JPS63242619A - Injection molding equipment - Google Patents

Abstract

PURPOSE:To improve the durability of molds even when the molds, which are manufactured easily at low cost, are employed, by a method wherein a mold clamping force applied to the parting faces of the molds is controlled to the necessary minimum during injection process or period ranging from the start of injection of molten material in the molds to its end. CONSTITUTION:The molten material 11 in an injection cylinder 10 is injected in the inner space 15 of clamped molds 14 by shifting a screw 12 in the cylinder toward a nozzle 13 side. A detecting means 16 to detect the mold clamping force applied to the parting faces of the molds, and a control part 17, which variably controls the mold clamping force of a mold clamping device 18 during the period ranging from the start of injection of molten material in the inner space to its end on the basis of signals sent from the detecting means are equipped. The control part 17 controls the detected mold clamping force applying to the parting faces of the molds from the start to the end of injection to nearly constant minimum necessary mold clamping force by changing the mold clamping force applying to the mold clamping device 18. As a result, injection molding can be done without applying load, which is beyond the necessary pressure, to the parting faces of the molds, so the durability of the molds is improved, even when the molds are made of material having lower resistance to surface pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding apparatus such as an injection molding machine or a guicasting machine, and particularly relates to controlling the clamping force of a mold during the injection process.

[Conventional technology]

Generally, injection molding equipment is used in the injection process.

The molten material such as resin, aluminum, ceramic, etc. in the injection cylinder is injected into the inner space of the clamped mold by moving the screw or piston in the injection cylinder toward the nozzle side.

However, in conventional injection molding apparatuses, the maximum mold clamping force is generated in the device that requires it during the injection process from the start of injection to the end of injection for injecting the molten material into the inner space of the mold.

[Problem that the invention seeks to solve]

However, with this method, the injection start and end points,
Even when the pressure applied to the internal space of the mold is lower than the peak pressure, the mold clamping device always generates a constant mold clamping force, so that the clamping force is applied to the mold's cutting surface.

Even though only a small mold clamping force is required, the z4-ting surface (contact surface) of the mold, which is the weakest in terms of two-surface pressure, cannot withstand the repeated load because more force than necessary is applied.

For example, in the case of a mold made of an At alloy, the parting surface collapses after a few shots, making it unusable and making it impossible to mold the required number of products.

For this reason, depending on the required quantity of molded products, we select the strength of the mold and use green mold, heat-treated mold, hardened mold, etc. to ensure durability. Since the number of man-hours and price increase almost in proportion to the durability, expensive molds are used in any case.

An object of the present invention is to provide an injection molding apparatus that can improve the durability of the mold even when using a mold that is easy to manufacture and inexpensive.

Another object of the present invention is to provide an injection molding apparatus in which the notting surface of the mold is less likely to collapse.

[Means for solving problems]

According to the present invention, as shown in FIG. 1, the molten material 11 in the injection cylinder 10 is transferred to the mold 14 by moving the screw 12 in the cylinder toward the nozzle 13. In an injection molding apparatus that injects into the inner space 15, a detection means 16 for detecting the mold clamping force applied to the parting surface of the mold, and a detection means 16 for detecting the mold clamping force applied to the parting surface of the mold, and a detection means 16 for detecting the mold clamping force applied to the parting surface of the mold, Mold clamping device 1
and a control section 17 for variably controlling the mold clamping force of No. 8 according to the signal from the detection means.

The mold clamping force applied to the mold clamping device is varied so that the detected mold clamping force applied to the mothering surface of the mold from the start to the end of the injection becomes a necessary minimum, almost constant mold clamping force. An injection molding apparatus is obtained, which is characterized in that:

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In general, in injection molding equipment, if a minimum necessary mold clamping force is applied to the mold during the injection process, which exceeds the product of the area where the molten material is injected and the pressure applied there, the mold will close. Since there is no gap between the parting surfaces, there is no problem in molding. The present invention utilizes this principle.

Referring to FIG. 1, the injection molding apparatus according to one embodiment of the present invention moves the molten material 11 in the heating cylinder 10 to the nozzle 13 by moving the screw 12 in the heating cylinder 10 toward the nozzle 13. From there, it is injected into the inner space 15 of the mold 14 which has been clamped.

In this embodiment, a surface pressure measuring device 16 for detecting the parting surface pressure of the mold 14 is provided as a detection means for detecting the mold clamping force applied to the parting surface of the mold 14. The section 17 consists of a micro-butter.

It is connected to the surface pressure measuring device 16, and the mold clamping force of the mold clamping device 18 at each point in time from the start to the end of injection of the molten material 11 into the inner space 15 can be varied according to the signal from the surface pressure measuring device 16. control. At this time, the control unit 17 controls the mold clamping applied to the parting surface of the mold 14 so that the surface pressure detected by the surface pressure measuring device 16 is substantially equal to the set surface pressure from the start to the end of the injection. Keep the force almost constant. For this purpose, the mold clamping force determined by the control unit 17 is determined by the pressure regulator 1
9 to the mold clamping device 18.

Next, a description will be given of means for providing the control section 17 with information for applying the minimum necessary surface pressure to the /-1'-ting surface of the mold 14 described above.

As mentioned above, during the injection process, if a necessary minimum mold clamping force exceeding the product of the area where the molten material is injected and the pressure applied thereto is applied to the notting surface of the mold 14. , the parting surface of the mold 14 will not open. This embodiment is based on this principle.

An in-mold pressure detection device 20 is installed in the inner space (cavity) 15 of the mold 14, and the control unit 17 calculates and sets the estimated injection area and mold in advance based on the amount of molten material to be injected and the average wall thickness. The product of the mold pressure detected by the internal pressure detection device 20 is calculated. This calculated product is applied to the pressure regulator 19, and the pressure regulator 19 applies a mold clamping force proportional to this calculated product to the mold clamping device 18. For details,
The control unit 17 stores the injection amount and the mold pressure corresponding to the injection amount at each time point from the start to the end of injection of the molten material 11 into the inner space 15, The injection amount is calculated based on the output signal from the digital displacement detector 21 that detects the displacement from the starting position. On the other hand, the control unit 17 determines whether the detected surface pressure from the surface pressure measuring device 16 matches the set surface pressure or not, and if it does not match, the pressure regulator 19 (and injection pressure) is adjusted so that the surface pressure matches the set surface pressure. control.

In this way, injection molding can be performed without applying more than the required pressure to the parting surface of the mold 14, and even if the mold is made of a material with low surface pressure resistance (for example, M alloy), Durability is improved.

Note that an injection pressure detector 22 may be provided in place of the in-mold pressure detection device 20, and the injection pressure detected by the injection pressure detector 22 may be used as the above-mentioned in-mold pressure.

Furthermore, the mold clamping means of a molding apparatus to which this invention can be applied is not limited to a direct pressure type using a hydraulic ram, but may also be a toggle type mold clamping means, by inserting a ram cylinder or the like between the toggle device and the mold. It can function in the same way as the direct pressure type.

〔Effect of the invention〕

As explained above, according to the present invention, during the injection process, the mold clamping force applied to the mold parting surface from the start to the end of injection of the molten material into the mold is the minimum necessary mold clamping force. The mold clamping force applied to the mold clamping device is controlled so that the durability of the mold can be improved even if a mold that is easy to manufacture and inexpensive is used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an injection molding apparatus according to an embodiment of the present invention. 10...Heating cylinder, 11...Melting material, 12.
...Screw, 13...Nozzle, 14...Mold,
15... Inner space, 16... Surface pressure measuring device, 17...
Control unit, 18--mold clamping device, 19--pressure regulator,
20... In-mold pressure detection device, 21... Digital displacement detector, 22... Injection pressure detector.

Claims (1)

[Claims] 1. In an injection molding device that injects molten material in an injection cylinder into the inner space of a clamped mold by moving a screw in the cylinder toward the nozzle side, the molten material is added to the parting surface of the mold. a detection means for detecting a mold clamping force; and a control unit for variably controlling the mold clamping force of a mold clamping device from the start to the end of injection of the molten material into the inner space based on a signal from the detection means. The control unit controls the mold clamping device so that the detected mold clamping force applied to the parting surface of the mold from the start to the end of the injection becomes a necessary minimum, almost constant mold clamping force. An injection molding device characterized by changing the mold clamping force applied.