JPS60125620A - Detecting method for clamping force - Google Patents

Abstract

PURPOSE:To detect clamping force, by detecting extension of a tie bar between stationary plates. CONSTITUTION:As a tie bar 10 is fixed to stationary plates 1, 2, molds 7, 7' are fixed to a movable plate 3 and the stationary plate 2 and a servomotor M are actuated, it becomes that the movable plate 3 and the mold 7 are moved and clamping of the mold is performed through a nut 5 and a ball screw 4. Resistance wire 8 fixed respectively to the stationary plate 1, 2 is stretched between the stationary plate 1, 2 and a bridge circuit is constituted with a variable resistor R1, resistors R2, R3, an electric power source E and a galvanometer A. Then clamping force becomes detectable as extension of the tie bars 9, 10 is detected due to a fact that when a distance between the stationary plate 1, 2 is displaced, a resistance value of the resistance wire 8 is varied also and this variation is detected by the galvanometer A when clamping of the mold is started.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application and Prior Art The present invention relates to a method for detecting mold clamping force of a mold clamping device in an injection molding machine.

When measuring the mold clamping force in the mold clamping device of an injection molding machine, if it is a direct pressure mold clamping device that clamps the mold using hydraulic pressure, it is possible to measure the hydraulic pressure of the hydraulic cylinder and detect the mold clamping force. In a toggle type mold clamping device, it is not possible to simply detect the current clamping force. In an injection molding machine that uses a toggle type mold clamping device, as the injection force is increased, the mold clamping force also increases in proportion to the injection force, and in particular, when the injection force is higher than the design, the mold clamping force increases extremely. However, accidents such as damage to tie bars and nuts may also occur. Therefore, a conventional method has been to insert a load cell or the like and measure the mold clamping force.

OBJECTS OF THE INVENTION An object of the present invention is to provide a mold clamping force detection method that detects displacement of a fixed plate of a mold clamping device, that is, elongation of tie bars, and then detects mold clamping force.

Structure of the Invention The present invention is a mold clamping force detection method for detecting mold clamping force by detecting elongation of tie bars between fixed plates in a mold clamping device of an injection molding machine.

Embodiment FIG. 1 is a diagram showing a first embodiment of the present invention.
3 is a fixed plate of the mold clamping device of an injection molding machine, and 3 is a movable plate. In this embodiment, the movable plate 3 includes a 1-stroke motor M and a transmission device 6.
．． Natsu 5. A ball screw 4 allows movement in the left and right directions in FIG. 7 and 7' are molds, which are fixed to the movable platen 3 and the fixed platen 2. 9, 10 is one one
D. This is a tie bar fixed to the fixed plate 1°2. Also,
Reference numeral 8 denotes a resistance wire stretched between the fixed plates 1 and 2 and fixed to the fixed plates 1 and 2, respectively, and the resistance wire 8 and the variable resistance R
+, resistors R2 and R3 constitute a bridge circuit. Note that E is a power source and A is a galvanometer.

In the above configuration, the servo motor M rotates, rotates the nut 5 via the transmission device 6, moves the ball screw 4 to the right in FIG. 1, moves the movable platen 3 and the mold 7, and 7' is closed and the mold tightening begins, the fixed platen 2 is pressed from the PII plate 3 via the molds 7 and 7', the tie bars 9 and 10 are extended, and the distance between the fixed plates 1 and 2 is increased. is displaced;
Resistance line 8 also stretches. Therefore, the resistance value of the resistance wire 8 also changes, and the change in A can be detected by the galvanometer A, and the elongation of the resistance wire 8, that is, the elongation of the tie bars 9 and 10 can be detected. Since the mold clamping force on the molds 7 and 7' is generated by the elongation of the tie bars 9 and 10, the mold clamping force is detected by the change in galvanometer A caused by the elongation of the resistance wire 8. 1- It becomes possible to do something.

FIG. 2 shows a second embodiment, which differs from the first embodiment in that a clamping force detection bar 11 is provided instead of the resistance wire 8. Items that are the same as those in the example are denoted by the same reference numerals.In other words, the mold clamping force detection bar 11 has one end fixed to the fixed platen 2, passes through the kite piece 13 on the movable platen 3, It is supported by an elongation detecting section 14 installed on the fixed platen 1. Also, the elongation detecting section 1/1 is
J as shown in FIG. It is designed to slide on the top. Then, by applying a voltage between the terminals a and b of the resistance element 15 and measuring the voltage between one terminal a or b and the slider C, tie bars 9 and 1
It is possible to measure the elongation at zero and the tightening force.

As explained in the first embodiment, the mold is clamped by the servo motor M, the tie bars 9 and 10 are extended, and the mold is clamped (]
When this is performed, the slider C provided on the mold clamping force detection bar 11 slides on the resistance element 15 due to the elongation of the tie bars 9 and 10, that is, the change in the distance between the fixed plates 1 and 2. ,
Therefore, the potential between the slider C and one terminal a or 6 of the resistance element 15 changes. From this change, the elongation of the tie bar, that is, the mold clamping force is detected.

In the above embodiment, the elongation of the tie bar, that is, the tightening force, was detected by the change in resistance value, but the distance between the fixed plates could be measured using other methods such as a laser beam, etc. Alternatively, install a rotation detector with a pinion on one of the fixed plates.Fix a rack that engages with the pinion on the fixed plate in use, and use the detector to detect the elongation of the tie bar and tighten it. The applied force may also be detected.

Effects of the Invention The present invention detects the tightening force by measuring the distance of the fixed plate, that is, the elongation of the tie bar, so the tightening force can be detected with a simple action and the tightening force can be generated. Since this method detects the elongation of the tie bar, it is possible to accurately detect the tightening force.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG. 2 is a diagram showing a first embodiment of the present invention.
FIG. 3, a diagram showing the second embodiment, is a detailed diagram of the elongation detection section in the second embodiment. 1.2...Fixed plate, 3...Movable plate, 7.7'...
Mold, 8... Resistance wire, 9, 10... Tie bar, 11
... Mold clamping force detection bar, 14... Elongation detection section. −〇−

Claims (3)

[Claims] (1) A mold clamping force detection method for detecting mold clamping force by detecting the elongation of tie bars between fixed plates in a mold clamping device of an injection molding machine. (2) The mold clamping force detection method according to claim 1, wherein the mold clamping force is detected by a change in resistance value due to elongation of a resistance wire stretched between the fixed plates. (3) A resistance element is fixed to one fixed plate, a detection rod is fixed to the other fixed plate, and the wiper fixed to the detection rod slides on the resistance element, so that the wiper can be obtained from the wiper. The method for detecting mold clamping force according to claim 1, wherein elongation of the tie bar is detected from a change in resistance value to detect mold clamping force.