JP2002248653A - Injection machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an injection machine by shortening a screw and a heating cylinder. SOLUTION: The heating cylinder 11, a molding material supply means for supplying a molding material to the heating cylinder 11, and the screw 12 which is arranged in the heating cylinder 11 to be freely rotatable and freely forward/ backward movable and in which a compression zone Q2 and a metering zone Q3 are formed are provided. The molding material supply means has a conveyer for conveying the molding material, a preheating means for preheating the molding material, and a driving means for driving the conveyer. Since a supply part can be eliminated by the compression zone Q2 and the metering zone Q3 in the screw 12, the screw 12 and the heating cylinder 11 can be shortened, so that the injection machine can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin as a molding material heated and melted in a heating cylinder is injected at a high pressure and filled into a cavity space of a mold apparatus. A molded article can be obtained by cooling and solidifying in a space.

The injection molding machine has a mold device, a mold clamping device, and an injection device. The mold clamping device includes a fixed platen and a movable platen, and the mold is moved forward and backward by a mold clamping cylinder. The apparatus is closed, closed and opened.

On the other hand, the injection device has a heating cylinder for heating and melting the resin, and an injection nozzle for injecting the molten resin is attached to a front end of the heating cylinder, and a screw is provided in the heating cylinder. It is arranged rotatably and freely forward and backward. The screw is advanced by a driving unit disposed at the rear end, whereby the resin is injected from the injection nozzle. By rotating the screw, the resin accumulates (accumulates) in front of the screw. The resin is metered by rotating it by force. At this time, the screw is retracted by the reaction force of the resin.

[0005] By the way, a resin charging section is formed for supplying the resin to the heating cylinder, and the resin charging section includes a hopper, an opening / closing valve, a guide section, and a level gauge. Level is detected. Then, when the level of the resin becomes low as the injection and the measurement are repeated, the open / close valve is opened, and the resin in the hopper is supplied to the guide portion.

The screw includes a flight section and a screw head disposed at a front end of the flight section. The flight portion includes a flight formed in a spiral shape on a screw body, that is, an outer peripheral surface of the screw body, and the flight forms a spiral groove. In addition, the resin dropped from the hopper is supplied to the flight section in order from the rear to the front, a supply section for preheating the supplied resin, a compression section for compressing and melting the supplied resin, and a melting section. A measuring section for measuring a predetermined amount of the resin is formed. The bottom of the groove, that is, the outer diameter of the screw body is made relatively small in the supply part, gradually increased from the rear to the front in the compression part, and made relatively large in the metering part.

[0007]

However, in the above-mentioned conventional injection apparatus, the supply unit and the supply unit are provided for one screw.
Since the compression section and the metering section are formed, the length of the screw becomes longer, and accordingly the length of the heating cylinder becomes longer, so that the injection device becomes larger.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional injection device and to provide an injection device capable of shortening a screw and a heating cylinder and reducing the size.

[0009]

For this purpose, in the injection apparatus of the present invention, a heating cylinder, a molding material supply means for supplying a molding material to the heating cylinder, a rotatable interior of the heating cylinder, and A screw that is provided to be able to advance and retreat, and has a compression unit and a metering unit;

[0010] The molding material supply means includes a carrier for conveying the molding material, a preheating means for preheating the molding material conveyed by the carrier, and a driving means for operating the carrier.

In another injection device of the present invention, the carrier is a feed screw. And
The feed screw is rotated by driving the driving means, and includes an auger for continuously moving the molding material with the rotation.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an injection device according to an embodiment of the present invention.

In the drawing, 11 is a heating cylinder as a cylinder member, 12 is a screw as an injection member which is rotatably disposed within the heating cylinder 11 and is capable of moving forward and backward (moving in the left-right direction in the drawing). 13 is an injection nozzle formed at the front end (left end in the drawing) of the heating cylinder 11, 14 is a nozzle port formed in the injection nozzle 13, and 15 is a position near the rear end (right end in the drawing) of the heating cylinder 11. A resin inlet 16 as a molding material inlet formed at a predetermined position,
The resin introduction path 31 is formed in the temperature adjustment block 16, and the lower end of the resin introduction path 31 communicates with the resin introduction port 15. A drive unit (not shown) is provided at the rear end of the heating cylinder 11 for rotating the screw 12 or moving the screw 12 forward (moving to the left in the drawing).

On the outer periphery of the heating cylinder 11, planar heaters h1 to h3 are arranged. By energizing the heaters h1 to h3, a resin (not shown) as a molding material is heated and melted. it can. The temperature control block 16 includes a temperature controller and pipe lines 16a and 16b (not shown).
And preheats the resin in the resin introduction path 31 by a temperature control medium supplied from the temperature controller to maintain the resin at a predetermined temperature, and introduces the resin by the heat transmitted from the heaters h1 to h3. The resin in the passage 31 is prevented from being melted.

The screw 12 has a flight section 21,
And a screw head 27 disposed at the front end of the flight section 21. The flight part 21 is a flight 2 formed in a spiral shape on the outer peripheral surface of the screw body.
The flight 23 forms a spiral groove 24. In addition, the flight section 21 has an introduction section Q1 into which the resin is introduced via the resin introduction port 15 in order from the rear (the right in the figure) to the front (the left in the figure), while compressing the introduced resin. A compression section Q2 for melting and a measuring section Q3 for measuring a fixed amount of the melted resin at a time.
Is formed. The bottom of the groove 24, that is, the outer diameter of the screw body is relatively small at the introduction portion Q1,
The pressure is gradually increased from the rear to the front in the compression section Q2, and is relatively increased in the measurement section Q3. Therefore, the gap (gap) between the inner peripheral surface of the heating cylinder 11 and the outer peripheral surface of the screw main body is made relatively large in the introduction part Q1, and is gradually reduced from the rear to the front in the compression part Q2. It is made relatively small in Q3. In the present embodiment, the introduction part Q1 is formed, but it is not always necessary to form the introduction part Q1.

The measuring section Q3 has a length of about four pitches of the flight 23 in the axial direction.
When the screw 12 is set at the forward limit position as shown in the figure, that is, at the measurement start position, the screw 12 is exposed to the resin introduction port 15, and the compression section Q2 and the measurement section are set. Q3 is the resin inlet 15 in the axial direction.
It is located more forward. In this case, the screw 12
At the weighing start position, the introduction section Q1 and the heaters h1 to h
3 is separated by the temperature control block 16, the introduction portion Q1 has no preheating function, and the resin is not heated. Therefore, the resin is advanced in the groove 24 and is heated only when the resin reaches the compressed portion Q2.

A resin supply section 17 is formed as a molding material supply section for supplying a resin to the heating cylinder 11. The resin supply section 17 is provided with the temperature control block 16.
Attached to the top of The resin supply unit 17 includes a feed screw 18 as a rotary transfer body that transfers the resin by a set amount, and is disposed near a rear end of the feed screw 18, and a hopper into which the resin in the form of pellets is charged. 19, and the feed screw 18 and the temperature control block 16
And a cylindrical guide part 20 for connecting the two. The guide section 20
A guide path 33 is formed in the inside, and the guide path 33 transfers the resin conveyed by the feed screw 18 to the resin introduction path 3.
Guide to 1. The resin introduction path 31 and the guide path 33 in the heating cylinder 11 are hermetically sealed by a feed screw 18, and a vacuum pump (not shown) serving as a negative pressure generating means is connected to the guide section 20. Therefore, by driving the vacuum pump, the heating cylinder 11
Negative pressure can be generated within.

The feed screw 18 includes a case 41 having a rectangular cross section, and an auger 43 as a supply unit rotatably supported in the case 41.
The auger 43 is rotated by driving a supply motor 51 as a supply driving means,
The resin is continuously moved in the axial direction with the rotation.

For this purpose, a resin supply port 54 as a molding material supply port communicated with the hopper 19 is provided on the upper surface near the rear end of the case 41 with the front end of the auger 43 facing the front end of the case 41. A resin discharge chamber 61 is formed as a molding material discharge chamber for discharging the resin. At a lower end of the resin discharge chamber 61, a resin discharge port 55 as a molding material discharge port communicated with the guide path 33 is formed. It is formed.
The auger 43 includes a main body portion 56 and a shaft portion 57 formed at a rear end of the main body portion 56. The shaft portion 57 is fitted into the sleeve 60. The sleeve 60 is supported on the case 41 by bearings b1 to b3. The main body 56 includes a flight 58 spirally formed on the main body of the auger 43, that is, the outer peripheral surface of the auger main body, and the flight 58 forms a spiral groove 59. A planar heater h4 as preheating means is provided on the outer periphery of the case 41.
Is disposed, and the resin conveyed by the feed screw 18 is preheated by the heater h4. The feed screw 18, the supply motor 51 and the heater h4 constitute a molding material supply unit.

Accordingly, when the supply motor 51 is driven, the resin in the hopper 19 is supplied into the case 41 through the resin supply port 54 with the rotation of the auger 43, and the resin in the groove 59 is continuously fed. It is moved forward, and is heated by the heater h4 during that time, preheated to a predetermined temperature, discharged to the resin discharge chamber 61, and further discharged to the guide path 33 through the resin discharge port 55. Subsequently, the resin is guided by the guide path 33, passes through the resin introduction path 31, and is introduced into the heating cylinder 11 through the resin introduction port 15. In this manner, the resin in the hopper 19 is
And is supplied into the heating cylinder 11 by the set amount.

A photosensor 30 as a molding material detecting means is provided just above the resin inlet 15 in the resin inlet path 31 so as to face the inlet Q1. The photo sensor 30 detects the resin in the groove 24 in the introduction portion Q1 and generates a sensor output proportional to the amount of the resin in the groove 24. Note that the sensor output is used to control the amount of resin supplied to the heating cylinder 11.

Next, an injection control device for operating the injection device having the above configuration will be described.

FIG. 2 is a block diagram showing an injection control device according to the embodiment of the present invention, and FIG. 3 is a diagram showing plastic characteristics of the injection device according to the embodiment of the present invention. 3, the horizontal axis represents the rotational speed of the screw 12 (FIG. 1), that is, the screw rotational speed N, and the vertical axis represents the retreat speed of the screw 12, that is, the screw retreat speed Vr.

In FIG. 2, 75 is a control unit, 51 is a supply motor, 76 is a weighing motor, 77 is an injection motor,
78 is a vacuum pump connected to the guide unit 20, 80 is a memory as a recording means, 30 is a photo sensor, 81 is a screw position sensor as a screw position detecting means for detecting the position of the screw 12, that is, a screw position, and 82 is a screw position sensor. A metering speed sensor for detecting the rotation speed of the metering motor 76, an injection speed sensor 83 for detecting the rotation speed of the injection motor 77, and a supply speed sensor 84 for detecting the rotation speed of the supply motor 51. . A drive unit is constituted by the weighing motor 76, the injection motor 77, and the like.

A ball screw (not shown) for converting the rotational motion generated by the injection motor 77 into a linear motion is disposed behind the heating cylinder 11 and the rotational speed of the ball screw is measured by the screw position sensor 81. And the screw position can be calculated based on the rotation speed. Further, the weighing speed sensor 82, the injection speed sensor 83, the supply speed sensor 84, and the like are all constituted by encoders.

First, when the control unit 75 drives the vacuum pump 78, the air in the heating cylinder 11, the resin introduction path 31 and the guide path 33 is sucked, and the negative pressure is applied to the heating cylinder 11, the resin introduction path 31 and the guide path 33. Pressure is generated. Next, a weighing control unit (not shown) of the control unit 75 starts a weighing process, generates a weighing start signal, sends the signal to the weighing motor 76, and drives the weighing motor 76 to rotate the screw 12. . The weighing control unit sends the weighing start signal to the supply motor 51,
The auger 43 is rotated by driving the supply motor 51. Along with this, the resin in the hopper 19 is supplied to the auger 43 via the resin supply port 54, is continuously advanced in the groove 59, is preheated during that time, and is discharged to the resin discharge chamber 61. Then, the resin is supplied to the guide path 33.
Then, it passes through the resin introduction path 31 and is further introduced through the resin introduction port 15 into the introduction section Q1 in the heating cylinder 11. The resin introduced into the introduction section Q1 advances in the groove 24 with the rotation of the screw 12, becomes a semi-molten state in the compression section Q2, is completely melted in the measuring section Q3, becomes liquid, and becomes a liquid. It is stored ahead of 27.

During this time, the vacuum pump 78 continues to be driven, and a negative pressure is generated in the heating cylinder 11, the resin introduction passage 31 and the guide passage 33. Therefore, the air that has entered the heating cylinder 11, the resin introduction path 31 and the guide path 33, and the gas and the like generated along with the measurement are discharged, so that the occurrence of resin burning can be prevented. Can be.

Subsequently, based on a signal from the screw position sensor 81, when it is found that the screw 12 has reached a predetermined measurement end position, the measurement control means
The weighing process is completed, a weighing end signal is generated and sent to the weighing motor 76, and the rotation of the screw 12 is stopped by stopping the driving of the weighing motor 76. Further, the weighing control unit sends the weighing end signal to the supply motor 51, and stops the rotation of the auger 43 by stopping the drive of the supply motor 51.

Next, an injection control means (not shown) of the control unit 75 starts the injection process, generates an injection start signal, sends the signal to the injection motor 77, and drives the injection motor 77 to move the screw 12 forward. Let it. Along with this, the resin stored in front of the screw head 27 is injected from the injection nozzle 13.

In the measuring step, the amount of resin introduced into the introduction section Q1 by the resin supply section 17 and the amount of resin moved in the groove 24 and stored in front of the screw head 27 are determined. Are equalized.
For this purpose, the supply amount setting processing means (not shown) of the control unit 75 starts the photo sensor 30 when the measuring process is started.
Is read, and the target rotation speed of the supply motor 51 corresponding to the sensor output is read out with reference to a supply motor rotation speed table (not shown) of the memory 80, and the rotation speed of the supply motor 51 is set to the target rotation speed. The supply motor 51 is driven so that the supply amount is set.
In this case, the rotation speed of the supply motor 51 is detected by the supply speed sensor 84, and feedback control is performed.

As a result, in the introduction section Q1, the state of the resin is reduced, and the groove 24 is not filled with 100% of the resin.

On the other hand, in the compression section Q2 and the measuring section Q3, the state of the resin is made dense, and
0% is satisfied. Then, 100 resin is filled in the groove 24.
[%] The rearmost position of the portion to be filled is substantially located at the boundary between the compression section Q2 and the introduction section Q1. When the introduction part Q1 is not formed, the compression part Q
2 at the rear end of the compressed portion Q2.
4 is filled with 100% of resin.
In 5, the supply motor 51 is controlled so that the resin does not fill beyond the height of the flight 23.

The plasticizing ability represented by the screw rotation speed N and the screw retreating speed Vr is determined by the type, dimensions, specifications and the like of the injection device, but is lower than the plasticizing ability standard line Ls shown in FIG. That is,
It is set to fit in the hatched part. For example, in the plasticizing capacity standard line Ls, when the screw retreat speed Vr is the value v when the screw rotational speed N is the value n, the rotation of the supply motor 51 is performed when the screw rotational speed N is fixed at the value n. By adjusting the speed, the screw retreat speed Vr is set to Vr <v.

When the screw retreat speed Vr is fixed at the value v, the screw rotation speed N is set to N> n by adjusting the rotation speed of the supply motor 51. That is, the metering is performed in the region on the low speed side and the high rotation side with respect to the plasticizing ability standard line Ls.

By setting as described above, the resin can be introduced into the introduction section Q only during the weighing process and in an amount required for weighing.
1, the resin is not stored in the resin introduction path 31.

Therefore, the screw 12 has a compression part Q2
And the metering section Q3, it is not necessary to form the supply section.
1 can be shortened. The screw 12
And the auger 43 are disposed in parallel, and when the screw 12 is placed at the measurement end position, the screw 12 and the auger 43
Are overlapped in the axial direction, so that the injection device can be downsized.

Further, it is not necessary to form a supply section in the screw 12, and the state of the resin is reduced in the introduction section Q1.
The frictional resistance between the inner peripheral surface and the resin can be reduced. As a result, the torque required to rotate the screw 12 is reduced, and the drive unit can be downsized accordingly.

In the measuring step, the heating cylinder 11
Since the frictional resistance between the inner peripheral surface of the resin and the resin can be reduced, it is possible to prevent the resin from generating heat by shearing. Therefore, the amount of heating by the heaters h1 to h3 can be easily controlled.

Since a negative pressure is generated in the heating cylinder 11, the resin does not come into contact with air even if the state of the resin is reduced. Therefore, it is possible to prevent the resin from being oxidized by air.

The present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0042]

As described above in detail, according to the present invention, in the injection apparatus, the heating cylinder, the molding material supply means for supplying the molding material to the heating cylinder, and the interior of the heating cylinder are rotatable. And a screw which is provided so as to be able to move forward and backward, and has a compression section and a measuring section.

The molding material supply means includes a carrier for conveying the molding material, a preheating means for preheating the molding material conveyed by the carrier, and a driving means for operating the conveyance body.

In this case, it is sufficient to form a compression section and a metering section in the screw, and it is not necessary to form a supply section, so that the screw and the heating cylinder can be shortened. Therefore, the size of the injection device can be reduced.

Further, since it is not necessary to form a supply section on the screw, the frictional resistance between the inner peripheral surface of the heating cylinder and the resin can be reduced in the measuring step. As a result, the torque required to rotate the screw is reduced, and the drive unit can be downsized accordingly.

Further, since the frictional resistance between the inner peripheral surface of the heating cylinder and the resin can be reduced in the measuring step, it is possible to prevent the resin from generating heat generated by shearing. Therefore, the amount of heating by the heater of the heating cylinder can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an injection device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an injection control device according to the embodiment of the present invention.

FIG. 3 is a diagram showing plastic characteristics of an injection device according to an embodiment of the present invention.

[Description of Signs] 11 Heating cylinder 12 Screw 18 Feed screw 43 Auger 51 Supply motor h4 Heater Q2 Compression unit Q3 Measuring unit

Claims (2)

[Claims] (A) a heating cylinder; and (b) a molding material supply means for supplying a molding material to the heating cylinder.
(C) rotatably in the heating cylinder, and
And a screw provided with a compression section and a metering section so as to be able to move forward and backward, and (d) the molding material supply means is configured to transport a molding material, An injection apparatus comprising: a preheating means for preheating; and a driving means for operating the carrier. 2. The auger wherein (a) the carrier is a feed screw, and (b) the feed screw is rotated by driving the driving means, and continuously moves the molding material with the rotation. The injection device according to claim 1, further comprising: