JPH051126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a nozzle touch mechanism that brings a nozzle into pressure contact with a mold of an injection molding machine.

Prior Art The nozzle touch mechanism in conventional injection molding machines uses a hydraulic cylinder to press the nozzle against the mold using hydraulic pressure. It is necessary to press the nozzle against the mold at a constant pressure, but when hydraulic pressure is used, a constant pressure is always maintained by switching valves. However, when attempting to drive the nozzle touch mechanism with a motor, it is necessary to maintain a constant pressure at all times.
The disadvantage is that it is necessary to keep a constant current flowing through the motor at all times, or even when the current to the motor is cut off and the brake is applied, once the motor shaft rotates for some reason, it is no longer held at a constant pressure. It was hot. Therefore, the driving force of the motor is transmitted to the injection unit via the spring to press the nozzle against the mold, and even if some external force is applied to the injection unit, the spring absorbs that external force, and the nozzle is always held against the mold. A method of holding by pressure was developed (Japanese Patent Application No. 114433/1984, etc.).

Problems to be Solved by the Invention The present invention provides a nozzle touch mechanism in which the driving force of the motor is transmitted to the injection unit via a spring to press the nozzle against the mold. A gear is used to drive a ball screw, and the ball nut that the ball screw screws into is moved in the axial direction to move the injection unit via a spring and press the nozzle against the mold. Therefore, there is a drawback that the installation position of the motor etc. is restricted and an optimal layout cannot be obtained.
In addition, since the nozzle presses the mold, the fixed plate to which the mold is fixed is caused to bend around the base and the fixing point where the fixed plate is fixed (this also applies to conventional hydraulic systems). ). Therefore, the present invention aims to improve the above-mentioned drawbacks.

Means for Solving the Problems The present invention rotates a ball screw through a transmission mechanism by the rotation of a motor, moves a ball nut screwed with the ball screw, and controls the movement of the ball nut through a spring. In a nozzle touch mechanism that transmits power to the injection unit to press the nozzle into contact with the mold, the transmission mechanism is composed of a pulley and a timing belt that transmit the rotation of the motor to the ball screw. The above problem was solved by fixing the mold to a fixed plate.

Operation Rotation of the motor is transmitted to the ball screw by the pulley and timing belt, the ball nut screwed into the ball screw moves in the axial direction of the ball screw, and the movement of the ball nut is transmitted to the injection unit via the spring. It is transmitted to
Press the nozzle into contact with the mold and release it. Also, since the transmission mechanism from the motor to the ball screw is fixed to the stationary platen on which the mold is attached, the reaction force of the force of the nozzle pressing against the mold is transmitted to the stationary platen via the transmission mechanism. , the fixed plate is less likely to be bent. Furthermore, since the transmission mechanism uses a pulley and a timing belt, the installation position of the motor can be freely selected.

Embodiment FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1 with the injection unit removed, and FIG. 3 is a detailed view of the transmission mechanism. Injection unit, 2 is a heating cylinder, 3 is a nozzle provided at the tip of the heating cylinder, 4 is a fixed plate to which a mold is attached, 5 is an extruder base that slides on a rail 6, The above-mentioned injection unit 1 is fixed to. 7 is a transmission mechanism fixed to the stationary plate 4, 8 is a motor, 9 is a ball screw, 10 is a ball nut into which the ball screw is screwed, 11 is a first plate fixed to the ball nut 10, 12 is the second plate, 13, 13 is the spring, 1
4 and 14 are shafts, and 15 is a base.

Next, the transmission mechanism 7 will be explained in detail with reference to FIG. A first bearing body 30 is fixed to the fixed platen 4, and a second bearing body 31 is fixed to the fixed platen 4 by means of an extension member 32 of the first bearing body 30 with bolts or the like. A motor 8 is fixed to the second bearing body 31. A first rotating shaft 21 of the motor shaft 20 of the motor 8 is rotatably fixed by a bearing B through a coupling member 22, and the first rotating shaft 21
A pulley 23 is fixed to 1. Further, a second rotating shaft 26 is rotatably fixed to the first bearing body 30 by a bearing B, and the second rotating shaft 26 is rotatably fixed to the first bearing body 30 by a bearing B.
A pulley 25 is fixed to the pulley 2.
A timing belt 24 is stretched between the parts 3 and 25. The second rotating body 26 is shown in FIG.
As shown in Figure 2, there is a ball screw 9 at the other end.
is fixed. A ball nut 10 is screwed into the ball screw 9, and a first plate 11 is fixed to the ball nut 10.
Two shafts 14, 14 are fixed to the plate 11, and a second shaft is attached to the other end of the shafts 14, 14.
A plate 12 is fixed. The first plate 11 is in contact with the end of the extruder base 5, and the shafts 14, 1
4 passes through a hole 33 provided at the end of the extruder base 5, and the shafts 14, 14 have the end of the extruder base 5 and the second
A spring 13 is provided between the plates 12. Further, the ball screw 9 is connected to the end of the extruder base 5 of the first plate 11,
Holes 34 and 3 respectively provided in the second plate 12
5 and 36, and protrudes to the left in FIG.

Note that 37 is a sensor fixed to the extruder base 5, which detects the first plate and detects when the nozzle 3 is properly pressed against the mold.

The operation of this embodiment having the above configuration will be described next.

First, in order to press the nozzle 3 against the mold, the motor 8 is driven and rotated in the forward direction, which rotates the first rotating shaft 21, which then passes through the pulley 23, timing belt 24, and pulley 25 to the second rotating shaft 26. rotate in the forward direction. When the second rotating shaft 26 rotates forward, the ball screw 9 rotates forward, causing the ball nut 10 screwed into the ball screw 9 to move forward (to the right in FIGS. 1 and 2). 1
Since the first plate 11 fixed to 0 also moves forward and the shafts 14, 14 fixed to the first plate 11 also move forward, the shafts 14,1
4 is also moved forward, and the second plate is fixed to
The plate 12 presses the springs 13, 13 and presses the end of the extruder base 5 via the springs 13, 13, so the extruder base 5 slides on the rail 6 and The fixed injection unit 1 is advanced to bring the nozzle 3 into contact with the mold. Even if the nozzle 3 contacts the mold, if the motor 8 is further driven, the ball nut 10 and the first and second plates 11 and 12 will move forward even though the extruder base 5 is stopped. The springs 13, 13 are compressed by the plate 12 of No. 2, and the reaction force due to this compression is transmitted to the extruder base 5.
This becomes the force that presses the nozzle 3 against the mold. Then, the sensor 37 detects the first plate, and the drive of the motor 8 is stopped based on this signal. That is, the sensor 37 causes the spring 1 to
3 and 13 are detected, and when the appropriate compression amount, that is, the appropriate pressing force is reached, the sensor 37 detects the first plate 11 and stops the motor 8.

Next, in order to remove the nozzle 3 from the mold, the motor 8 is rotated in the opposite direction, and the first rotating shaft 2 is rotated in the same manner as described above.
1. Reverse the ball screw 9 through the pulley 23, timing belt 24, pulley 25, and second rotating shaft 26, and move the ball nut 10 and first plate 11 backward (to the left in FIGS. 1 and 2). ). Therefore, the first plate 11 presses the end of the extruder base 5, causing the extruder base 5 and the injection unit 1 to retreat, and the nozzle to separate from the mold.

As described above, the present invention provides springs 13, 1
Since the nozzle 3 is pressed against the mold by the compression force of 3, even if some external force is applied, it is instantly absorbed by the springs 13, 13, and then it recovers, so that the mold is always kept at a constant level. The pressing force of the nozzle can be obtained.

In addition, since the nozzle 3 presses the mold, as shown in FIG. Since the motor 8 and the transmission mechanism 7, which are the driving source for pressing the mold, are fixed to the fixed platen 4, the force of the nozzle 3 pressing against the mold, that is, the force of the springs 13, 13 pressing the extruder base 5, is As a reaction force, the second plate 12, the shafts 14, 14, and the first plate 1
1. A force is transmitted to the transmission mechanism 7 via the ball nut 10, the ball screw 9, and the rotating shaft 26, and is applied to the stationary platen 4 to cause the stationary platen 4 to deflect in a counterclockwise direction. Therefore, the force from the nozzle 3 is applied to the fixed platen 4 from the transmission mechanism 7, which is opposite in direction and has an almost equal magnitude, so the force that causes the fixed platen to flex is small, and the fixed platen is deflected. becomes smaller.

In the above embodiment, the spring was compressed and the reaction force caused by the compression pressed the nozzle against the mold, but it is also possible to stretch the spring and press the nozzle against the mold by the tensile force generated at that time. It's okay. Further, in the above embodiment, the amount of compression of the spring, that is, the pressing force of the nozzle against the mold is detected by the sensor 37. Since the driving current of the motor increases when the pressurizing force increases when the pressurizing force comes into contact with the mold, the appropriate pressing force may be detected based on this driving current value.

Furthermore, the motor may be a servo motor, and a position detector of the servo motor may detect the point of appropriate pressing force.

Effects of the Invention As described above, the present invention uses a timing belt to transmit the driving force from the motor to the ball screw that moves the injection unit, so the installation position of the motor is not limited and can be placed arbitrarily. , and because this fixes the transmission mechanism to the fixed platen to which the mold is fixed, the force from the nozzle that is applied to the fixed platen is applied to the fixed platen as a reaction force via the transmission mechanism, so the amount of deflection of the fixed platen becomes smaller,
Molded products with higher precision can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a plan view of FIG. 1 with the injection unit removed, and FIG. 3 is a detailed view of the transmission mechanism. 1... Injection unit, 2... Heating cylinder, 3
... Nozzle, 4 ... Fixed plate, 5 ... Extruder base, 6 ... Rail, 7 ... Transmission mechanism, 8 ...
...Motor, 9...Ball screw, 10...Ball nut, 11...First plate, 12...
Second plate, 13... Spring, 14...
Shaft, 15... Base, 21... First rotating shaft, 23, 25... Pulley, 24... Timing belt, 26... Second rotating shaft, 37... Sensor.

Claims (1)

[Claims] 1 The rotation of the motor rotates the ball screw via the transmission mechanism, moves the ball nut screwed into the ball screw, transmits the movement of the ball nut to the injection unit via the spring, and connects the nozzle to the mold. In the nozzle touch mechanism configured to contact and press, the transmission mechanism is composed of a pulley and a timing belt that transmit the rotation of the motor to the ball screw, and the transmission mechanism is fixed to a fixed plate to which the mold is attached. A nozzle touch mechanism in an injection molding machine characterized by: