JP2008188909A - Injection molding machine/method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the dispersion of molding precision and finished product failure attributed to the dispersion of an internal temperature distribution of a molded object during cooling, in injection molding technique. <P>SOLUTION: First, a plurality of temperature sensors 3 is arranged equally around each of a plurality of cavities 4 formed in a mold 1, and the temperature distribution is detected by an external temperature detector 8. Further, in a calculation/control device 9, the temperature width T<SB>2</SB>around the individual cavity 4, is calculated from the temperature detected by the temperature sensor 3, and the timing of opening the mold 1 is controlled through a molding machine-side control device 10 so as to open the mold 1 at the point of time when the temperature width T<SB>2</SB>to the target temperature width T<SB>1</SB>when the molded object is unloaded from the preset cavity 4, is T<SB>1</SB>>T<SB>2</SB>and the relationship between the inter target cavity temperature difference T<SB>3</SB>and the intercavity temperature difference T<SB>4</SB>is T<SB>3</SB>>T<SB>4</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injection molding technique, for example, a technique effective when applied to injection molding of precision parts such as optical parts.

  In general, injection molding includes a process of injecting molten resin into a cavity provided in a mold, holding pressure, then cooling, opening the mold, and taking out the molded product. The time during which pressure is applied and the time during which the resin is cooled are set by a worker to set a certain time that is necessary and sufficient to obtain the shape and accuracy of a target molded product. Among them, the cooling time is a very important condition in terms of quality and cycle time.

  This cooling time is mainly determined by the temperature and physical properties of the resin filled in the mold and the temperature control performance of the mold. The temperature control of this mold is controlled by the temperature-controlled water or oil temperature control medium in the mold. It is done by passing.

  However, the temperature control medium flow path is uniform with respect to the cavity that is the part (sealed space) where the molded product is obtained (sealed space) due to restrictions on the mold structure and workability, and the temperature control medium flow path is secured near the cavity. I can't do it. For this reason, the resin filled in the mold is not uniformly cooled, and a temperature distribution is generated in the molded product. As a result, the shape of the molded product is changed and accuracy is deteriorated.

  It is known that such a temperature distribution in the molded product appears prominently when the cooling time is short, and tends to gradually disappear as the cooling time increases. Therefore, conventionally, the above-mentioned problem is dealt with by taking a long cooling time. However, this increases the molding cycle time, resulting in an increase in molding cost.

  Since the cooling time is constant as described above, when the molding conditions such as the mold temperature vary due to the influence of disturbance or the like during continuous molding, the influence directly appears on the molded product. Therefore, it is expected that the variation in accuracy of the molded product will increase, and the productivity is very poor.

  Among them, for the purpose of grasping the cooling state of the molded product and determining the cooling time based thereon, in Patent Document 1, the temperature in the mold is measured, and the cooling time is set according to the temperature rise of the mold. Proposed to be longer.

  Moreover, in patent document 2, when the temperature output from the temperature sensor embedded in the mold so as to measure the surface temperature of the injection molded product reaches a preset molded product temperature, the mold is opened. A method of controlling the cooling time so as to take out the molded product has been proposed.

However, in both methods of Patent Document 1 and Patent Document 2, since the temperature inside the mold or the surface of the molded product is measured only at one representative point, the cooling state of the entire molded product is completely captured. It is difficult to say that there is a concern that the molded product is not molded with an optimal cooling time. Moreover, it is expected that the value to be set varies depending on the place where the temperature is measured, and there is a possibility that a sufficient effect may not be obtained depending on the place where the temperature is measured.
JP-A-6-254929 Japanese Patent Laid-Open No. 5-192777

An object of the present invention is to reduce variations in molding accuracy and product defects due to variations in temperature distribution in a molded product during cooling in the injection molding technique.
Another object of the present invention is to reduce variations in molding accuracy and product defects caused by variations in temperature distribution in a molded product during cooling without setting a molding cycle time longer than necessary.

  Another object of the present invention is to improve injection molding productivity by shortening molding cycle time and reducing molding accuracy variation and product defects.

A first aspect of the present invention is an injection molding apparatus for injecting a molten resin into a cavity in a mold, holding and cooling, and then opening the mold to obtain a molded product,
A plurality of temperature measuring means disposed around the cavity of the mold;
The temperature range T ₂ of the surrounding from the detected temperature of the cavity by the temperature measuring means calculates, said temperature range T ₂ with respect to the target temperature range T ₁ of the case is taken out from the cavity preset the molded article, Control means for controlling the injection molding apparatus to open the mold for taking out the molded product when T ₁ > T ₂ ;
An injection molding apparatus is provided.

A second aspect of the present invention is a multi-cavity injection in which a molten resin is injected into a plurality of cavities in a mold, and after holding and cooling, the mold is opened to simultaneously mold a plurality of molded products. A molding device,
A plurality of temperature measuring means uniformly arranged around each said cavity;
For each of the cavities, an average value is calculated from the temperatures detected by the plurality of temperature measuring means uniformly arranged around the cavity, and is calculated from the difference between the maximum value and the minimum value among the average values. When the inter-cavity temperature difference T ₄ is in a relationship of T ₃ > T ₄ with respect to the target inter-cavity temperature difference T ₃ when the molded product is taken out from the preset cavity, the molded product is taken out. Control means for controlling the injection molding device to open the mold for
An injection molding apparatus is provided.

According to a third aspect of the present invention, a step of injecting a molten resin into a cavity in a mold and performing holding pressure and / or cooling,
The calculated temperature range T ₂ of the around the cavity from the detected temperature by the plurality of temperature measuring means disposed around the cavity, the temperature range T ₂ is, when taking out the molded article from the cavity to a preset Opening the mold when T ₁ > T ₂ with respect to the target temperature range T ₁ ;
An injection molding method is provided.

According to a fourth aspect of the present invention, a step of injecting a molten resin into each of a plurality of cavities in a mold to perform pressure holding and / or cooling,
For each of the cavities, an average value is calculated from the temperatures detected by temperature measuring means disposed around the cavity, and a maximum value and a minimum value among a plurality of the average values measured from the individual cavities. When the inter-cavity temperature difference T ₄ calculated from the difference between the values becomes T ₄ <T ₃ with respect to the target inter-cavity temperature difference T ₃ when the molded product is taken out from the cavity, Opening the mold,
An injection molding method is provided.

  According to the present invention, for example, by providing a plurality of temperature measuring means around the cavity, the temperature distribution of the entire molded product can be grasped, and the molded product can be molded with the optimal molding cycle from those results. Thus, it is possible to reduce the probability of mixing of molding variations and defective molded products, and to improve productivity.

  In other words, it is possible to understand the temperature distribution in the molded product during cooling and to perform molding with the optimal cooling time considering the entire molded product, and without having to set the molding cycle time longer than necessary. The variation in molding accuracy is reduced, product defects can be reduced, and injection molding productivity is improved.

According to the present invention, in the injection molding technique, it is possible to reduce variations in molding accuracy and product defects caused by variations in temperature distribution in the molded product during cooling.
Moreover, it is possible to reduce variations in molding accuracy and product defects due to variations in temperature distribution in the molded product during cooling without setting a molding cycle time longer than necessary.

  Moreover, the productivity of injection molding can be improved by shortening the molding cycle time and reducing variations in molding accuracy and product defects.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Embodiment 1]
(Constitution)
Embodiment 1 of the present invention will be described below with reference to FIGS. 1A and 1B.

  FIG. 1A is an explanatory diagram for explaining an outline of an injection molding apparatus that performs an injection molding method according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. It is.

The injection molding apparatus 100 of the present embodiment includes a mold 1 (molding die), a temperature detector 8, a calculation / control device 9 (control means), and a molding machine side control device 10.
As shown in FIGS. 1A and 1B, the mold 1 includes a fixed mold 1 a and a movable mold 1 b, and a plurality of cavities 4 are formed in the mold 1. That is, the mold 1 of the present embodiment has a so-called multi-cavity configuration in which a plurality of molded products 11 are simultaneously molded from a plurality of cavities 4 by one injection molding.

  The fixed side mold 1a and the movable side mold 1b are provided with protruding inserts 12 in the opposing direction, and the opposing end faces are provided with a molding surface 12a and a molding surface 12b. Then, in a state where the fixed side mold 1a and the movable side mold 1b are in close contact, the molding surface 12a and the molding surface 12b form a cavity 4 that is a sealed space.

  On the fixed-side mold 1a side, a sprue 5 that opens to the center of the arrangement area of the plurality of cavities 4 and a plurality of radial runners 6 that communicate from the sprues 5 to the individual cavities 4 are provided.

  The resin (not shown) injected into the sprue 5 from the outside is filled into the individual cavities 4 via the runners 6 and the gates 7 which are the diameter-reduced portions provided at the connection portions between the runners 6 and the respective cavities 4. Then, it is molded into a molded product 11 having an outer shape to which the shapes of the molding surface 12a and the molding surface 12b are transferred.

  The mold 1 is provided with a temperature control medium flow path 2 around a plurality of cavities 4, and a heat medium having a desired temperature is circulated through the temperature control medium flow path 2 from the outside. The temperature of the cavity of the mold 1 is controlled.

  In the case of the present embodiment, a plurality of temperature sensors 3 (temperature measurement means) are embedded around each cavity 4. The temperature sensor 3 includes a detection unit 3 a having a function of detecting a temperature, and a conductive wire 3 b for transmitting information of a detection result to an external temperature detector 8.

  In this case, the detection unit 3a of the temperature sensor 3 is provided with, for example, three points at the same distance from the wall so as to surround each of the four cavities 4, for a total of 12 points. 1b and the fixed side mold 1a.

  In the first embodiment, for example, the detection unit 3a of the temperature sensor 3 is placed at a uniform arrangement angle around the cavity 4 (1.5 mm from the wall of the cavity and 2 mm from the parting surface of the mold). In this case, they are uniformly arranged at 120 °.

  Moreover, the output from the detection part 3a of this temperature sensor 3 is sent to the temperature detector 8 via the conducting wire 3b, and the temperature detector 8 converts the result of converting the signal from the temperature sensor 3 into a temperature value as temperature information 3c. To the calculation / control device 9 as follows. In the calculation / control apparatus 9, the mold opening / closing signal 9a output based on the temperature information 3c is sent to the molding machine side control apparatus 10, and the injection molding apparatus 100 determines the mold opening / closing operation command depending on the mold opening / closing signal 9a. By outputting 10a, the movable side mold 1b is opened and closed with respect to the fixed side mold 1a of the mold 1.

  In the present embodiment, the detection unit 3a of the temperature sensor 3 is disposed at a position 1.5 mm from the wall surface of each cavity 4 and 2 mm from the parting surface of the mold 1 as an example. This distance should be close to the wall surface of the cavity 4.

(Function)
Hereinafter, an example of the procedure of the molding process in the injection molding apparatus 100 of the present embodiment will be described with reference to FIGS. 1A, 1B, 2, and 3.

FIG. 2 is a block diagram for explaining the function of the injection molding apparatus to which the present embodiment is applied.
Each temperature sensor 3 transmits the measured value of the temperature of each cavity 4 detected at the installation point of the detection unit 3a to the calculation / control apparatus 9 as temperature information 3c via the lead 3b.

The calculation / control device 9 includes a target temperature width T ₁ , a target inter-cavity temperature difference T ₃ , a cooling upper limit time t _max , an allowable continuous failure upper limit number N _max, and individual temperatures obtained from the temperature sensors 3. Based on the temperature information 3c that is a measurement result of the temperature of the cavity 4, a mold opening / closing signal 9a is output to the molding machine side control device 10 by a determination process as described later.

Based on the mold opening / closing signal 9a, the molding machine side controller 10 outputs a mold opening / closing operation command 10a to the mold 1 to cause the movable mold 1b to open / close with respect to the fixed mold 1a.
FIG. 3 is a flowchart showing an example of the operation of the injection molding apparatus 100 including the operation in the calculation / control apparatus 9.

First, the number of consecutive defects n is initialized to 0 (step 201).
Next, injection molding is started. That is, the resin melted by heating by a plasticizing device (not shown) of an injection molding machine is press-fitted into the sprue 5 in the mold, passes through the runner 6 and the gate 7, and enters the cavity 4 which is a part for obtaining a molded product. It is injected and filled (step 202).

  Each temperature sensor 3 embedded around the cavity 4 detects in real time the temperature change in the vicinity of the cavity 4 when the resin is gradually cooled after injection of the resin, and sends the result to the calculation / control device 9 (step 203). ).

In the calculation / control apparatus 9, as shown in FIG. 3, first, from the input output temperature (temperature information 3c) of each temperature sensor 3, the temperature width T ₂ around each cavity (step 204) and the inter-cavity temperature difference T ₄ (Step 206, Step 207) is calculated.

Here, the temperature width T ₂ around the cavity 4 in step 204 is, for example, the difference between the maximum value and the minimum value among the output values of the temperature sensor 3 arranged uniformly around one cavity 4. It refers to something taken.

The temperature difference T ₄ between the cavities in step 207 is, for example, an average of the outputs of the temperature sensors 3 arranged around each cavity 4 in step 206 as an average temperature of each cavity. It indicates the difference between the maximum and minimum values among the average temperatures of 4.

Next, these calculated values are compared with the target temperature width T ₁ (step 205) and the target inter-cavity temperature difference T ₃ (step 208) that have been input to the calculation / control device 9 in advance. It is determined whether ₁ > T ₂ and T ₃ > T ₄ are satisfied (step 209).

  Then, before the cooling time t exceeds the cooling upper limit time tmax (step 213), a mold opening / closing signal 9a is sent to the molding machine side control device 10 so as to open the mold when the relationship becomes such a relationship (step 210). ), The molding machine side control device 10 opens the mold, takes out the molded product as a non-defective product (step 211), returns to step 201, initializes the number of consecutive defects n to 0, and then proceeds to the next molding.

On the other hand, if the condition in step 209 is not satisfied, the cooling upper limit time t _max is input to the calculation / control device 9 in advance (step 212), and the cooling time t after resin injection is t <t _max . If T ₁ > T ₂ and T ₃ > T ₄ are not satisfied for each cavity (step 213), the number of consecutive defects n is incremented by 1 (step 214), and the molded product is determined to be defective ( Step 215), taking out the molded product which is determined to be non-defective (step 218), returning to step 202 and starting the next molding process.

Also, before the step 218, if the number of consecutive defects n continues for the upper limit number N _max (step 216) of the allowable consecutive defects that is a predetermined number (step 216), an alarm is issued and injection molding is performed. Stop (step 219).

In FIG. 3 described above, determination is made based on both conditions of the temperature width T ₂ around each cavity 4 and the inter-cavity temperature difference T ₄ between the plurality of cavities 4. one of only two or cavity between the temperature difference T ₄ the determination may be performed using.

For example, in the case of so-called single-piece molding in which a single cavity 4 is provided in the mold 1, the determination is based only on the temperature width T ₂ around the single cavity 4.
Further, as in the second embodiment, when a plurality of cavities 4 are provided in the mold 1, both the temperature width T ₂ and the inter-cavity temperature difference T ₄ are used as described above. The determination using only one of them is also possible.

Here, the target temperature width T ₁ and the target inter-cavity temperature difference T ₃ are obtained by preliminary experiments or set by empirical values or simulations so as to obtain the required accuracy of the molded product. As a general guideline, if the target temperature width T ₁ is set small, the accuracy of the molded product is improved, and in particular, warpage of the molded product and dimensional asymmetry can be eliminated. Further, the smaller the target inter-cavity temperature difference T ₃ , the smaller the accuracy variation of the molded product between the cavities, and the more stable production becomes possible.

  Hereinafter, this mechanism will be described with reference to FIG. The resin filled in the mold 1 is gradually cooled by the temperature adjustment function by the heat medium flowing through the temperature control medium flow path 2 of the mold 1. The temperature control of the mold 1 is performed by passing a temperature-controlled water or oil cooling medium through the mold as described above. The temperature control medium flow path 2 has the structure of the mold 1 and the temperature control. Due to processing restrictions on the medium flow path 2, the molded product, that is, the cavities 4 cannot always be arranged uniformly. For this reason, the resin cannot be uniformly cooled, and a temperature distribution is generated in the molded product 11, and due to this, a distribution is also generated in the thermal shrinkage rate in the molded product 11.

  For example, in the arrangement of the plurality of cavities 4 as shown in FIG. 4, in each of the three cavities 4 on the right side close to the temperature control medium flow path 2 of the U-shaped path, On the opposite side far from the temperature control medium flow path 2, the cooling, that is, the shrinkage is slow.

Further, the cooling (shrinkage) of the entire left cavity 1 farthest from the temperature control medium flow path 2 is slower than that of the other three cavities 4.
Such a temperature distribution in the molded product 11 appears prominently when the cooling time is short, and tends to be eliminated by taking a long cooling time, but the cooling is insufficient, that is, in the molded product 11. When the mold 1 is opened and the molded product 11 is taken out when the variation in temperature distribution is large, the molded product 11 is deformed according to the temperature distribution, and warpage and dimensional asymmetry occur, resulting in the required accuracy. Can not be satisfied.

This also applies to the target inter-cavity temperature difference T ₃ between the cavities 4. The temperature control medium flow path 2 cannot be similarly arranged with respect to each cavity 4 as shown in FIGS. 1A and 1B. Therefore, most cavities 4 are not cooled in the same way, and the cooling state varies between cavities. As a result, the accuracy of the molded product varies depending on the position of each cavity 4.

FIG. 5 shows the relationship between the result of actually measuring the temperature width T ₂ around the cavity and the accuracy of the molded product (optical element). The PV value in FIG. 5 is a value indicating the difference between the lens design shape and the actually measured shape of the molded lens, and the asymmetry (As) indicates the asymmetry of the shape in two orthogonal directions of the lens. Value.

From FIG. 5, it can be said that the temperature distribution in the molded product has a great influence on the accuracy of the molded product because the accuracy of the molded product is worsened as the temperature width T ₂ that is the temperature difference around the cavity is larger.

In the present embodiment, as an example, molding was performed with the target temperature width T _{1 set} to 0.35 [° C.] and the target inter-cavity temperature difference T _{3 set} to 0.4 [° C.]. At that time, the temperature sampling interval was 0.1 [s] (seconds), and T ₂ and T ₄ at each time were determined from the moving average of the previous 10 points. As a result of molding under such conditions, it was possible to stably obtain a molded product that satisfies the required accuracy.

In the present embodiment, as an example, molding was performed with the target temperature width T _{1 set} to 0.35 [° C.] and the target inter-cavity temperature difference T _{3 set} to 0.4 [° C.]. Depending on the size of the molded product 11 and the required accuracy, both T ₁ and T ₂ are approximately in the range of 0.1 [° C.] to 0.5 [° C.] in the case of optical lenses, and in the case of general structural parts When T ₁ is set in the range of 0.1 [° C.] to 1 [° C.] and T ₂ is set in the range of 0.1 [° C.] to 1 [° C.], the shape accuracy of the molded article 11 can be sufficiently secured. If the temperature is lower than this range, the general resolution of the temperature sensor 3 is exceeded. Therefore, setting a temperature lower than 0.1 ° C. is not very realistic.

  The temperature sampling interval is preferably set in the range of the minimum response speed of the temperature sensor 3 to be used to 0.1 [s]. If a sampling interval larger than this is set, it becomes difficult to control the molding cycle in seconds, which is not practical. Regarding the number of points for calculating the above moving average, it is desirable to set it so that it is 10 points or more and the calculation width of the moving average (sampling interval × number of moving average calculation points) is 1 [s] or less. . When the number is less than 10, the influence of noise during sampling increases. Moreover, if a value is set such that the temperature width of the moving average exceeds 1 [s], it becomes difficult to sufficiently capture the temperature change during cooling.

  As described above, according to the first embodiment, it is possible to reduce the accuracy deterioration of the molded article 11 due to the temperature difference around the cavity 4 and to perform molding at an optimum cycle time to prevent such accuracy deterioration. It becomes possible. That is, in order to wait until the whole is uniformly cooled below a predetermined temperature, it is not necessary to set a uniformly long cycle time.

In addition, since molding is performed with an optimum cycle time for each molding, the influence of disturbance and the like can be reduced, and stable production with small quality variation during continuous molding is possible.
Furthermore, it is possible to reduce the probability that defective products with molding defects will be mixed in the molded product by judging the quality of the molded product based on the measured temperature range and distinguishing the good product from the defective product. become.
[Embodiment 2]
(Constitution)
A second embodiment of the present invention will be described below with reference to FIGS. 6A, 6B, and 7. FIG. 6A is a schematic diagram of a configuration example of the injection molding apparatus 100 according to the second embodiment, and FIG. 6B is a cross-sectional view taken along line BB in FIG. 6A.

In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
6A and 6B, the molded product 11a has a shape with a large thickness deviation (ratio between the thick portion 11b and the thin portion 11c). Similarly to the first embodiment, the temperature sensor 3 is arranged uniformly at a location 1.5 mm from the wall surface of the cavity and 2 mm deep from the parting surface of the mold, In addition, it is arranged at a position of 1.5 mm from the wall surface of the cavity 4.

(Function)
The molding method and process are basically the same as those in the first embodiment, but the molded product 11a in the second embodiment has a large unevenness, so that the periphery of the molded product as in the first embodiment is cooled. Not only the state but also the cooling state of the molded product 11a in the thickness direction is important. As shown in FIG. 7, when the molded product 11a is taken out with a large temperature difference between the thick wall portion 11b and the thin wall portion 11c, the shrinkage rate of the molded product 11a is different due to the temperature difference and the thickness difference, and the accuracy is deteriorated. To do.

  Therefore, in the second embodiment, in order to grasp the temperature state of the thick portion 11b, in addition to the periphery of the molded product 11a, the projecting insert 12 constituting the molding surface 12a and the molding surface 12b of the cavity 4 is provided. The temperature sensor 3 is also arranged.

Then, the temperature width T ₂ around each cavity and the temperature difference T ₄ between the cavities are calculated from the output values of the plurality of temperature sensors 3 including the temperature sensor 3 arranged in the protruding insert 12 as in the first embodiment. Then, with respect to the target temperature width T ₁ and the target inter-cavity temperature difference T ₃ , it is determined whether T ₁ > T ₂ and T ₃ > T ₄ in each cavity 4a.

When such a relationship is reached, a signal is sent to the molding machine side control device 10 to open the mold, and the molding machine side control device 10 opens the mold, takes the molded product as a non-defective product, and proceeds to the next molding.
As a guideline for setting the target temperature width T ₁ and the target inter-cavity temperature difference T ₃ , the smaller the value, the better the accuracy of the molded product, and the larger the value, the same as in the first embodiment. The accuracy of the molded product is poor.

In the second embodiment, as an example, molding was performed with the target temperature width T _{1 set} to 0.5 [° C.] and the target inter-cavity temperature difference T _{3 set} to 0.4 [° C.]. At that time, the temperature sampling interval was 0.1 [s], and the temperature width T ₂ and inter-cavity temperature difference T ₄ at each time were determined from the moving average of the previous 10 points. As a result of molding under such conditions, it was possible to stably obtain a molded product 11a that satisfies the required accuracy.

(effect)
According to the second embodiment, in addition to the periphery of the cavity 4, the temperature sensor 3 is also disposed on the projecting insert 12 that forms the molding surface 12 a and the molding surface 12 b of the cavity 4. The molded product 11a having a large unevenness, which is a dimensional difference of the portion 11c, can be molded with an optimum cycle time to satisfy the required accuracy, and the molded product 11a can be stably produced.

  As described above, according to each of the above-described embodiments of the present invention, in the injection molding technique, it is possible to reduce variations in molding accuracy and product defects due to variations in temperature distribution in the molded product during cooling. it can.

Moreover, it is possible to reduce variations in molding accuracy and product defects due to variations in temperature distribution in the molded product during cooling without setting a molding cycle time longer than necessary.
Moreover, the productivity of injection molding can be improved by shortening the molding cycle time and reducing variations in molding accuracy and product defects.

  Needless to say, the present invention is not limited to the configuration exemplified in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is explanatory drawing for demonstrating the outline | summary of the injection molding apparatus to which this invention is applied. It is sectional drawing of the part of the line AA in FIG. 1A. It is a block diagram for demonstrating the function of the injection molding apparatus to which Embodiment 1 of this invention is applied. It is a flowchart which shows an example of an effect | action of the injection molding apparatus to which Embodiment 1 of this invention is applied. It is explanatory drawing which shows an example of an effect | action of the injection molding apparatus to which Embodiment 1 of this invention is applied. It is a diagram which shows an example of an effect | action of the injection molding apparatus to which Embodiment 1 of this invention is applied. It is explanatory drawing of the structural example of the injection molding apparatus in Embodiment 2 of this invention. It is sectional drawing of the part of line BB in FIG. 6A. It is sectional drawing explaining the effect | action of the injection molding apparatus in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 1a Fixed side mold 1b Movable side mold 2 Temperature control medium flow path 3 Temperature sensor 3a Detection part 3b Conductor 3c Temperature information 4 Cavity 4a Cavity 5 Sprue 6 Runner 7 Gate 8 Temperature detector 9 Calculation / control device 9a Mold opening / closing signal 10 Molding machine side control device 10a Mold opening / closing operation command 11 Molded product 11a Molded product 11b Thick portion 11c Thin portion 12 Projection insert 12a Molding surface 12b Molding surface 100 Injection molding device T ₁ Target temperature range T ₂ Temperature range T ₃ Temperature difference between target cavities T ₄ Temperature difference between cavities n Maximum number of continuous defects N _max Maximum allowable continuous defects t Cooling time t _max Maximum cooling time

Claims (14)

An injection molding apparatus for injecting molten resin into a cavity in a mold, holding and cooling, and then opening the mold to obtain a molded product,
A plurality of temperature measuring means disposed around the cavity of the mold;
The temperature range T ₂ of the surrounding from the detected temperature of the cavity by the temperature measuring means calculates, said temperature range T ₂ with respect to the target temperature range T ₁ of the case is taken out from the cavity preset the molded article, Control means for controlling the injection molding apparatus to open the mold for taking out the molded product when T ₁ > T ₂ ;
An injection molding apparatus comprising: The injection molding apparatus according to claim 1, wherein
An injection molding apparatus, wherein two or more temperature measuring means are uniformly provided around the cavity at the same distance from the wall surface of the single cavity. The injection molding apparatus according to claim 1, wherein
Injection wherein the molded product is determined to be defective when the temperature range T ₂ and the target temperature range T ₁ do not satisfy the relationship of T ₁ > T ₂ during a preset cooling upper limit time t _max Molding equipment. A multi-piece injection molding apparatus that injects molten resin into a plurality of cavities in a mold, holds and cools, and then opens the mold to simultaneously mold a plurality of molded articles,
A plurality of temperature measuring means uniformly arranged around each said cavity;
For each of the cavities, an average value is calculated from the temperatures detected by the plurality of temperature measuring means uniformly arranged around the cavity, and is calculated from the difference between the maximum value and the minimum value among the average values. When the inter-cavity temperature difference T ₄ is in a relationship of T ₃ > T ₄ with respect to the target inter-cavity temperature difference T ₃ when the molded product is taken out from the preset cavity, the molded product is taken out. Control means for controlling the injection molding device to open the mold for
An injection molding apparatus comprising: The injection molding apparatus according to claim 4, wherein
The control means calculates a temperature width T ₂ around each of the cavities from the temperature detected by the temperature measuring means, and with respect to a target temperature width T ₁ when taking out the molded product from the preset cavities. The mold is opened when the temperature width T ₂ satisfies T ₁ > T ₂ and the relationship between the target inter-cavity temperature difference T ₃ and the inter-cavity temperature difference T ₄ satisfies T ₃ > T _4. The injection molding apparatus is controlled as described above. The injection molding apparatus according to claim 4, wherein
An injection molding apparatus characterized in that, for each of the plurality of cavities, two or more temperature measuring means are uniformly provided around each of the cavities at the same distance from the wall surface of each of the cavities. The injection molding apparatus according to claim 4, wherein
Determining that the molded product is defective when the inter-cavity temperature difference T ₄ and the target inter-cavity temperature difference T ₃ do not satisfy the relationship of T ₃ > T ₄ during a preset cooling upper limit time t _max. Characteristic injection molding device. The injection molding device according to claim 3 or claim 7,
An injection molding apparatus characterized in that the control means takes out the molded product determined to be defective from the molded product determined to be non-defective. The injection molding apparatus according to claim 3, 7 or 8,
An injection molding apparatus according to claim 1, wherein the control means stops molding when a predetermined number of molding defects continue. Injecting molten resin into the cavity in the mold and holding and / or cooling;
The calculated temperature range T ₂ of the around the cavity from the detected temperature by the plurality of temperature measuring means disposed around the cavity, the temperature range T ₂ is, when taking out the molded article from the cavity to a preset Opening the mold when T ₁ > T ₂ with respect to the target temperature range T ₁ ;
An injection molding method comprising: Injecting molten resin into each of a plurality of cavities in the mold, and performing pressure holding and / or cooling;
For each of the cavities, an average value is calculated from the temperatures detected by temperature measuring means disposed around the cavity, and a maximum value and a minimum value among a plurality of the average values measured from the individual cavities. When the inter-cavity temperature difference T ₄ calculated from the difference between the values becomes T ₄ <T ₃ with respect to the target inter-cavity temperature difference T ₃ when the molded product is taken out from the cavity, Opening the mold,
An injection molding method comprising: The injection molding method according to claim 11, wherein
In the step of opening the mold,
The temperature The temperature range T ₂ of the around individual of the cavity from the sensed temperature calculated by measuring means, the temperature range T ₂ with respect to the target temperature range T ₁ of the case from the cavity previously set taking the molded article However, the mold is opened when T ₁ > T ₂ and the relationship between the target inter-cavity temperature difference T ₃ and the inter-cavity temperature difference T ₄ satisfies T ₃ > T _4. Injection molding method. The injection molding method according to claim 10, wherein
An injection molding method, wherein two or more temperature measuring means are uniformly provided around the cavity at a fixed distance from the wall surface of the single cavity. The injection molding method according to claim 11, wherein
An injection molding method characterized in that, for each of the plurality of cavities, two or more temperature measuring means are uniformly provided around each of the cavities at a fixed distance from each of the cavity wall surfaces.