JPS5889Y2 - Weighing device for injection molding machine - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a measuring device for an injection molding machine that uses a phototube to measure a synthetic resin material.

In an in-line screw type injection molding machine, when the screw integrated with the injection ram is rotated while the nozzle is in contact with the mold or the valve is closed, the molten material is stored at the front of the injection cylinder. At the same time, the screw retreats.

Generally, the above process is called material metering, and when the injection ram, which has retreated together with the screw, reaches a predetermined position, a limit switch is activated, stopping the rotation of the screw and completing metering.

In metering using such means, the retracting distance of the screw is limited to the distance between the screw and the secondary injection pressure switching limit switch, so it is necessary to change the distance between the limit switches each time the injection material changes.

Also, since positioning the limit switch requires experience, recent attempts have been made to control weighing with a preset counter using a phototube or the like.

This idea sets the screw retraction value for each injection material in advance, and when the number of signals from the phototube generated as the screw retracts reaches the set value, the screw retraction is stopped and measurement is completed. The measuring device is configured so that

This invention will be explained in detail below using illustrated examples.

Reference numeral 1 denotes a base, and holding plates 2, 2 are provided oppositely on both sides of a space 1a in the base plane, and a pair of guide rods 3, 3 are horizontally fixed in parallel across the holding plates 2, 2. .

The guide rods 3, 3 are provided with a transmission plate 5 protruding from the back side that connects to the side of the injection ram 4 connected to the screw, and a rack 6 with teeth formed on the lower side is arranged parallel to the guide rods 3, 3. A movable plate 7 protruding from the side is arranged to straddle the rack 6 so as to slide in the front and back direction with the rack 6 facing inside.

8 is a pinion that meshes with teeth formed on the lower side of the rack 6, and is rotatably supported on the base 1 side with a shaft 9;
And on the outer end surface there is a circular measuring plate 1 made of transparent synthetic resin.
0 is the same center and is a screw stopper.

The surface of this measuring plate 10 is coated with a light-shielding coating in which a large number of slits 11 are formed at regular intervals along the periphery, and the light emitting part 12 a of the phototube device 12 fixed to the base 1 side faces the periphery. The light receiving section 12b is placed opposite to the light receiving section 12b with the measuring plate 10 in between.

13 is a limit switch for switching the injection secondary layer, and 14 is a limit switch for preventing the injection ram 4 from retreating below the metering distance, each of which is fixed on the base near the holding plate so as to be activated by the upper end of the movable plate 7. It is.

The weighing device having the above structure is attached to the window hole 16 provided in the cylinder 15 of the injection device through the base 1 with the rack 6 and the injection ram 4 parallel to each other, and the transmission plate 5 is attached to the injection ram 4. They are connected and set so that the movable plate 7 moves forward and backward together with the injection ram 4.

Thus, the movable plate 7 connected to the injection ram 4 via the transmission plate 5 moves linearly with the rack 6 every time the injection ram 4 moves, and rotates the pinion 8 meshed with the rack 6.

Since the measuring plate 10 is attached to this pinion 8, the linear motion of the injection ram 4 is converted into rotational movement, and the measuring plate 10
0.

It turns out.

Then, the light from the light projecting section 12 a is intermittently received by the light receiving section 12 b through a large number of slits 11 so that the phototube device 12
When the count reaches a set value, the injection ram 4 is stopped by the action of the electric circuit and the measurement is completed.

The above-mentioned electric circuit may have a structure generally used in injection molding, and the injection ram 4 may be moved forward after metering using a timer as in the past.

As mentioned above, this idea rotates a measuring plate with a large number of slits in accordance with the movement of a screw that moves forward and backward together with an injection ram using a pinion and a rack that engage with each other.
Since the distance of movement of the screw is counted by the phototube device by the rotation and the retraction distance of the screw can be controlled by the set value, there is no need to set the position of the limit switch even if the injection material changes.

In addition, the amount of movement on the circumference of the circular measuring plate is proportional to the radius, and the amount of movement of the screw is calculated by increasing it, so even the slightest movement of the screw can be counted by the radial slits, resulting in an error. is small and allows for precise measurement.

Furthermore, since the measuring plate is rotated by a pinion and a rack, the structure is simple, and it has the advantage of being able to be used by being attached to an injection device of conventional structure.

[Brief explanation of the drawing]

The drawings show one embodiment of the measuring device for an injection molding machine according to this invention. Figure 1 is a front view, Figure 2 is a vertical side view of the measuring plate part 1, and Figure 3 is a view with the measuring device installed. It is a side view of an injection device. 1... Base, 2... Holding plate, 3...
...Guide rod, 4...Injection ram, 5...
...Transmission plate, 6...Rack, 7...
・Movable plate, 8...Pinion, 10...
Measuring plate, 11...Slit, 12...
Phototube device, 12a... Light projecting section, 12b...
... Light receiving section, 13 ... Limit switch for switching secondary injection pressure.

Claims (1)

[Scope of utility model registration request] A base attached to a window hole provided in a cylinder of an injection device, a movable plate having a transmission plate slidably straddling a guide rod horizontally suspended on the base and connected to an injection ram side, and the movable plate A circular measuring device having a rack protruding parallel to the guide rod from the side thereof, a pinion supported on the base side and meshed with the rack, and a number of slits attached concentrically to the pinion along the periphery. A measuring device for an injection molding machine comprising a plate, and a phototube device in which a light emitting part and a light receiving part are placed opposite to each other with the periphery of the measuring plate in between and fixed to the base side.