JP3491008B2 - Injection equipment 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 an injection molding machine for injecting a molten resin in a heating cylinder into a molding cavity of a mold by advancing a screw by utilizing a screw mechanism for converting a rotary motion into a linear motion. Injection device.

[0002]

2. Description of the Related Art As an injection device of an injection molding machine for advancing a screw by utilizing a screw mechanism, one shown in FIG. 6 is known (Japanese Patent No. 2754356). Explaining this, a plurality of tie rods 54 provided by integrally connecting a heating cylinder holding member 52 having a heating cylinder 51 attached to the front surface and a fixed plate 53, and a screw 5 on the front surface.
A ball holding member 56 having a screw holding member 56 movably supported along a tie rod 54 and fixed to a fixing plate 53 via an annular load cell 57.
Further, the ball screw shaft 59 is screwed with its central axis aligned with the central axis of the screw 55 to rotatably support the front end of the ball screw shaft 59 on the bearing 60 of the screw holding member 56. The timing belt 64 is wound around the driven pulley 61 attached to the drive pulley 63 of the servo motor 62 fixed to the screw holding member 56, and the ball screw shaft 59 is rotated by the servo motor 62 so that the screw holding member 56 and the screw holding member 56 are rotated together. The screw 55 is advanced to the left in FIG. 6 so that the molten resin in the heating cylinder 51 is injected into the molding cavity of a mold (not shown).

Reference numeral 66 is an electric motor, which is the screw holding member 5.
6 is fixed to the pulley 67 and the timing belt 6
The screw 55 is rotated via 8 and the pulley 69.

[0004]

The injection device of the above injection molding machine has the following problems. (1) Since the bolt 65 that attaches the load cell 57 to the fixed plate 53 receives a high load at the time of injection, a large measurement error is likely to occur due to the deformation of the load cell 57 and the elongation of the bolt 65. (2) Since the rotational torque of the ball screw shaft 59 acts on the load cell 57 via the ball nut 58, the measurement accuracy is impaired. (3) The load cell 57 must be formed in an annular shape, which increases the cost.

An object of the present invention is to provide an injection device of an injection molding machine capable of detecting pressure with high accuracy. Another object of the present invention is to provide an injection device of an injection molding machine which does not require a pressure detector having a special shape such as an annular shape.

[0006]

In order to achieve at least one of the above objects, the invention according to claim 1 integrally connects a heating cylinder holding member having a heating cylinder attached to the front surface and a fixing plate. To multiple tie rods
A screw holding member having a screw on the front surface is movably supported along a tie rod, and a ball screw shaft is screwed to a ball nut fixed to the fixing plate with its central axis aligned with the central axis of the screw. An injection device of an injection molding machine in which a servomotor for rotating the ball screw shaft to move the screw holding member together with the screw along a tie rod is connected to the ball screw shaft, A pusher plate is attached via a pressure detector, and a front end portion of the ball screw shaft is rotatably supported by a bearing of the pusher plate.

In this means, when the ball screw shaft is rotated in the forward direction by the servo motor, the pusher plate presses the screw holding member via the pressure detector, and the screw holding member moves forward with the screw to move the molten resin. Inject. At this time, the pressure detector detects the injection pressure compressed between the pusher plate and the screw holding member. Since the ball screw shaft is rotatably supported by the bearing of the pusher plate, the rotational force of the ball screw shaft is hardly transmitted to the pressure detector.

In the injection device of the injection molding machine, it is preferable that the pusher plate is movably supported by the tie rod (claim 2). In this configuration, the tie rod
Completely prevent the pusher plate from rotating due to the rotation of the ball nut.

Further, the servomotor can be supported by an auxiliary member attached to the pusher plate (claim 3). In this case, the servomotor can be connected to the rear end of the ball screw shaft via a coupling (claim 4). Further, the servo motor is supported by a screw holding member or a pusher plate, and a timing belt is wound around a driven pulley attached to the ball screw shaft between the pusher plate and the ball nut and a drive pulley of the servo motor. It can also be set (Claim 5).

The rear end of the ball screw shaft may be rotatably supported by a bearing of an auxiliary member attached to the pusher plate (claim 6). With this configuration, the ball screw shaft rotates smoothly without lateral swing. Further, it is preferable that the auxiliary member is integrally connected to the pusher plate by a guide rod that is movably inserted into the shaft hole of the fixed plate (claim 7). In this configuration, the assembling strength of the pusher plate and the auxiliary member is enhanced by the fixing plate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In the figure, reference numeral 1 is a screw holding member. A heating cylinder 2 is attached to the center of the front surface (the surface on the left side in the figure) of the screw holding member 1, and a plurality of heating cylinders (2
The fixing plate 4 is integrally connected via a tie rod 3).

A screw holding member 6 and a pusher plate 7 are supported by the tie rods 3 and 3 by inserting the tie rod 3 into respective shaft holes 6a and 7a formed therein. Screw holding member 6 and pusher plate 7
Can move along the tie rods 3, 3.
In the bearing 8 of the screw holding member 6, a screw (injection screw) 9 is rotatably supported by protruding to the front surface of the screw holding member 6, and is inserted into the heating cylinder 2 so as to be able to move back and forth.
An electric motor 11 is fixed to the screw holding member 6 with a bracket 12. The electric motor 11 rotates the screw 9 via the pulley 13, the pulley 14 of the screw 9, and the timing belt 15 wound around them.

A load cell (pressure detector) 17 is attached to the center of the rear surface of the screw holding member 6 with a bolt 18, and a pusher plate 7 is attached to a flat plate 20 attached to the rear surface of the load cell 17 with a bolt 19. It is attached with a bolt 21 with the load cell 17 interposed therebetween.

A flat plate-shaped auxiliary member 24 is integrally connected to the rear surface of the pusher plate 7 through a plurality of (two in the figure) guide rods 23. The guide rod 23 is movably inserted into the shaft hole 4 a of the fixed plate 4, and the pusher plate 7 is attached to the fixed plate 4 with respect to the fixed plate 4.
Also, the auxiliary member 24 can move back and forth. The fixing plate 4, the screw holding member 6, and the shaft holes 4a, 6a, 7a of the pusher plate 7 are formed by guide bushes.

A ball nut 26 is fixed to the center of the front surface of the fixed plate 4 with a bolt 27 by bringing its flange 26a into contact with the front surface of the fixed plate 4, and a ball bearing 26 is mounted on a bearing 28 in the center of the rear surface of the pusher plate 7. The front end of the screw shaft 29 is rotatably supported. The ball screw shaft 29 is screwed to the ball nut 26 with its central axis aligned with the central axis of the screw 9. A servomotor 30 is fixed to the rear surface of the auxiliary member 24, and its output shaft 30a is coupled to the rear end of the ball screw shaft 29 by a coupling 32.
It is directly connected with.

Next, the operation of the injection device of the injection molding machine configured as described above will be described. When the servo motor 30 is operated to rotate the ball screw shaft 29 in the forward direction (the rotation direction in which the ball screw shaft 29 advances), the ball screw shaft 29 advances to the left with respect to the ball nut 26. Since the screw holding member 6 is moved and pushed through the pusher plate 7 and the load cell 17, the screw 9 advances together with the screw holding member 6 and injects the molten resin in the heating cylinder 2 into the molding cavity of the mold. At this time, load cell 17
Is compressed between the screw holding member 6 and the pusher plate 7 to detect the injection pressure.

In the above, the bearing 28 prevents the rotational force of the ball screw shaft 29 from being transmitted to the pusher plate 7 as much as possible, so that the one-side contact of the pusher plate 7 with respect to the tie rods 3 is reduced, and the pusher plate 7 is pushed. The plate 7 moves smoothly without causing power loss. Moreover, since the tie rod 3 completely blocks the rotation of the pusher plate 7, the rotational force of the ball screw shaft 29 is not transmitted to the load cell 17, and the injection pressure can be detected with high accuracy. Further, since the ball nut 26 receives the injection reaction force at the flange 26a, the bolt 27 does not extend and the pressure detection of the load cell 17 is not adversely affected. Further, the fixed plate 4 in which the guide rod 23 is inserted into the shaft hole 4a strengthens the assembly strength of the pusher plate 7 and the auxiliary member 24, prevents the guide rod 23 from being deformed in the radial direction, and prevents the pusher plate 7 and the auxiliary member from being deformed. Smooth the movement of 24.

In the measuring step after the injection step, the screw 9 is retracted together with the screw holding member 6 by a predetermined back pressure while rotating the screw 9 by the electric motor 11 to heat, knead and melt the resin material. , Screw 9
It is well known to weigh the front part of the.

FIG. 2 shows a second embodiment of the present invention.
In this injection device, the rear end portion of the ball screw shaft 29 is rotatably supported by a bearing 35 provided on the auxiliary member 24, and the servomotor 30 is supported by a bracket 36 at a side front position of the auxiliary member 24. It is fixed. Then, the timing belt 39 is wound around the drive pulley 37 of the servo motor 30 and the driven pulley 38 of the ball screw shaft 29 to rotate the servo motor 30.
It is designed to be transmitted to.

In the case of this injection device, the servomotor 30
Is transmitted to the ball screw shaft 29 via the pulleys 37 and 38 and the timing belt 39, and the ball screw shaft 29 is rotated. Since the other structure and operation of this injection device are the same as those of the injection device of FIG. 1, the same members are designated by the same reference numerals and the description thereof is omitted.

In this injection device, the ball screw shaft 2
Since both ends of 9 are supported by the bearings 28 and 35, they smoothly rotate without lateral shake. Further, there is an advantage that the entire length of the auxiliary member 24 is shorter than that of the injection device of FIG. Further, the gear ratio can be changed by changing the diameter ratio of the drive pulley 37 and the driven pulley 38, and the screw 9 can be easily moved at an injection speed suitable for the type of resin, the shape of the molded product, and the like. .

FIG. 3 shows a third embodiment of the present invention.
In this injection device, the rear end portion of the ball screw shaft 29 of the injection device of FIG. 1 is rotatably supported by the bearing 35 of the auxiliary member 24 like the injection device of FIG. Also in this injection device, the ball screw shaft 29 smoothly rotates without lateral shake. Since other structures and operations are the same as those of the injection device of FIG. 1, the same members are designated by the same reference numerals and the description thereof will be omitted.

FIG. 4 shows a fourth embodiment of the present invention.
In the case of this injection device, from the injection device of FIG.
4 and the guide rod 23 are omitted, and the servomotor 30 is fixed to the pusher plate 7 by a bracket 36.
The driven pulley 3 is provided at the tip of the ball screw shaft 29, that is, the portion between the pusher plate 7 and the ball nut 26.
8 is fixed, and a timing belt 39 is wound around the driven pulley 38 and the drive pulley 37 fixed to the output shaft 30a of the servomotor 30.

Also in this injection device, the servo motor 3
By 0, the ball screw shaft 29 is rotated via the pulleys 37 and 38 and the timing belt 39. The absence of the auxiliary member 24 and the guide rod 23 simplifies the structure and shortens the overall length of the device. The direction of the servo motor 30 can be reversed to avoid interference with the electric motor 11, and the servo motor 30 can be fixed to the screw holding member 6. Since other structures and operations are the same as those of the injection device of FIG. 1, the same members are designated by the same reference numerals and the description thereof will be omitted.

FIG. 5 shows a fifth embodiment of the present invention.
In this injection device, the pusher plate 7 is prevented from rotating around the central axis of the ball screw shaft 29 and is fitted into the recess 6b of the screw holding member 6 so as to be movable in the axial direction of the ball screw shaft 29. The most common means for stopping the rotation of the pusher plate 7 with respect to the screw holding member 6 is to form the recess 6 and the pusher plate 7 in a shape other than a perfect circle, but other means may be used. This injection device has a simpler structure than the injection device of FIG. Other structures and operations of the injection device of FIG. 5 are the same as those of the injection device of FIG.

Pulleys 37, 38 and timing pulley 39
It is possible to change the transmission device of FIGS. 2, 4 and 5, which is composed of the following, to a transmission device using a transmission member such as a gear. Further, in the injection device of FIGS. 1 to 3, the guide rod 23 is inserted into the shaft hole 4a of the fixed plate 4 and the auxiliary member 24 is integrally coupled to the pusher plate 7. It may not be inserted into 4a. The position and shape of the bracket 36 are not limited to those shown in the figures, but may be arbitrary. Further, without guiding the screw holding member 6 to the tie rod 3, the rotation around the central axis of the screw 9 is stopped in the recess opened in the front surface of the pusher plate 7 guided by the tie rod 3 to move in the axial direction of the screw 9. You can also fit it freely.

[0027]

As described above, according to the first aspect of the invention, the pressure detector is not affected by the rotation of the ball screw shaft or the extension of the bolt at all, so that the pressure can be detected with high accuracy. be able to. Therefore, it is possible to control the injection process with high precision and perform good molding. Further, since a pressure detector having a special shape such as an annular shape is not required, it is advantageous in terms of cost.

In the injection device of the above injection molding machine, if the pusher plate is movably supported by the tie rod, the pusher plate can be moved smoothly. Further, if the servo motor is supported by an auxiliary member attached to the pusher plate, interference of the servo motor with other electric motors can be avoided, and maintenance and the like can be facilitated. In this case, the servo motor
If the rear end portion of the ball screw shaft is connected via a coupling, the maintenance becomes easier.

Further, the servo motor is supported by a screw holding member or a pusher plate, and a timing belt is wound around a driven pulley attached to the ball screw shaft between the pusher plate and the ball nut and the drive pulley of the servo motor. In the case of the hung configuration, the total length of the device can be shortened. If the rear end portion of the ball screw shaft is rotatably supported by the bearing of the auxiliary member attached to the pusher plate, the ball screw shaft is prevented from lateral runout and smoothly rotates. Further, when the auxiliary member is integrally connected to the pusher plate by the guide rod movably inserted into the shaft hole of the fixing plate, the fixing plate has an effect of strengthening the assembling strength of the pusher plate and the auxiliary member.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 2 is a cross-sectional view showing a second embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 3 is a cross-sectional view showing a third embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 4 is a cross-sectional view showing a fourth embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 6 is a sectional view of an injection device of a conventional injection molding machine.

[Explanation of symbols]

1 Heating Cylinder Holding Member 2 Heating Cylinder 3 Tie Rod 4 Fixed Plate 4a Shaft Hole 6 Screw Holding Member 7 Pusher Plate 9 Screw 17 Load Cell (Pressure Detector) 23 Guide Rod 24 Auxiliary Member 26 Ball Nut 26a Flange 27 Bolt 28, 35 Bearing 29 Ball screw shaft 30 Servo motor 30a Output shaft 32 Coupling 37 Drive pulley 38 Driven pulley 39 Timing belt

Claims (7)

(57) [Claims] 1. A screw holding member having a screw on the front surface moves along a tie rod to a plurality of tie rods provided by integrally connecting a heating cylinder holding member having a heating cylinder attached to the front surface and a fixing plate. A ball screw shaft is screwed to a ball nut that is freely supported and fixed to the fixing plate with its central axis aligned with the central axis of the screw, and the ball screw shaft is rotated to rotate the ball screw shaft. In an injection device of an injection molding machine in which a servomotor for moving the screw holding member along with a screw along a tie rod is connected, a pusher plate is attached to a rear surface of the screw holding member via a pressure detector, An injection device of an injection molding machine, wherein a front end portion of the ball screw shaft is rotatably supported by a bearing of a pusher plate. 2. The injection device of an injection molding machine according to claim 1, wherein the pusher plate is movably supported by a tie rod. 3. The injection device of the injection molding machine according to claim 1, wherein the servomotor is supported by an auxiliary member attached to the pusher plate. 4. The injection motor according to claim 1, wherein the servomotor is supported by an auxiliary member attached to the pusher plate and is connected to the rear end of the ball screw shaft through a coupling. Injection machine of molding machine. 5. A servo motor is supported by a screw holding member or a pusher plate, and a timing belt is wound around a driven pulley mounted on a ball screw shaft between the pusher plate and a ball nut and a drive pulley of the servo motor. The injection device of the injection molding machine according to claim 1 or 2, which is hung. 6. The injection according to claim 1, wherein a rear end of the ball screw shaft is rotatably supported by a bearing of an auxiliary member attached to the pusher plate. Injection machine of molding machine. 7. The auxiliary member is integrally connected to the pusher plate by a guide rod that is movably inserted in the shaft hole of the fixed plate.
Injection device of the described injection molding machine.