JP3474449B2 - Rotation detection device of injection molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detecting device for an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold device.
After cooling and solidifying in the cavity space, the mold device is opened and the molded product is taken out.

The injection molding machine includes a mold clamping device and an injection device. The mold clamping device includes a fixed platen and a movable platen, and a mold clamping cylinder advances and retracts the movable platen to bring the mold device into and out of contact with the mold device. It is designed to let you. On the other hand, the injection device includes a heating cylinder that heats and melts the resin supplied from the hopper, and an injection nozzle that injects the melted resin, and a screw is rotatably and forwards and backwards in the heating cylinder. Arranged freely.
Then, the screw is moved forward to inject the resin from the injection nozzle, and the screw is moved backward to measure the resin.

By the way, in an electric injection molding machine, an injection motor and a metering motor are provided, and the rotational motion generated by driving the injection motor is converted into a linear motion to drive the screw. To move forward,
By driving a metering motor, the screw is rotated and retracted. Then, in order to detect the position of the screw in the heating cylinder, a sensor for detecting the rotation of an encoder or the like is attached to the shaft end of a rod-shaped rotor shaft to which the rotors of the injection motor and the measurement motor are fixed, The rotations of the injection motor and the metering motor are detected by the sensor.

[0005]

However, in the conventional injection molding machine, when an attempt is made to dispose a spline shaft for advancing and retracting the screw, a bearing box, a ball screw, etc. inside the rotor, the injection molding is performed. It becomes necessary to configure the motor for measuring or the motor for measuring by a hollow motor. In that case, since the rotor is fixed to the cylindrical rotor shaft, it becomes difficult to mount the sensor on the same axis as the rotor shaft.

Therefore, the rotations of the injection motor and the metering motor cannot be detected. An object of the present invention is to solve the problems of the conventional injection molding machine and to provide a rotation detection device for an injection molding machine capable of detecting the rotation of a hollow motor.

[0007]

Therefore, in the rotation detecting device of the injection molding machine of the present invention, a drive unit case,
A stator fixed to the drive unit case, a rotor disposed radially inward of the stator, and a hollow shaft rotatably disposed with respect to the drive unit case and having the rotor attached thereto. The measuring motor and the hollow shaft are spline-connected to the hollow shaft, and are arranged so as to move forward and backward, and are separated from the drive shaft connected to the screw and outside the outer diameters of the screw and the drive shaft. At a position, a sensor is provided which is attached to the front cover of the drive unit case while avoiding interference with the screw and the drive shaft, and which detects rotation of the hollow shaft.

In another rotation detecting device for an injection molding machine of the present invention, a drive unit case, a stator fixed to the drive unit case, a rotor arranged radially inward of the stator, and the drive unit. A metering motor, which is rotatably arranged with respect to the case, has a hollow shaft to which the rotor is attached, and is spline-connected to the hollow shaft in the hollow shaft, and is arranged to be movable back and forth, The drive shaft, which is connected to the screw, is located outside the outer diameters of the screw and the drive shaft, and is attached to the front cover of the drive unit case while avoiding interference with the screw and the drive shaft. A ring-shaped rotation which is arranged between the sensor for detecting rotation of the hollow shaft and the hollow shaft and the sensor, and through which the drive shaft is passed. And a dynamic means. The sensor detects the rotation of the hollow shaft via the rotation transmission means. In the rotation detection device of still another injection molding machine of the present invention, the sensor further detects rotation of the hollow shaft in a non-contact manner.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part of a drive unit according to the first embodiment of the present invention, and FIG. 2 shows an injection device according to the first embodiment of the present invention.
FIG. 3 is a second cross-sectional view showing the injection device according to the first embodiment of the present invention.

In FIG. 2, reference numeral 12 is a heating cylinder, and the heating cylinder 12 has an injection nozzle 12a at the front end (the left end in the drawing). Inside the heating cylinder 12, a screw 22 as an injection member is rotatably and movably arranged. And the screw 22
Has a screw head 22a at the front end, extends rearward (rightward in the drawing) in the heating cylinder 12, and is connected to a drive unit described later at the rear end (right end in the drawing). Around the screw 22, a screw
A spiral flight 23 is formed, and a groove 26 is formed by the flight 23.

Then, in a set position in the heating cylinder 12, that is, in a state where the screw 22 is placed at the most forward position (left side in the drawing) in the heating cylinder 12, the rear end portion of the groove 26 (see the drawing). A resin supply port 29 is formed at a position corresponding to the right end portion of
A hopper 30 is fixed to the resin supply port 29. Therefore, when the driving unit is driven and the screw 22 is retracted while being rotated during the weighing process, the pellet-shaped resin 33 in the hopper 30 drops and the heating cylinder 12 is rotated.
Enter the inside and move forward in the groove 26 (move to the left in the figure)
To be made.

A heater (not shown) is arranged around the heating cylinder 12 so that the heating cylinder 12 can be heated by the heater to melt the resin 33 in the groove 26. Therefore, when the screw 22 is moved backward by a predetermined amount (moved to the right in the figure) while rotating, the screw head 22a
One shot of the melted resin 33 is stored in front of.

Next, during the injection step, when the driving unit is driven to move the screw 22 forward without rotating, the resin 33 stored in front of the screw head 22a is injected from the injection nozzle 12a, The cavity space of a mold device (not shown) is filled. Next, the drive unit will be described.

In FIG. 3, 11 is a drive unit case surrounding the drive unit, and the drive unit case 11 is fixed to the rear end of the heating cylinder 12 (FIG. 2). The drive unit case 1
The reference numeral 1 includes a front cover 13, a center frame 15, a rear cover 17, a front frame 41 connecting the front cover 13 and the center frame 15, and a rear frame 42 connecting the center frame 15 and the rear cover 17. The front cover 13 and the front frame 41 are bolts b1, the front frame 41 and the center frame 15 are bolts b2, the center frame 15 and the rear frame 42 are bolts b3, and the rear frame 42 and the rear cover 17 are the same.
And are fixed by bolts b4.

Further, a metering motor 4 as a hollow motor is provided at the front part (left part in the figure) of the drive case 11.
4, the injection motors 45, which are hollow motors, are arranged in the rear part (right part in the drawing) on the same axis and on the same axis as the screw 22. The metering motor 44 includes a stator 46 fixed to the front frame 41 and an annular rotor 47 arranged radially inward of the stator 46, and the injection motor 45 is fixed to the rear frame 42. And a ring-shaped rotor 49 disposed radially inward of the stator 48.
Consists of.

The rotor 47 is rotatably supported by the drive unit case 11. Therefore, the rotor 47 has a cylindrical first rotor shaft 56 as a hollow shaft.
Is fitted and fixed, and the front end of the first rotor shaft 56 is supported by the front cover 13 by the bearing 51, and the rear end thereof is supported by the center frame 15 by the bearing 52.

On the other hand, the rotor 49 is also the drive unit case 11
It is rotatably supported with respect to. Therefore, the rotor 4
A tubular second rotor shaft 57 as a hollow shaft is fitted into and fixed to 9 of the second rotor shaft 5.
The front end of 7 is mounted on the center frame 15 by the bearing 53.
The rear ends of the rear frame 42 are supported by the bearings 54.

By the way, in the metering motor 44, by supplying a current of a predetermined frequency to the stator 46, the screw 22 can be retracted while rotating. Therefore, the sleeve 18 is arranged on the inner periphery of the front portion of the first rotor shaft 56, and the front end of the sleeve 18 and the front end of the first rotor shaft 56 are fixed by the bolt b5. Further, a first spline nut 62 is fixed to the rear end of the sleeve 18 by a bolt b12, and the first spline nut 6 is
2 and the first spline shaft 63 are spline-connected, and the screw 22 is fixed to the front end of the first spline shaft 63. In this case, the first spline nut 62 and the first spline shaft 63 constitute a first driving force transmission means, and the relative movement of the sleeve 18 and the first coupling 81, which will be described later, in the rotation direction is restricted.
Relative movement in the axial direction is allowed. The first spline shaft 63 has a length corresponding to the stroke of the screw 22.

Therefore, when the measuring motor 44 is driven to rotate the rotor 47, the rotation of the rotor 47 causes the first rotor shaft 56, the sleeve 18, the first spline nut 62 and the first spline shaft 63 to rotate. It is transmitted to the screw 22 via the screw 22 and rotates the screw 22. Then, the resin 33 advances in the groove 26 while being melted, and the screw 22 is moved backward by the back pressure generated as the resin 33 advances.

At this time, since the first spline nut 62 and the first spline shaft 63 are spline-connected, the first spline shaft 63 is retracted relative to the first spline nut 62. On the other hand, in the injection motor 45, by supplying a current of a predetermined frequency to the stator 48, the screw 22 can be moved forward without rotating. Therefore, an annular bearing retainer 64 is fixed to the rear end of the second rotor shaft 57, and the first shaft portion 65a of the ball screw shaft 65 is fitted and fixed to the inner periphery of the bearing retainer 64. The ball screw shaft 65 is rotatably supported by the drive unit case 11. That is, the ball screw shaft 65 is supported with respect to the rear cover 17 by the bearing 66 and the thrust bearing 68 via the bearing retainer 64. The first spline shaft 63 and the ball screw shaft 65 form a drive shaft.

A rear cap 77 is fixed to the rear cover 17 by a bolt b6 via an annular load meter 75, and the second shaft portion 65 of the ball screw shaft 65 is fixed.
b is supported by the bearing 67 with respect to the rear cap 77. The rear cap 77 has a bracket 8
An absolute value pulse encoder 85 is provided via 6.
The absolute value pulse encoder 85 includes the second shaft portion 65b.
The ball screw shaft 65 and the second rotor shaft 57 rotate, that is,
In addition to detecting the rotation of the injection motor 45, it functions as a screw position detecting means and detects the position of the screw 22 based on the rotation of the ball screw shaft 65.

A ball nut 69 is disposed in the second rotor shaft 57 so as to be able to move forward and backward, and the ball nut 69 and the ball screw shaft 65 are screwed together to form a movement direction converting means. Therefore, when the injection motor 45 is driven to rotate the rotor 49,
The rotation of the rotor 49 is transmitted to the ball screw shaft 65 via the second rotor shaft 57 and the bearing retainer 64, and the rotational movement is converted into the linear movement, and the ball nut 6
Move 9 back and forth. A stopper 19 is fixed to the front end of the ball screw shaft 65 by a bolt b13 so that the ball screw shaft 65 does not come off from the ball nut 69.

A second sleeve-shaped spline shaft 71 is fixed to the front end of the ball nut 69 by a bolt b11 so that the ball nut 69 does not rotate together with the ball screw shaft 65.
The second spline nut 76 fixed to 5 and the second spline shaft 71 are spline-connected. In this case, the second
The spline nut 76 and the second spline shaft 71 constitute a second driving force transmission means, and the center frame 1
5 and the relative movement of the bearing box 72 as the third driving force transmitting means described later in the rotation direction is restricted, and the relative movement in the axial direction is allowed. The second spline shaft 71 has a length corresponding to the stroke of the screw 22.

A bearing box 72 is fixed to the front end of the second spline shaft 71 by a bolt b7, and a thrust bearing 73 is arranged in the front of the bearing box 72 and a bearing 74 is arranged in the rear thereof.
In this case, the bearing box 72 restrains the relative movement in the axial direction of the first spline shaft 63 and the second spline shaft 71, and allows the relative movement in the rotation direction. Therefore, the first spline shaft 63 is supported by the thrust bearing 73 and the bearing 74 so as to be rotatable relative to the second spline shaft 71 and the ball nut 69.

The rear end shaft 22b of the screw 22 is fixed to the front end of the first spline shaft 63 via bolts b8 and b9 via a first coupling 81 and a second coupling 82. The first coupling 81 causes the sleeve 1 to move as the screw 22 advances and retracts.
It is possible to move the inside of 8. A recess 63a is formed at the rear end of the first spline shaft 63 so as not to interfere with the head of the bolt b13 at the retracted limit position of the first spline shaft 63. Therefore, the axial dimension of the injection device can be reduced.

Reference numeral 84 indicates a position off the screw 22 and the first spline shaft 63, that is, the screw 2
The screw 22 and the first spline shaft 6 are arranged at positions outside the outer diameters of the second and first spline shafts 63.
3 is an encoder arranged so as to avoid interference with the sleeve 18. The encoder 84 is connected to the sleeve 18 via a gear train 87 and functions as a second sensor. The rotation of the shaft, that is, the rotation of the metering motor 44 is detected. Further, 89 is a water cooling jacket, and the water cooling jacket 89 is fixed to the front cover 13 by bolts b10 and prevents heat from being transferred from the rear end of the heating cylinder 12 to the front cover 13.

Next, the operation of the drive unit having the above structure will be described. First, in the injection process, when a current is supplied to the stator 48 of the injection motor 45, the rotor 49 is rotated, and the rotation of the rotor 49 causes the second rotor shaft 5 to rotate.
7 through the bearing retainer 64 and the ball screw shaft 6
5, the ball screw shaft 65 is rotated.
At this time, since the second spline nut 76 fixed to the center frame 15 and the second spline shaft 71 are spline-connected, the ball nut 69 does not rotate. Therefore, thrust is generated in the ball nut 69, and the ball nut 69 is advanced.

During this time, the metering motor 44 is not driven and the rotor 47 is in a stopped state. Therefore, the first spline shaft 63 disposed in front of the ball nut 69.
Is advanced without rotating and the screw 2
Move 2 forward. In this way, the rotary motion generated by the injection motor 45 is converted into a linear motion by the ball screw shaft 65 and the ball nut 69. As a result, the resin 3 accumulated in front of the screw 22
3 can be ejected from the ejection nozzle 12a.

Next, in the weighing process, the weighing motor 4
When the electric current is supplied to the stator 46 of No. 4, the rotor 47 is rotated, and the rotation of the rotor 47 is rotated through the first rotor shaft 56, the sleeve 18, the first spline nut 62 and the first spline shaft 63. And the screw 22 is rotated. Along with this, the resin 33 advances in the groove 26 while being melted, and the screw 22 is retracted by the back pressure generated as the resin 33 advances.

At this time, since the first spline nut 62 and the first spline shaft 63 are spline-connected, the first spline shaft 63 is retracted relative to the first spline nut 62. Then, the injection motor 45 is driven while controlling the back pressure of the resin 33 to be measured, and the rotor 49 is rotated in the direction of retracting the screw 22. In this case, the load meter 75 detects a load applied to the screw 22 in the axial direction, and the back pressure can be calculated based on the load. In addition, a pressure sensor (not shown) is arranged in the heating cylinder 12, and the heating cylinder 1 is operated by the pressure sensor.
It is also possible to detect the pressure of the resin 33 in 2 and calculate the back pressure based on the pressure.

By the way, in the injection molding machine having the above construction, the screw 22 is provided inside the rotors 47 and 49.
Spline shaft 63, second spline shaft 71, bearing box 72, ball screw shaft 6 for advancing and retracting
5, a ball nut 69 and the like are arranged, and the injection motor 44 and the measuring motor 45 are hollow motors. Since the rotors 47 and 49 are fixed to the cylindrical first and second rotor shafts 56 and 57, respectively, it becomes difficult to directly attach the sensor to the first and second rotor shafts 56 and 57. I will end up.

Therefore, the sleeve 18 is fixed to the front end of the first rotor shaft 56 by the bolt b8, and the large diameter gear 91 (FIG. 1) as a rotation transmission means is fixed to the front end of the sleeve 18 by the bolt b21. . The large-diameter gear 91 is formed in an annular shape so that the first spline shaft 63, the first coupling 81, the second coupling 82, the rear end shaft 22b, and the like can pass inside.

Then, the encoder 84 is attached to the front cover 13, the encoder 84 and the small diameter gear 92 are connected, and the small diameter gear 92 and the large diameter gear 91 are meshed with each other. The encoder 84 detects the rotation of the second rotor shaft 56 via the large diameter gear 91 and the small diameter gear 92. The large-diameter gear 91 and the small-diameter gear 92 form a gear train 87.

Therefore, the rotation of the metering motor 44 can be detected without mounting a sensor on the same axis as the first rotor shaft 56. Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by giving the same code | symbol.

FIG. 4 is a cross-sectional view of the main parts of a drive unit according to the second embodiment of the present invention. In this case, the sleeve 18 is fixed to the front end (the left end in the drawing) of the first rotor shaft 56 as a hollow shaft by the bolt b8, and the rotor 95 having a plurality of teeth formed on the outer circumference is provided at the front end of the sleeve 18. It is fixed by the bolt b21. The inside of the rotor 95 is the first spline shaft 63, the first coupling 81, the second coupling 82, and the rear end shaft 22.
It is formed in an annular shape so that b and the like can pass through.

A non-contact type electromagnetic pickup 96 as a sensor is attached to the front cover 13, and the electromagnetic pickup 96 detects the rotation of the sleeve 18 by capturing the change of the magnetic flux accompanying the rotation of the rotor 95. Then, the rotation of the first rotor shaft 56 is detected. Therefore, the rotation of the measuring motor 44 can be detected without attaching a sensor to the first rotor shaft 56.

The electromagnetic pickup 96 is a rotor 95.
Since it is possible to detect the rotation of the measuring motor 44 without contact with, it is possible to prevent noise from being generated due to the detection of the rotation. In this embodiment, the electromagnetic pickup 96 is used as the non-contact type sensor, but a resolver may be used instead of the electromagnetic pickup 96. In this case, the sleeve 1
A rotor is attached to the front end of 8, and a stator is attached to the front cover 13 radially outward of the rotor.

In each of the above-described embodiments, an example in which the rotation of the metering motor 44 is detected has been described, but the rotation of the injection motor 45 can also be detected.
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0039]

As described above in detail, according to the present invention, in the rotation detecting device of the injection molding machine, the drive unit case, the stator fixed to the drive unit case, and the radial direction inside the stator. And a rotor disposed on one side, and a metering motor that is rotatably disposed with respect to the drive unit case and includes a hollow shaft to which the rotor is attached, and a hollow shaft and a spline connection in the hollow shaft. The drive shaft connected to the screw is disposed at a position distant from the outer diameters of the screw and the drive shaft while avoiding interference with the screw and the drive shaft, and the drive shaft And a sensor that is arranged to be attached to the front cover of the partial case and that detects the rotation of the hollow shaft.

In this case, the rotation of the hollow motor can be detected without mounting a sensor on the same axis as the hollow shaft.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a drive unit according to a first embodiment of the present invention.

FIG. 2 is a first cross-sectional view showing the injection device according to the first embodiment of the present invention.

FIG. 3 is a second cross-sectional view showing the injection device according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a drive unit according to a second embodiment of the present invention.

[Explanation of symbols] 11 Drive case 44 Metering motor 45 injection motor 46, 48 Stator 47,49 rotor 51-54 Bearing 56 First rotor shaft 57 Second rotor shaft 63 1st spline shaft 65 ball screw shaft 84 encoder 85 Absolute pulse encoder 91 large diameter gear 96 Electromagnetic pickup

Claims (3)

(57) [Claims] And 1. A (a) drive unit casing, rotated with respect to (b) stay data fixed to the drive unit casing, a rotor disposed radially inward from the stator, and the driving portion case is freely disposed, the metering motor having a hollow shaft in which the rotor is mounted, (c) Oite within the hollow shaft, the hollow shaft and scan
Is spline connected, are movably disposed Rutotomoni, scan
A drive shaft coupled to the clew, the position apart outwardly from the outer diameter of the; (d) screw and the drive shaft, to avoid interference with the screw and the drive shaft, prior to
A rotation detection device for an injection molding machine, comprising: a sensor that is mounted on the front cover of the drive unit case and that detects rotation of the hollow shaft. 2. A (a) drive unit casing, rotated with respect to (b) stay data fixed to the drive unit casing, a rotor disposed radially inward from the stator, and the driving portion case is freely disposed, the metering motor having a hollow shaft in which the rotor is mounted, (c) Oite within the hollow shaft, the hollow shaft and scan
Is spline connected, are movably disposed Rutotomoni, scan
A drive shaft coupled to the clew, the position apart outwardly from the outer diameter of the; (d) screw and the drive shaft, to avoid interference with the screw and the drive shaft, prior to
A sensor mounted on the front cover of the drive unit case for detecting rotation of the hollow shaft; and (e) disposed between the hollow shaft and the sensor for allowing the drive shaft to pass therethrough. which has a rotation transmission means annular be, the hollow Sha through (f) said sensor rotation transmission means
Rotation detecting device for an injection molding machine and detects the rotation of the shift. 3. The rotation detecting device for an injection molding machine according to claim 1, wherein the sensor detects rotation of the hollow shaft in a non-contact manner.