JPH043782Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a Kunitzking variable toggle type mold clamping device for an injection molding machine.

(Prior Art and its Problems) In a conventionally known toggle type mold clamping device, as shown in FIG. 2, one end of a tie rod 3 passing through a fixing plate 1 is fixed to the fixing plate 1 with a fixing nut 2. This tie rod 3 is connected to a movable plate 4 via a bush 5.
is fitted in a slidable manner, and the movable plate 4 is fitted with a toggle lever 7 and toggle pins 6a, 6b, 6c.
is connected to the toggle support 8 via the
Toggle lever 7 and toggle pins 6a, 6b, 6c
tie rod 3 by mold clamping cylinder 13 via
It is now possible to move along. 21 and 22 are molds for molding, and are provided facing the fixed plate 1 and the movable plate 4.

Reference numeral 11 denotes an adjustment gear, which is fixed to the adjustment nut 10. When changing the mold clamping force and the thickness of the molds 21 and 22, the four adjustment gears 11 are adjusted by an idling gear 12 meshing with the adjustment gear 11. Rotate to adjust the position of the toggle support 8. Therefore, for example, in order to reduce the mold mounting thickness, if the adjusting gear 11 is rotated clockwise, the adjusting nut 10
hits the end face of the toggle support 8 and moves the toggle support 8 forward.

When the distance between the fixed plate 1 and the toggle support 8 is fixed and the mold clamping cylinder 13 is operated in the mold clamping direction, the toggle lever 7 is extended, and the movable plate 4 and the mold 2
1 and 22 to widen the gap between the fixed plate 1 and the toggle support 8, a force in the tensile direction acts on the four tie rods 3, and a force that tightens the mold (mold clamping force) acts as a reaction force. occurs. On the other hand, when the thickness of the molding molds 21 and 22 increases due to thermal expansion during molding, the tensile stress of the tie rod 3 increases and the mold clamping force increases. In such a case,
Toggle support 8 by adjusting the conventional adjustment nut 10
However, with this method, it is difficult to adjust the adjustment nut 10, and it is difficult to adjust the mold clamping force minutely by adjusting the position of the toggle support 8. .

(Purpose of the invention) In general, the maximum mold clamping force of a toggle type mold clamping device is determined by the output of the mold clamping cylinder 13 and the amount of clamping (clinching is defined as the center line a, b of the toggle pins 6a, 6b from the center c of the toggle pin 6c to the center line a, b of the toggle pins 6a, 6b. This is the length A of the perpendicular line drawn to connect the toggle.This knitting is determined by the fully extended position of the toggle, that is, the stroke end position on the mold clamping side of the mold clamping cylinder, and the crosshead position is adjusted semi-fixed. ).

On the other hand, injection molding machines are capable of stable, high-quality molding without being affected by external disturbances, but various devices are involved in producing stable molded products. In conventional mold clamping devices, changes in mold clamping force occur during molding operation, and this is strongly related to the quality of the molded product, so a toggle type that can reduce the change in mold clamping force during molding operation as much as possible. A mold clamping device is needed.

In light of the above circumstances, the present invention aims to provide a toggle type mold clamping device that can minimize changes in mold clamping force during molding operation.

(Solution by invention) In the toggle type mold clamping device, the mold clamping cylinder 13
A guide bar 17 is attached to the tip of the piston rod 14.
Attach the crosshead 15 guided by the
The stroke end position of the crosshead 15 can be regulated by a stopper nut 18 screwed into a threaded portion 17a provided at the end of the guide bar 17. The position of the stopper nut 18 is adjusted by rotating the stopper nut 18 from a servo motor 20 via a power transmission mechanism such as a power transmission chain 19 and a sprocket wheel 19a, and the mold clamping is performed by changing the knitting amount A by moving the stopper nut. Force can be adjusted.

(Example) Hereinafter, description will be given with reference to FIG. 1. Reference numeral 14 designates a piston rod of the mold clamping cylinder 13, and a crosshead 15 is fastened to the tip of this piston rod with a tightening nut 16. The crosshead 15 moves guided by two guide bars 17. The crosshead 15 is regulated by a stopper nut 18 which is screwed into a threaded portion 17a provided at the end of the guide bar 17 of the crosshead 15. And this stopper nut 1
The position 8 is adjusted by rotating the stopper nut 18 by a servo motor 20 via a power transmission chain 19. By adjusting the stopper nut 18 to change the clamping force, the mold clamping force changes. That is, when the stroke end position of the crosshead 15 moves to the right in FIG. 1, the amount of pinching becomes smaller and the mold clamping force becomes larger.

Note that by rotating the stopper nut 18 using the servo motor 20, the control can be easily automated, such as by feedback control of the mold clamping force.

(Function) Next, the function of the same structure as the known toggle type mold clamping device will be explained with reference to FIG. 2.

In FIG. 2, a molding die 21 is mounted on the fixed plate 1.
The molding molds 22 are respectively attached to the movable plate 4, and the mold clamping cylinder 13 is operated to remove the crosshead 15, toggle pins 6, 6a, 6b, 6c, and toggle lever 7.
The movable plate 4 is moved toward the fixed plate 1 via the movable plate 4 to generate mold clamping force. Molding molds 21, 2 during molding operation
When the mold clamping force increases (changes) due to thermal expansion, etc., the change in mold clamping force is detected and fed back to the servo motor 20 to control the servo motor 20. The servo motor 20 is connected to the power transmission chain 19
Then, rotate the stopper nut 18 to change the stroke end position of the crosshead 15. That is, when the servo motor 20 is controlled clockwise, the position of the crosshead 15 changes, the amount of knitting increases, and the mold clamping force decreases. Servo motor 20
The control detects changes in mold clamping force using the best mold clamping force as a reference value during molding, compares the detected value with the reference value, and controls so that the detected value is equal to the reference value, so that the mold clamping force remains constant. Control so that

(Effects) This invention detects changes in mold clamping force during molding operation, drives a servo motor, controls the position of the stopper nut, and changes the stroke end position of the crosshead, thereby increasing the amount of knitting A. Since the mold clamping force is adjusted by changing the mold clamping force, the clamping force can be finely adjusted according to changes in the mold clamping force even during molding operation of the injection molding machine, and a stable molded product can be obtained.

[Brief explanation of the drawing]

Fig. 1 shows a variable kunitzking device according to the present invention installed at the tip of a mold clamping cylinder. Figure 2 shows a known toggle type mold clamping device. In the figure, A...knitting, 1...fixing plate, 2...fixing nut, 3...tie rod, 4...
...Movable plate, 5...Button, 6a-6c...Toggle pin, 7...Toggle lever, 8...Toggle support, 9...Nut holder, 10...Adjusting nut,
11... Adjustment gear, 12... Idling gear,
13... Mold clamping cylinder, 14... Piston rod, 15... Crosshead, 16... Tightening nut, 17... Guide bar, 18... Stopper nut, 19... Power transmission chain, 20... Servo motor, 21... ...Molding mold, 22...Molding mold.

Claims (1)

[Scope of utility model registration request] In the toggle type mold clamping device, the mold clamping cylinder 13
A guide bar 17 is attached to the tip of the piston rod 14.
Attach the crosshead 15 guided by the
The stroke end position of the crosshead 15 can be regulated by a stopper nut 18 screwed into a threaded portion 17a provided at the end of the guide bar 17, and the position of the stopper nut 18 is adjusted by a servo motor 20 and a power transmission mechanism 19, 19a. A toggle-type mold clamping device characterized in that the clamping force is adjusted by rotating the stopper nut 18 through the stopper nut, and changing the clamping amount A by moving the stopper nut.