational force of the motor 72 and supplies the pressure oil 76 at a predetermined pressure value to each cylinder of the pressure accumulator, 66.79, and the hydraulic cylinder 55 via the servo relief valve 68.82. It supplies chambers 63 and 64. Therefore, the thrust of the output shaft 4 is generated by the hydraulic cylinder 55.
This will also be shared by the piston 56 of. Therefore, the pressure of the pressure oil 76 must be set to a pressure value that can sufficiently withstand the thrust of the output shaft 4 in the backward direction, that is, the reaction force thereof.

Therefore, the controller 86 inputs the pressure signal from the pressure sensor 67.80 and calculates the internal pressure value of the pressure accumulator 66.79, that is, the cylinder chamber 63.64 of the hydraulic cylinder 55.
Detect the pressure values individually, and based on the detection results,
Controls the on/off state of the servo relief valves 68, 78, and 82. When the internal pressure of the cylinder chamber 63.64 rises above a predetermined pressure value, the servo relief valve 68.78.8
2 performs on/off operation separately, and the pressure oil 7
6 is returned to the oil tank 74 via a pipe 85.

Note that during this operation, the detection circuit 87 detects that the servo motor 6
The servo relief valve 68, 78, 820
It takes the timing of on/off operation. When the internal pressure of the cylinder chamber 63 suddenly increases, the pressure oil 76 in the cylinder chamber 64 is directly discharged to the outside from the servo relief valve 78 without passing through the servo relief valve 82. The piston 5G is capable of moving leftward in FIG. 3 at a high speed. As a result, the thrust of the output shaft 4 can be quickly shared by the hydraulic cylinder 55. As already mentioned, this hydraulic cylinder 55 is of a double-acting type, and the pressure values of each cylinder chamber 63 and 64 are individually controlled, so that the output shaft 4
is subjected to hydraulic pressure sufficient to counteract the thrust of the output shaft 4 in either direction. Note that when the oil pressure on the discharge side of the hydraulic pump 71 is low, the reference pressure sensor
69 detects the state and connects the servo relief valve 68.78
．． In order to prohibit turning on (opening operation) 82, a signal continues to be sent to controller 86.

By the way, when the output shaft 4 reciprocates in the axial direction, its thrust also changes in a pulsating manner. Therefore, the pressure value of the pressure oil 76 changes in a pulsating manner under the control of the controller 86 in synchronization with the pulsating change in its thrust. Such pulsating changes in pressure values are absorbed to some extent by the function of the pressure accumulators 66,79.

However, if there is a control delay in this hydraulic system and it resonates with the reciprocating motion of the output shaft 4, the hunting phenomenon is likely to occur in the hydraulic system. Such a hunting phenomenon in the hydraulic system can be prevented by operating the servo relief valve 78 only in the area where the maximum thrust of the output shaft 4 is generated, or by setting the pressure value of the cylinder chamber 63, 64 to prevent vibrational movement of the output shaft 4. This can be prevented more reliably by preventing it.

Although the pressure oil 76 inside the hydraulic cylinder 55 and pressure accumulator 66.79 is at a high temperature, it is discharged from the servo relief valve 68.78.82 and stored in an oil tank 74 provided outside the machine. In the process of being used again, the heat is dissipated to the outside so as not to have an adverse thermal effect on the parts of the thrust direction reciprocating device 1.

In this way, the pressure compensator 54 stops receiving thrust in any direction in the axial direction of the output shaft 4 by the action of the hydraulic cylinder 55. Almost no force acts on the lead screw unit, i.e. the internal thread 14 and the lead nut 22 part. Therefore, the generation of heat in the feed screw unit is suppressed, and the servo motor 4 required to drive it is suppressed.
This means that only a small driving torque is required.

Effect of the invention The present invention provides the following effects.

First of all, the axial force generated on the output shaft is stopped by the hydraulic cylinder, which reduces the surface pressure on the threads of the feed screw unit and the load on those bearings, which reduces their wear and tear. In addition to minimizing heat generation,
The torque of the servo motor is small, so the overall device structure can be made compact and inexpensive.

Second, the controller measures the actual force on the output shaft and automatically adjusts the internal pressure of the hydraulic cylinder accordingly,
Since it follows the fluctuations in the thrust of the output shaft, a force proportional to the thrust is always obtained not only during steady operation but also at startup, so the rotational movement and reciprocating linear movement of the output shaft can be performed over a wide range of freedom. degree is obtained.

Thirdly, the hydraulic cylinder is configured as a double-acting cylinder, and a pressure control system is provided not only in one cylinder chamber but also in the other cylinder chamber, so the thrust force in either direction of the output shaft is It can also be adequately addressed.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the thrust direction reciprocating device, Fig. 2 is a block diagram of the control device, Fig. 3 is a piping diagram of the pressure compensator of the present invention, and Fig. 4 is a block diagram of the controller portion. be. 1. Thrust direction reciprocating device, 2. Kneading extruder,
4...Output shaft, 5...Main motor, 6...Servo motor, 11...Female thread, 12...Feed nut, 25.3
9... Encoder, 34... Differential gear mechanism, 50... Control device, 51... Speed change control device, 52... Servo driver, 53. 86... Controller, 54... Pressure compensator, 55... Double Dynamic hydraulic cylinder, 56... Piston, 63.64... Cylinder chamber, 66.79... Pressure accumulator, 67... Pressure sensor, 68.82... Servo relief valve, 69... Reference pressure sensor. , 71... Hydraulic pump, 78... Servo relief valve, 80... Pressure sensor. Figure 3 Figure 4

Claims (1)

[Claims] In a thrust direction reciprocating motion device that gives an output shaft a rotational motion about the axis and a reciprocating motion in the axial direction by a feed screw unit, the output shaft is connected to the rear end of the output shaft by a piston in a state that allows the rotational motion. A double-acting hydraulic cylinder, a hydraulic power source connected to each cylinder chamber of this hydraulic cylinder via a pressure accumulator via a pipeline, and the pressure of each hydraulic power source can be independently and arbitrarily automatically controlled by a signal. A pressure control circuit that can be set and changed, detects the driving force of the feed screw unit, and automatically calculates the thrust compensation pressure so that the value is always within a specified range.
1. A pressure compensation device for a reciprocating motion device in a thrust direction, comprising a control section that outputs a signal.