JPH0242339B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for monitoring the quality of a molded product produced by an injection molding machine, and in particular, a method for monitoring the quality of a molded product by monitoring the resin temperature during the injection process. The present invention relates to an injection process monitoring method for determining.

[Prior art and its drawbacks]

Conventionally, there is a method of checking the amount of cushioning, filling time, measuring time, etc. in an injection molding machine to judge the quality of a molded product. However, these methods can only detect data at only one point in one shot.

There is also a method of continuously monitoring the cavity internal pressure and injection pressure during one shot, but both the mold internal pressure and the injection cylinder pressure depend on the viscosity of the plasticized resin and the surface temperature of the mold in which it is filled. It is affected by both the determined flow resistance, and when fluctuations are detected, it is unclear whether the cause is due to the aforementioned viscosity or the surface temperature of the mold. Therefore, it was not possible to decide which part to correct.

Furthermore, there is a method of continuously monitoring the resin pressure and resin temperature based on the time from the start to the completion of the injection process, but if time is used, the set time will elapse regardless of the molten resin. The molten state of the resin is unknown.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks that existed when determining the quality of a conventional molded product, and provides an injection process monitoring method that can determine the quality of a molded product by monitoring the injection process. The purpose is to

[Key points of the invention]

In order to achieve the above-mentioned purpose, the injection process is divided into a filling process in which molten resin is filled into the mold, and a contraction caused by the cooling and solidification of the molten resin filled in the mold, over the entire injection process in one shot. During the filling process, the resin temperature is continuously sampled at multiple points according to the position of the screw or plunger, and during the pressure holding process, depending on the time from the start of holding pressure to the completion of holding pressure. The temperature of the molten resin in the subsequent molding cycle is continuously detected by the screw or plunger position during the filling process and by the pressure holding time during the pressure holding process, and the corresponding value on the reference temperature curve is determined as a reference temperature curve. Compare the deviation with
This is an injection process monitoring method for an injection molding machine that is characterized by determining the quality of a molded product. In this injection process monitoring method, the curve can also be an average temperature curve of resin temperatures detected multiple times depending on the screw or plunger position during the filling process and based on the pressure holding time during the pressure holding process.

〔Example〕

Next, one embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 11 is an injection molding machine, and resin temperature detection sensors are located at the cylinder head 12, nozzle 13,
and is attached to the mold cavity 14. 1
Reference numeral 5 denotes a changeover switch for switching the sensors 12 to 14. 16 is a position detection device for detecting the position of the screw 17. 18 is an arithmetic comparison device which compares the temperature a detected by one of the sensors 12 to 14 with a preset temperature curve c during molding of a good product as shown in FIG. According to the position s of 17, the preset tolerance value ΔT is determined by the pressure holding time t during the pressure holding process.
It monitors whether or not the molding machine is within the temperature range, and feeds back the results to the heating control unit 19 of the molding machine, and sends signals 20, 21 for checking the quality of the molded product 24, stopping the operation of the molding machine, and warnings. etc. can be emitted. The results can also be output to the CRT 22 or printer 23 as shown in FIG.

[Effect]

With the configuration described above, changes in resin temperature during the injection process can be observed, so changes can be made at the screw or plunger position during filling, and at what time during the pressure holding process. Prove. For example, if a sink mark appears on a molded product, the resin temperature will change during pressure holding, and if there is gas entrainment during measurement in the pre-filling process, the filling process will be filled with resin using adiabatic compressed gas. A rise in temperature can be seen.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an example of displaying continuous resin temperature in the injection process according to the present invention. 11... Injection molding machine, 12... Cylinder head, 13... Nozzle, 14... Mold cavity,
15...Switchover switch, 16...Position detection device,
17...Scrillu, 18...Arithmetic comparison device, 19
... Heating control section, 22 ... CRT, 23 ... Printer.

Claims (1)

[Claims] 1. The injection process in an injection molding machine is divided into a filling process for filling the mold with molten resin and a pressure holding process for compensating for shrinkage due to cooling and solidification of the molten resin filled in the mold. During the dividing filling process, the resin temperature during molding of a good product is continuously sampled at multiple points according to the position of the screw or plunger, and during the pressure holding process, depending on the time from the start of holding pressure to the completion of holding pressure. The temperature of the molten resin in the cycle is continuously detected by the screw or plunger position during the filling process and by the pressure holding time during the pressure holding process, and the deviation from the corresponding value on the reference temperature curve is compared and the deviation is determined. Determine whether the predetermined tolerance value has been exceeded,
A method for monitoring an injection process in an injection molding machine, characterized by determining the quality of a molded product. 2. The injection process monitoring method according to claim 1, wherein the temperature of the molten resin is detected by a temperature sensor attached to a nozzle of an injection molding machine. 3. The injection process monitoring method according to claim 1, wherein the temperature of the molten resin is detected by a temperature sensor attached to a cylinder head of an injection molding machine. 4. The injection process monitoring method according to claim 1, wherein the temperature detection of the molten resin is performed within a mold cavity. 5. The reference temperature curve is an average temperature curve of resin temperatures detected multiple times depending on the position of the screw or plunger during the filling process and based on the pressure holding time during the holding pressure. The injection process monitoring method according to item 4.