JP2002355873A - Method for controlling resin temperature and its injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop an injection molding machine by which mass production of an ultra-precise product such as a DVD disk can be performed not only in one-cavity mold but also in multi-cavity mold. SOLUTION: The injection molding machine is characterized by having a plurality of heaters (91), (92), (93)... arranged on the surroundings of a resin flow hole (201) connected with a mold cavity (5), temperature sensors (41), (42), (43)... for heater parts arranged so as to coincide with the heaters (91), (92), (93)... and a resin temperature sensor (3) arranged among the heaters (91), (92), (93)... and closely arranged to the resin flow hole (201).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin temperature control method for controlling the temperature of a resin filled in a mold cavity, and an injection molding machine therefor.

[0002]

2. Description of the Related Art In injection molding for mass production of ultra-precision products such as DVD disks, it is very important to control the amount of resin filled in a mold cavity. This is because if the amount of the filled resin varies, the resulting molded product also varies, resulting in a fatal defect of the product.

[0003] One of the conditions for determining the amount of resin to be filled into the mold cavity is the temperature of the molten resin. That is, if there is a variation in the temperature of the resin immediately before filling in the mold cavity, the viscosity state of the filling resin also slightly differs, and as a result, the filling situation in each mold cavity also slightly differs. This may cause variations in the filling amount. In order to strictly control the amount of the filled resin, it is necessary to control the temperature of the filled resin to be constant. This point is the same even in the case of multi-cavity molding in which two or more products are molded at a time with one mold, and it is necessary to control the temperature of the resin to be filled in each mold cavity so as to be all the same. is there.

FIG. 5 shows a case where a single piece is formed. (65) (66) is wound and the temperature sensor is located at the same position as the heaters (64), (65) and (66).
(67) (68) (69) is arranged, and the temperature of the resin (60) is controlled by controlling the heaters (64) (65) (66) with the temperature sensors (67) (68) (69). I tried to keep it constant. However, since the temperature sensors (67), (68), and (69) are affected by heat from the heaters (64), (65), and (66), the heater unit temperature sensors (67), (68), and (69)
Is slightly different from the actual temperature of the resin actually filled in the mold cavity (61) from the gate (62). This was considered to be the cause of the temperature variation.

[0005] For these reasons, the actual temperature of the resin (60) filled in the mold cavity (61) could not be accurately measured. 61) It is not possible to maintain a constant amount of resin to be filled, and as a result, it is very difficult to produce a uniform molded product when performing injection molding for mass production of ultra-precision products such as DVD disks. Met.

In particular, in an injection molding machine equipped with a multi-cavity mold having a plurality of cavities in one mold, even if the same mold is used, temperature conditions are slightly different between the upper, lower, left and right sides of the mold. In addition to this, if the temperature of the resin to be filled into the mold cavity is different as described above, the amount of resin to be filled is naturally different. As a result, molding conditions are slightly different for each mold cavity, and each mold is different. Product variability between cavities was unavoidable.

[0007]

The problem to be solved by the present invention is as follows.
An object of the present invention is to develop an injection molding machine capable of mass-producing ultra-precision products such as DVD discs, not only in the case of one-piece but also in the case of many-piece.

[0008]

According to a first aspect of the present invention, there is provided an injection molding machine (A) having a plurality of resin injection holes (201) connected to a mold cavity (5). Heaters (91) (92) (93)
.., and heater unit temperature sensors (41), (42), (43), etc. arranged in correspondence with the heaters (91), (92), (93),.
(92), (93)... And a resin temperature sensor (3) disposed between and adjacent to the resin flow hole (201) ".

According to this, the resin temperature is controlled by the heaters (91) and (92).
Since the temperature is measured by the resin temperature sensor (3) which is disposed between and is close to the resin flow hole (201) and has little heat influence by the heaters (91) and (92), the resin flow is measured. Flow hole (20
The temperature very close to the actual temperature of the resin passing through 1) can be detected. Therefore, if the heaters (91) and (92) are controlled such that the output value of the resin temperature sensor (3) matches the resin set temperature based on the resin temperature sensor (3), the resin will naturally be at the set temperature. Injection filling is performed without variation in the filling amount.

Claim 2 relates to the case of multi-cavity (A2) in the injection molding machine (A).
a) One mold (1a) (1b) provided with (5b), and a resin flow hole (201a) connected to the mold cavities (5a) (5b).
(201b) ・ ・ ・ a plurality of heaters (91a) to (93)
b) ... and the heater temperature sensors (41a) to (43b) ... which are arranged in accordance with the heaters (91a) to (93b) ... and the heater (91
a) to (93b) ・ ・ ・ disposed between the resin flow holes (201a) (201b)
, And resin temperature sensors (3a), (3b),.

In this case, in addition to the above-described operation, an especially effective operation can be obtained in the case of the following multi-cavity production. As described in the conventional example, in case of multi-cavity, the same one mold (1a) (1b)
However, there is slight temperature unevenness in each of the upper, lower, left and right blocks. Each mold cavity (5a) having such subtle temperature unevenness
(5b) If the temperature of the resin to be filled is substantially the same, it is possible to reduce the factors that cause uneven filling.

That is, it is only necessary to control the resin temperature of the resin passing through the resin flow holes (201a) (201b)... By the respective resin flow holes (3a) (3b). It means that.

A third aspect of the present invention relates to a plurality of heaters (91), (92), (93),... Disposed around a resin flow hole (201) connected to the mold cavity (5). , Heater unit temperature sensors (41), (42), (43)
An injection molding machine having a resin temperature sensor (3) disposed between the heaters (91), (92), (93) ... and disposed in close proximity to the resin passage hole (201) ( A1) The resin temperature control method according to (1), wherein the heaters (91) and (9) are set so that the output value of the resin temperature sensor (3) indicates a value that matches the set temperature of the resin passing through the resin passage hole (201).
2) (93) ... ”is controlled.

According to this, the resin temperature sensor (3) which can sense a temperature close to the actual resin temperature without being affected by the heat of the heaters (91) and (92) passes through the resin passage hole (201). The surrounding heaters (91), (92), (93) ... are controlled so that the temperature of the resin to be formed matches the set temperature, so that the mold cavity (5)
The temperature of the resin to be charged into the resin is very close to the set temperature, and the resin is charged without variation. As a result, there is no variation between products, and mass production is possible even for ultra-precision products such as DVD disks.

Claim 4 relates to the case of multi-cavity, wherein one mold (1a) (1b) provided with a plurality of mold cavities (5a) (5b). A plurality of heaters (91a) to (93b) arranged around the resin flow holes (201a) (201b) ... to be connected to the mold cavities (5a) (5b) ... And the heater (91a)
~ (93b) ... heater temperature sensor (4
1a) to (43b) ... and the heaters (91a) to (93b) ... and disposed close to the resin flow holes (201a) (201b) ... An injection molding machine (A) having a resin temperature sensor (3a) (3b)
The temperature control method of 2), wherein each resin temperature sensor (3a) (3b)
.. Correspond to the set temperature of the resin (25a) (25b)... Passing through the resin flow holes (201a) (201b). ) To (93b)...

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment (A1) of a mold mechanism of an injection molding machine (A) according to the present invention is shown in FIGS. 1 and 2, and a second embodiment (A2) is shown in FIGS. explain. The first embodiment (A1) is an example of “one-piece” in which one mold cavity (5) is formed in a pair of male and female molds (1a) and (1b). (A2) is the case of "2 pieces", one mold (1a)
This is an example in which two mold cavities (5a) and (5b) are formed in (1b). Of course, two or more mold cavities (5a) (5b) ...
May be considered, but the case of “two-cavity” will be described as a representative here. Also, "1
Due to the relationship between the sign of "individual" and the case of two-in, it is necessary to assign the same number to the members at the same site, and to distinguish between left and right or upper and lower hot runners in case of two-in. In some cases, a lowercase letter of the alphabet is appended to the number as a branch number, such as (.a) (. B) (. C).

First, a first embodiment (A1) will be described.
FIG. 1 is a cross section of a single-piece mold mechanism of the injection molding machine (A), in which a fixed mold mounting board (2a) and a movable mold mounting board (2b) are installed facing each other. , Fixed die (1a) on fixed die mounting board (2a)
However, the movable mold (1B) is disposed on the movable mold mounting plate (2B) so as to face each other.

A core part constituting a part of the mold cavity (5) is formed on the parting surface of the fixed mold (1). Further, a concave portion corresponding to the core portion and constituting a portion on the opposite side of the mold cavity (5) is formed on the parting surface of the movable mold (1), and the core portion is formed in the concave portion when the mold is closed. Fit and form the mold cavity (5). Also, a tie bar is provided between the fixed mold mounting plate (2a) and the tailstock (7).
(8) is provided, and the movable mold mounting plate (2) is slidably provided.

A gate cut / eject servomotor (11) is provided on the movable die mounting plate (2), and a drive pulley (12) mounted on its rotary drive shaft.
And a driven pulley (13) rotatably held via a bearing on a movable mold mounting plate (2b) via a transmission belt (14). The driven pulley (13) is
The operation nut (15) is provided with an operation screw portion screwed to the rear half of the gate cut pin (16) so as to be able to advance and retreat. Each of the servo motors (11) is provided with a pulse generator.

Further, a mold clamping mechanism comprising, for example, a toggle mechanism (22) is disposed between the movable mold mounting plate (2) and the tail stock (7), and the mold clamping mechanism is operated. With this, a mold operation such as mold opening, mold closing or mold clamping can be performed. There are various types of mold clamping mechanisms, such as a direct-acting type, in addition to the above-mentioned toggle type, and the type is not limited. Here, the toggle type is a representative example.

On the other hand, an injection cylinder (17) is provided at the back of the fixed mold mounting plate (2), and the injection cylinder (17) is provided.
A nozzle (18) formed at the tip of the nozzle matches a spool bush (19) serving as an entrance from which the resin (25) is injected, and the spool bush (19) is a hot runner (20).
Connected to Hot runner (20) is mold cavity
It is connected to the gate (10) of (5) so as to be continuous.
(Here, three) heaters (91), (92), (93),... Are wound at predetermined intervals. The number of heaters (91) (92) (93) is not particularly limited, but is preferably at least two or more in order to accurately control the temperature of the resin (25) immediately before the gate (10). Also, the resin filled in the mold cavity (5)
In order to more accurately control the temperature of (25), it is preferable that the most advanced heater (91) is disposed immediately before the gate (10).

Each of the heaters (91), (92), (93),... Is provided with one heater temperature sensor (41), (42), (43).
The hot runner (20) has a resin flow hole
(201), it is possible to measure a temperature close to the temperature of the resin (25) passing through the hot runner (20). Further, the resin temperature sensor (3) is located at an intermediate position between the heater (91) wound closest to the gate (10) and the heater (92) wound second from the gate (10). ) Is provided so as not to be affected by the heater (9).

The injection molding machine (A) is provided with a control section (24) for controlling the entire system. One of the functions of the control section (24) is that of the heater temperature sensors (41), (42), (43). ) And signals from the resin temperature sensor (3) to change the set temperatures of the heaters (91), (92), (93),.

Next, the operation of the first embodiment (A1) of the present invention will be described. First, the movable mold (1 b) in the mold open state is moved to the fixed mold (1 b) side, and the parting surface of the movable mold (1 b) is moved to the parting surface of the fixed mold (1 b). Stop at the point just before touching. Subsequently, the resin (25) is filled into each mold cavity (5) from the nozzle (18) of the injection cylinder, and the resin (25) injected from the injection cylinder (17) is filled with the spool bush (19). ), Through the resin flow hole (201) in the hot runner (20), and the gate (10) of the mold cavity (5).
It is led to. (Of course, without using hot runner (20),
When injection-filling is performed directly from the nozzle (18) of the injection cylinder (17), the passage in the nozzle (18) becomes the resin flow hole (201). )

Immediately before the gate (10), the hot runner (2
0) Heaters (91) (92) at three locations [or nozzle (18)]
(93) is wound around the heater temperature sensor (41) (3) (4
2) The temperature is controlled by (43) to maintain the temperature of the resin (25) at a predetermined temperature within an extremely narrow allowable range. That is, resin flow holes
The resin (25) measured and heated to a certain temperature is sent into (201). This resin (25) is heated by a heater (91) (92) (93) so that it is kept near the set temperature.
(41) (42) Controlled by (43), but affected by heaters (91) (92) (93) as described in the conventional example, and does not strictly indicate the temperature of resin (25) .

On the other hand, a resin temperature sensor (3) disposed between the heater (91) closest to the gate and the next heater (92).
Are not affected by the heaters (91) and (92) and are actually
The temperature of the resin (25) flowing in (201) can be measured. Therefore, heaters (91) (92) (93), so that the output value of this resin temperature sensor (3) indicates the temperature set value of the resin (25).
In particular, if the upstream heater (92) or (92), (93) is controlled, it is possible to perform injection filling at a resin temperature very close to the set value and without variation.

The resin (25) passing through the resin temperature sensor (3) undergoes a temperature change before reaching the gate (10). The temperature change is checked in advance, and the temperature change is calculated. If the temperature control of the state-of-the-art heater (91) is performed, more accurate injection filling becomes possible.

When the mold cavity (5) is filled with the resin (25), the servomotor (11) is actuated by a command from the control unit (24) to advance the gate cut pin (16), Close the gate (10) of the mold cavity (5) with. At this point, the mold cavity (5) is completely shut out from the outside world, so that the resin (25) does not enter or exit. Finally,
In this state, the mold is further clamped by the toggle mold opening / closing mechanism to compress the resin (25), followed by holding pressure and cooling,
Finally, the mold is opened and the product is taken out. This series of operations is repeated in injection molding intended for mass production, but the same molded product can be produced by equalizing the amount of resin charged for each molding.

Next, a second embodiment (A2) of the injection molding machine (A) according to the present invention will be described with reference to FIG. First embodiment (A1)
The parts that match are described briefly, and the differences are described in detail. This embodiment (A2) is a case of taking two pieces, and FIGS.
As shown in (1), mold cavities (5a) and (5b) are formed above and below the parting surfaces of the molds (1a) and (1b). Of course, the arrangement method is not limited to the upper and lower sides, and an appropriate method such as left and right and other appropriate methods are adopted. Here, an example in which the arrangement is performed vertically is taken as a representative example.

As in the first embodiment (A1), the injection cylinder (17)
The tip nozzle (18) matches the spool bush (19), and the spool bush (19) is connected to the hot runner (20). In the present embodiment (A2), the mold cavities (5a) (5
b) The hot runner (20)
Is branching on the way. Two branch hot runners (20a)
As in the first embodiment (A1), the heater (91a)
To (93b) and heater temperature sensors (41a) to (43b), respectively, and resin temperature sensors (3a) (3b) between heaters (91a) (92a) and (91b) (92b). Has been established.

Next, the operation of the second embodiment (A2) will be described. In this case, firstly, the upper, lower, left and right parts of the mold (1a) and (1b) have slight temperature differences due to the environment around the mold and other factors. Also, upper and lower branch hot runners (20a) (20b)
The same applies to. The resin (25a) (25b) injected from the injection cylinder (17) is then fed to the branch hot runner (20a) (20
Through b), they are led to the gates (10a) (10b) of the upper and lower mold cavities (5a) (5b). The state of the resin (25a) (25b) is the same before branching, but after branching, the temperature of the branched hot runners (20a) (20b) slightly changes depending on the state.

Therefore, in each branch hot runner (20a) (20b), as in the first embodiment (A1), each resin temperature sensor (3a) (3b)
The heaters (91a) to (93b) are controlled so that the output value coincides with the set temperature of the resin (25) .What is important here is that the resin temperature sensors (3a) and (3b) Are controlled so that the heaters (91a) to (93b) have the same value.

In other words, the resin flow hole (201a) at the branch portion
After passing through (201b) and branching, a resin with a slight temperature difference
(25a) and (25b) mean that the resin temperature is controlled at the outlet of the resin flow holes (201a) and (201b) and the resin is injected and filled. In this way, the upper and lower mold cavities as described above
(5a) and (5b) are filled with the same amount of resin (25a) (25b), and a molded article is taken out through a series of steps. Even in the case of two-cavity, two mold cavities (5a)
The precision base molded from (5b) is identical.

[0034]

According to the present invention, the temperature of the resin filled in the mold cavity is controlled by a resin temperature sensor disposed between heaters and not affected by heat from the heater. The amount of resin charged into the mold cavity can be equalized, and the same precision molded product can be mass-produced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold mechanism of an injection molding machine according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a mold cavity portion according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a mold mechanism of an injection molding machine according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a mold cavity portion according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a mold cavity portion of a conventional example.

[Explanation of symbols]

 (3) Resin temperature sensor (4) Heater temperature sensor (5) Mold cavity (9) Heater (10) Gate (25) Resin (201) Resin flow hole

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Yoshiaki Hara 1-4-4 Yatamachi, Shinjuku-ku, Tokyo F-term in Sony Music Entertainment Inc. (reference) 4F202 AP05 AR06 CA11 CB01 CK03 CN01 CN18 CN22 CN30 4F206 AP05 AR06 JA07 JL02 JN11 JP13 JP18 JQ81 JQ90

Claims (4)

[Claims] 1. A plurality of heaters disposed around a resin flow hole connected to a mold cavity, a heater temperature sensor disposed in accordance with the heaters, and a heater disposed between the heaters. And a resin temperature sensor disposed close to the resin flow hole. 2. A mold having a plurality of mold cavities, a plurality of heaters disposed around a resin flow hole connected to the mold cavities, and one heater An injection molding machine, comprising: a heater temperature sensor disposed in parallel, and a resin temperature sensor disposed between the heaters and disposed close to a resin passage. 3. A plurality of heaters disposed around a resin flow hole connected to a mold cavity, a heater temperature sensor disposed in accordance with the heater, and a heater disposed between the heaters. A resin temperature control method for an injection molding machine having a resin temperature sensor disposed in close proximity to the resin flow hole, wherein an output value of the resin temperature sensor is set to a set temperature of the resin passing through the resin flow hole. A resin temperature control method for an injection molding machine, wherein a heater is controlled so as to indicate a coincident value. 4. A mold provided with a plurality of mold cavities, a plurality of heaters disposed around a resin passage hole connected to the mold cavities, and one of the heaters. A method for controlling the temperature of an injection molding machine, comprising: a heater temperature sensor disposed in parallel with the heater; and a resin temperature sensor disposed between the heaters and disposed in close proximity to the resin passage. A resin temperature control method for an injection molding machine, wherein each heater is controlled so that an output value of a resin temperature sensor matches a set temperature of a resin passing through a resin flow hole and indicates the same value.