JPS6135924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding machine having a toggle type mold clamping device, and more particularly to a method for automatically adjusting and setting the required mold clamping force of a molding die.

Normally, the mold clamping force of the mold of an injection molding machine having a toggle-type mold clamping device is determined by how many mm the tie bars (usually four) are extended by the toggle, and the setting is performed as follows. That is, as shown in FIG. 1, the zero point position is adjusted by bringing the molds 7 and 8 into contact with each other with the toggle fully extended, then retracting the toggle to stop it, and then tightening the tie bar 6 on the side of the mold clamping housing 3. By rotating the tie nut 17 that is screwed into the threaded part 6a provided at the end, the mold clamping housing 3, the short link attachment part 13,
Short link 11, long link 9, long link attachment part 1
2. When the entire toggle device consisting of the movable platen 2, crosslink 10, crosshead 14, mold clamping cylinder 4 (piston 16, piston rod 15), etc. is moved a predetermined amount in the direction of the fixed platen 1 along the tie bars 6. The mold clamping force is set by stopping the rotation of the tie nut 17. In addition,
5 is a fixed side tie nut. In addition, as means for rotating the tie nut 17, a worm method using an input is used for small machines, a worm method using an electric motor or hydraulic motor, a chain method, a large gear method, etc. are used for large machines, and a predetermined movement of a toggle device is used. The quantity is usually detected by converting the rotational speed of the tie nut 17 into a voltage value or pulse number using a potentiometer or a pulse generator (encoder).

Next, a conventional automatic mold clamping force setting method will be explained in detail with reference to FIG. When replacing a thin mold with a thick mold, first remove the thin molds 7 and 8 from the fixed plate 1 and the movable plate 2, and then move the movable plate 2 backward by operating the mold clamping cylinder 4 to open the mold. After introducing thick molds 7' and 8' between the fixed platen 1 and the movable platen 2 instead of the thin molds 7 and 8, the movable platen 2 is moved forward by operating the mold clamping cylinder 4, and the molds are moved with low hydraulic pressure. Close the mold by pressing it against the fixed platen 1 (see Fig. 2), and press the mold 7',
8' are respectively attached to the fixed platen 1 and the movable platen 2 with bolts or the like. Thereafter, the movable platen 2 with the mold 8' attached thereto is moved backward by operating the mold clamping cylinder 4, and the tie nut 17 is rotated by rotating the worm shaft (see Fig. 7) using an electric motor, hydraulic motor, etc. to move the entire toggle device backward and away from the fixed platen 1. During this process, the mold clamping cylinder 4 is operated with low oil pressure to perform mold closing operation. The rotational speed of the tie nut 17 is converted into a voltage value or pulse number by a potentiometer, pulse generator, etc. and input to the controller, and the input signal value becomes a predetermined value, and the short link 11 and long link 9 are fully extended. In this state, the forward and backward movement of the toggle device and the mold opening/closing operations are repeated in response to signals output from the controller until a slight gap is created between the molds 7' and 8'. When the toggle is fully extended and there is a gap between the molds 7' and 8', next short link 1
1. While the long link 9 is fully extended, rotate the worm shaft in the opposite direction to the above to remove the tie bolt 17.
is reversed to move the entire toggle device forward, and when a sensor or the like detects an increase in oil pressure or an increase in current value when the molds 7' and 8' come into contact, the rotation of the tie nut 17 is stopped. That is, the rotation of the tie nut 17 is stopped when the zero point position is determined. In this state, even if the mold clamping cylinder 4 is operated with high hydraulic pressure to clamp the mold, the molds 7' and 8' are only in contact and no clamping force is generated. Next, the mold clamping cylinder 4 is operated once to open the mold, and the tie nut 17 is rotated to advance the entire toggle device by a predetermined amount toward the fixed platen 1, thereby completing the setting of the mold clamping force. This predetermined amount is calculated in advance from the amount of tie bar extension that provides the mold clamping force, and is set by the number of rotations of the worm shaft, that is, the number of rotations of the tie nut 17.

In addition, when replacing thick molds 7', 8' with thin molds 7, 8, after removing the thick molds 7', 8', the first time the mold is closed, the toggle should be fully extended and the entire toggle device The fixed platen 1 is moved forward until the distance between the fixed platen 1 and the movable platen 2 becomes smaller than the thickness of the thick molds 7' and 8'. Thereafter, after attaching the thin molds 7 and 8, the mold clamping force is set in the same manner as described above.

As mentioned above, in the conventional automatic mold clamping force setting method when replacing the mold, the toggle device must be moved forward and backward many times and the mold opening and closing operations must be repeated many times before the zero point position is obtained, and the automatic setting time is It has the disadvantage that it takes a long time.

In addition, when molding is performed using a mold with a hydraulically operated core, there are many structural types, and there are various ways to set the timing of the core's operation.For example, there are types in which the core is inserted before the mold is closed, There are types that insert the core into the mold, types that insert the core while closing, types that remove the core before opening the mold, types that remove the core after opening, and types that remove the core while opening.In total, there are types that insert the core into the mold (3 types) and types that remove the mold (3 types). There are 9 types of combinations (3 types), but if the timing of this operation is incorrect, the mold will be damaged in most cases. Therefore, in the conventional automatic mold clamping force setting method, since the mold is opened and closed many times, the hydraulic core must be operated at a predetermined timing each time, so it is necessary to operate the hydraulic core at a predetermined timing each time. The drawback was that the secondary hydraulic piping and electrical wiring had to be completed in advance.

The present invention has been made to solve the above-mentioned drawbacks, and first, a first implementation method of the present invention will be explained with reference to FIGS. 2 and 3.

In this first embodiment method, a plurality of limit switches are installed in the mold clamping housing 3 via a bracket 18 to obtain a mold clamping force that is gradually smaller than the rated mold clamping force, for example, a limit switch 19a to obtain the rated mold clamping force. A limit switch 19b for obtaining a mold clamping force smaller than the rated mold clamping force, and a limit switch 19c for obtaining the minimum (0 ton) mold clamping force (mold clamping force at the zero point position) are provided, and the mold clamping cylinder 4 These limit switches 19a to 19c are installed at the tip of the piston rod 15.
A striker 20 is provided for sequentially operating the . Limit switch 19a is striker 20
The bracket 18 is fixed at a position where the rated mold clamping force is generated when the molds 7' and 8' are in contact with each other and the molds are clamped using high pressure oil. Limit switch 19b
is its operating position, and the bracket 18 is fixed at a position where a mold clamping force smaller than the rated mold clamping force is generated when the mold is similarly clamped, and the toggle of the limit switch 19c is fully extended as shown in the third figure. Needless to say, it is fixed at a position where it can be operated by the striker 20 (a position where a mold clamping force of 0 tons can be obtained). Therefore, if n limit switches are installed, the rated mold clamping force is N.
(for example, 150 tons), the mold clamping force can be set in n steps from N=150 tons to 0 tons.

First, the thin molds 7 and 8 are removed from the fixed platen 1 and the movable platen 2, and then the movable platen 2 is moved back by operating the mold clamping cylinder 4 to open the mold, and the fixed platen 1 and the movable platen 2 are removed.
In between, instead of thin molds 7 and 8, thick molds 7',
After carrying in the molds 7' and 8', the movable platen 2 is advanced by operating the mold clamping cylinder 4 and pressed against the fixed platen 1 with low hydraulic pressure to close the mold, and the molds 7' and 8' are separated from the fixed platen 1 and the movable platen 2. The molds 7' and 8' are respectively attached to the fixed platen 1 and the movable platen 2 with bolts, die clampers, etc. while holding the molds 7' and 8'. FIG. 2 shows how the molds 7' and 8' are installed. After that, automatic mold clamping force setting of the present invention starts. From the state shown in Fig. 2, low pressure oil (pressure 10 to 15 kg/cm ²
a small mold clamping force (in this case, the contact force between molds 7' and 8') in the direction of extending the toggle.
is applied to the molds 7', 8' so that these molds 7', 8' do not separate, and the tie bolt 17 is moved in a direction that moves the entire toggle device backward, in other words, away from the fixed platen 1. By rotating in the direction, the toggle consisting of the short link 11, long link 9, etc. is gradually extended, and the piston rod 15 of the mold clamping cylinder 4 is advanced relative to the mold clamping housing 3, and the piston rod 15 is moved forward. The limit switches 19a to 19c were operated in sequence, and the limit switch was operated by the striker 20 provided on the piston rod 15 to obtain a mold clamping force that matched the mold clamping force preset on the control panel (not shown). For example, if you set the rated mold clamping force on the control panel at the time, limit switch 1
If the mold clamping force is set to be smaller than the rated mold clamping force when the limit switch 9a is activated, the pressure oil to the mold clamping cylinder 4 is cut off and the rotation of the tie nut 17 is stopped at the same time when the limit switch 19b is activated. Set the mold clamping force, for example, the rated mold clamping force or a mold clamping force smaller than the rated mold clamping force. When replacing thick molds 7' and 8' with thin molds 7 and 8,
After removing the thick molds 7' and 8', tie bolts 1 are attached in advance.
7 and move the toggle device to the fixed platen 1 side, molds 7 and 8 with a thin gap between the fixed platen 1 and the movable platen 2
The thin molds 7 and 8 are attached after making the thickness smaller than the thickness of the mold, and then the mold clamping force can be set in the same manner as described above.

This completes the automatic setting of the mold clamping force according to the first implementation method of the present invention, but if high pressure oil is supplied to the cylinder chamber on the piston head side of the mold clamping cylinder 4 after setting, the set mold clamping force can be generated. I can do it. According to this first implementation method, the mold clamping force can be set in stages.

Further, in the first implementation method described above, a case was described in which a plurality of limit switches 19a to 19c were used, but only one limit switch is used to obtain the required mold clamping force, and when this limit switch is activated, the low pressure oil is shut off. Alternatively, the rotation of the tie nut 17 may be stopped, and in this case, only the required mold clamping force can be set.

The method of the invention can also be carried out using a rack and pinion. Figures 4 and 5 are examples,
Attach the rack 2 to the piston rod 15 of the mold clamping cylinder 4.
1, and a mold clamping force signal generating device (such as a potentiometer or a pulse generator (encoder)) that outputs a mold clamping force signal corresponding to the amount of movement of the piston rod 15 to a pinion 22 meshed with this rack 21. (not shown), and after installing the replaced mold, supply low pressure oil to the cylinder chamber on the piston head side of the mold clamping cylinder 4 to prevent the mold from coming off, and then tighten the tie bolt 17. By rotating the entire toggle device in the backward direction, the toggle is gradually extended, and the mold clamping cylinder 4
The piston rod 15 is moved forward relative to the mold clamping housing 3, and the forward movement of the piston rod 15 operates the mold clamping force signal generating device via the rack 21 and pinion 22. The mold clamping force signal is input to the control panel and compared with a preset mold clamping force signal, and when both signals match, the mold clamping force is set by shutting off the low pressure oil and simultaneously stopping the rotation of the tie nut 17. This is the way to do it. According to this second implementation method, the mold clamping force can be set continuously.

Furthermore, the method of the present invention can also be practiced using a limit switch and a multi-strip cam. FIG. 6 is an enlarged explanatory view of the main parts. A limit switch 19' is attached to the bracket 18 protruding from the mold clamping housing 3, and a multi-thread cam 23 is attached to the crosshead 14. After installing the replaced mold, , while supplying low pressure oil to the cylinder chamber on the piston head side of the mold clamping cylinder 4 to prevent the mold from detaching.
By rotating the tie nut 17 in a direction that moves the entire toggle device backward, the toggle is gradually extended and the crosshead 14 connected to the piston rod 15 of the mold clamping cylinder 4 is moved relatively forward, and by this forward movement, the toggle is attached to the crosshead 14. When the number of times the multi-threaded cam 23 hits the limit switch 19' matches the number of times the limit switch is operated, which is set in advance by a counter, the low pressure oil is cut off and at the same time the rotation of the tie bolt 17 is stopped. This can be a method of setting the mold clamping force. In this method, the amount of movement of the crosshead 14 is controlled by a potentiometer,
Continuous detection is possible using an encoder, etc., and when this detection signal (mold clamping force signal corresponding to the amount of movement) matches the mold clamping force signal set on the control panel, the low pressure oil is shut off and at the same time the tie bolt 17 is rotated. It is also possible to set the mold clamping force continuously by stopping the process.

The drive mechanism for rotating the tie nut 17 in the method of the present invention can be constructed using conventional techniques, for example, as shown in FIG. The rotational drive mechanism of the tie nut 17 rotates a worm shaft 27 via gears 25 and 26 by a drive source 24 such as a hydraulic motor or an electric motor, and a worm wheel 17a formed on the outer periphery of the worm shaft 27 and the tie nut 17 rotates the worm shaft 27 through gears 25 and 26. The tie nut 17 is rotated by the engagement of the two. In addition, a mold clamping force signal is input to the control panel, and when this input signal and a mold clamping force signal preset in the control panel match, the low pressure oil in the mold clamping cylinder 4 is shut off by operating a switching valve, and the tie bolt 17 is shut off. The configuration of a control panel that outputs a signal to stop rotation can also be achieved using conventional techniques, and the method of the present invention uses these, but the configuration is not the gist of this, so we will not explain it. Omitted.

As is clear from the above explanation, according to the method of the present invention, unlike the conventional automatic mold clamping force setting method when the mold is replaced, the toggle device has to be moved forward and backward many times until the zero point position is obtained. Since there is no need to repeat the mold opening/closing operation, the automatic setting time can be shortened, which in turn can shorten the mold exchange time, leading to an effect of improving productivity. There is no need to repeatedly open and close the mold, and the mold clamping force is set while the mold is closed, so even if the mold has a hydraulically operated core, there is no need to operate the core at a predetermined timing. There is an advantage that it is not necessary to complete the hydraulic piping, electrical wiring, etc. of the core before starting the automatic setting of the mold clamping force, and the piping, wiring, etc. can be done after the mold clamping force is set.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the zero point position adjustment of a thin mold in a toggle type mold clamping device using an example of the conventional method, and Fig. 2 is an explanatory diagram of a toggle type mold clamping device using the first embodiment of the method of the present invention. FIG. 3 is an explanatory diagram showing the installation state of a thick mold. FIG. 3 is an explanatory diagram when adjusting the zero point position of a thick mold. FIG. An explanatory diagram showing the installation state of the mold, Fig. 5 is an explanatory diagram when adjusting the zero point position of a thick mold, and Fig. 6 is a main part of a toggle type mold clamping device to which the third embodiment of the method of the present invention is applied. FIG. 7 is an explanatory diagram of the rotational drive mechanism of the tie nut in the present invention. 1... Fixed plate, 2... Movable plate, 3... Mold clamping housing, 4... Mold clamping cylinder, 6... Tie bar, 6
a...Threaded part, 7, 8...Thin mold, 7', 8'...
... Thick mold, 9 ... Long link, 10 ... Cross link, 11 ... Short link, 14 ... Cross head, 15 ... Piston rod, 16 ... Piston, 17 ... Tie bolt, 17a ... Worm wheel, 18 ...Bracket, 19a-19
c, 19'... Limit switch, 20... Striker, 21... Rack, 22... Pinion, 2
3... Multi-strip cam, 24... Drive source, 25, 26...
...gear, 27...worm shaft, 27a...worm.

Claims (1)

[Claims] 1. In a method of automatically setting the mold clamping force when the mold is replaced, a means is provided to obtain a mold clamping force signal corresponding to the amount of advance of the piston rod of the mold clamping cylinder, and After installation, while supplying low pressure oil to the cylinder chamber on the piston head side of the mold clamping cylinder to prevent the mold from detaching, gradually extend the toggle by rotating the tie nut in a direction that moves the entire toggle device backwards. At the same time, the piston rod of the mold clamping cylinder is advanced relative to the mold clamping housing, and when a mold clamping force signal corresponding to the amount of advance is obtained by the means, the low pressure oil is shut off and at the same time the rotation of the tie nut is stopped. An automatic mold clamping force setting method for a toggle type injection molding machine, characterized in that the mold clamping force is set by setting the mold clamping force.