JPS62130820A - Injection molder - Google Patents

Abstract

PURPOSE:To provide an injection molder, which allows to precision-mold at high speed, by a method wherein the rate of feed of molten resin is feedback controlled on the basis of the resin pressure detection signal sent from a sensor which is provided in the midway of a piston driving system in order to detect the resin pressure in an injection chamber under the condition that the retreating speed of a piston is held at constant. CONSTITUTION:Before molten resin 82 is charged in an injection chamber 38, an injection servo motor 16 is rotated at a constant low speed in order to hold the retreating speed of a plunger 44. The resin pressure is applied to an injection reaction sensor 51 and consequently the resin pressure detection signal is inputted through an A/D converter 85 to a control part main body 88. Desired charging pressure to the injection chamber 38 is inputted through a setter 86 in the RAM of the control part main body 88. A CPU compares the measured resin pressure with the set charging pressure. If deviation exists between said pressures, the control signal which is calculated so as to bring the measured resin pressure to be equal to the set charging pressure is inputted from the control part main body through an A/D converter and a servo amplifier to a motor 15 so as to regulate the rotational speed of the motor 15 in order to control the charging pressure to the injection pressure at constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding machine, and particularly to an injection molding machine capable of high-speed molding and precision molding.

[Background of the invention]

In recent years, speed and pressure have become the driving sources for injection molding machines.

The use of servo motors is being considered for various reasons, including easy position feedback control, good responsiveness, and stable operation even at low speeds.

As a method for controlling the back pressure of the screw in this servo motor driven injection molding machine, for example, Japanese Patent Laid-Open No. 58-17963
A control method as described in Publication No. 1 has been proposed.

This back pressure control method converts the backward movement of the screw, which occurs when charging the molten synthetic resin by the rotation of the two screws, into a rotational movement using a gear means, and converts the rotational force into mvx using a brake means, thereby controlling the back pressure of the screw. It is an attempt to control the

However, in this control method, gear means are used to convert the backward movement of the screw into rotational movement, and brake means are used to control the rotational movement obtained by conversion, so it is not possible to achieve stable It has the disadvantage that accurate back pressure control is difficult.

On the other hand, toggle type mold clamping devices and direct pressure type mold clamping devices have been conventionally employed as mold clamping devices for injection molding machines. All of these devices are hydraulically driven, and the mold clamping operation is performed by switching the flow direction of the pressure oil between forward and reverse at a predetermined timing, so it is necessary to use a valve to switch the flow direction. There is a delay before the pressure reaches a predetermined level, which hinders high-speed operation.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection molding machine capable of high-speed molding and precision molding by eliminating the drawbacks of the prior art described above.

[Summary of the invention]

In order to achieve the above-mentioned objects, the present invention provides a heating cylinder and an injection nozzle disposed on the tip side of the heating cylinder.

For example, a half-immersed resin supply needle such as a screw that supplies molten resin to the injection chamber provided at the tip of the heating cylinder. Same, opposite backward direction l\8
hy=--, 2-liter 2-sho mechanism I is provided with piston means such as a plunger for injecting the molten resin supplied to the sealing chamber into the upper cylindrical chamber through the injection nozzle.

#JI7 of the injection chamber in the drive system of the piston means during piston movement! #In order to maintain the resin pressure in the injection chamber constant during charging by providing a sensor, such as a load cell, that detects the pressure.

The retracting speed of the piston means is held constant, and the supply speed of the molten resin by the resin supply means is feedback-controlled based on the resin pressure detection signal from the sensor. It is.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. 1st
v! J is a schematic layout diagram of the main parts of the injection molding machine as seen from the front.

First, the overall schematic configuration of the injection molding machine will be explained using FIG. 1. 1 in the figure is the base of the injection molding machine,
On the upper front side of the machine, an operation/display panel section 2 is provided on the right side as viewed in the drawing, and a shoe 1-3 for discharging molded products is provided on the left side.

Figure 2 is a front view of the operation/display panel section 2, in which 4 is the teaching source switch, 5 is the connection part for the teaching box which will be described later, 6 is the operation power switch, 7 is the heater switch, and 8 is the operation key. In one group, manual operation, semi-automatic operation,
It consists of operation keys for automatic operation, motor activation, nozzle forward, nozzle retract, mold opening/closing, injection molding, etc. 9 is a code display section consisting of 4-digit seven segments, and 10 is an emergency stop button.

Returning to FIG. 1 again, the schematic structure of the injection molding machine will be explained. An injection cover 11. A safety door 12 and a crank cover 13 are provided.

A hopper 14 for charging pellet-shaped molding material is provided on the injection cover 11, and inside there are a charging servo motor 15, an injection servo motor 16, a nozzle touch limit switch 17, and a nozzle touch back motor 18. Additionally, a heating cylinder housing a screw, which will be described later, is provided.

A fixed die plate 19, an S-moving die plate 20, and a tie bar 21 are provided inside the safety door 12. Also, inside the crank cover 13 is a mold thickness adjustment motor 22. A mold opening/closing servo motor 24 is provided at the tail stock 23 and below it.

The arrangement of the main parts of the injection molding machine is as shown in FIG. 1. Next, the injection mechanism and mold clamping mechanism of this injection molding machine will be explained.

First, the structure of the injection mechanism will be described in detail with reference to FIGS. 3 to 9.

Figures 3 and 4 are a plan view and a front view showing the schematic structure of the injection molding machine, Figure 5 is a sectional view of the vicinity of the injection screw, Figure 6 is a sectional view of the vicinity of the slide chamber, and Figure 7 is a sectional view of the vicinity of the slide chamber. FIG. 6 is a sectional view taken along the line I--I, FIG. 8 is a plan view of the vicinity of the slide chamber, and FIG. 9 is a sectional view of the vicinity of the plunger tip.

A heating tube 26 is provided at the front of the injection section main body 25, and a screw 27 is rotatably inserted into the heating tube 26. The rear end of the screw 27 is engaged with a gear 29 by a plurality of keys 28 arranged in the circumferential direction as shown in FIG. As shown, it meshes with the drive side gear 30 of the charging servo motor 15, and these gears 29 and 30 are both supported by the injection part main body 25 via a ball bearing 31. Therefore, the rotational driving force of the charging servo motor 15 is transmitted to the screw 27 via the gear 30, the gear 29, and the key 28, and the screw 27 is rotationally driven in a fixed direction.

As shown in FIG. 5, the injection part main body 25 and the heating cylinder 2
A pellet input hole 36 is formed at a predetermined position of 6, and the hopper 14 and the heating cylinder 26 are connected through this pellet input hole 36.
The hollow parts of the two are connected.

As shown in FIG. 6, a cylinder member 37 is fixed inside the tip of the heating cylinder 26, and this cylinder member 37 is composed of a front end 37a, an intermediate part 37b, and a rear end 37c. An injection chamber 38 is formed in the center of the front end portion 37, I in the axial direction, and the rear portion of the front end portion 37a expands into a cone shape toward the intermediate portion 37b. A plurality of passages 39 are provided in the vicinity of the outer periphery of the intermediate portion 37b in the axial direction.
A slide chamber 40 extending in a direction perpendicular to the axial direction is provided in the center of the intermediate portion 37b, and a slide hole 41 is formed forward from the center of the slide chamber 40. An introduction hole 42 is provided in the center of the rear end portion 37c in the axial direction, and the front portion thereof is connected to the intermediate portion 37b.
The sides expand into a bowl-like shape.

A plunger 44 having approximately the same diameter as these is slidably inserted from the front slide hole 41 formed in the intermediate portion 37b to the injection chamber 38 of the front end portion 37a, and near the tip thereof there is a plunger 44 extending from the outer periphery toward the center. It has one or more extending radial holes 45 (see FIG. 9) and an axial hole 46 communicating with the radial holes 45 and opening toward the distal end surface of the plunger 44. As shown in FIG. 6, the diameter of the axial hole 46 becomes larger from the middle, and a ball 47 and a retaining pin 48 are inserted into the larger diameter portion.

The rear end of the plunger 44 is screwed to a holder arm 49, and both ends of the holder arm 49 protrude outward from the heating cylinder 26, as shown in FIG. 8, and both ends are connected to an injection bar 50. An injection reaction force sensor 51 consisting of a load cell is interposed in the middle of one injection bar 50.

As shown in FIG. 3, the rear ends of both injection bars 50 are each connected to the tip of a driver 52, and a screw hole is formed in the center of the driver 52 along the axial direction, and a screw is inserted into the screw hole. A cylindrical body 53 is screwed into it.

As shown in FIG. 5, this threaded cylindrical body 53 is rotatably supported by a ball bearing 31, and has a threaded portion 54 formed on its outer periphery to be screwed into the drive body 52.

As shown in FIG. 4, a gear 55 is attached to the rear end of the threaded cylinder 53, and the gear 55 meshes with a driving gear 56 of the injection servo motor 16. Therefore, the rotational driving force of the injection servo motor 16 is applied to the drive side gear 56. Gear 55° threaded cylinder 53, drive body 52. Injection bar 50. It is also transmitted to the plunger 44 via the holder arm 49, and the plunger 4 is
4 moves forward and backward.

As shown in FIG. 6, a needle 57 is arranged behind the holder arm 49 and extends toward the orifice 34.
It is separate from the holder arm 49. A nozzle 58 is attached to the tip of the cylinder member 37, and a plurality of thermocouples 59 and heaters 60 are arranged in pairs at the tip of the cylinder member 37 and the outer periphery of the heating W126. Wrapped in place.

Next, the structure of the mold clamping mechanism will be explained. 10 and 11 are a plan view and a front view of the mold clamping section.

Four tie bars 21 are installed between the housing 61 and the fixed die plate 19 and are arranged at predetermined intervals. The movable die plate 20 is movably arranged with respect to the fixed die plate 19 using the tie bar 21 as a guide, and the fixed side mold 62 is mounted on the fixed die plate 19.

The movable molds 63 are each fixed to the movable die plate 20, and the movable molds 63 can be moved into and out of contact with the fixed mold 62.

A bracket 64 is provided protruding from the movable die plate 20, and the plain end of a crank arm 66 is connected to the bracket 64 via a pin 65.

As shown in FIG. 4, a mold opening/closing servo motor 24 is installed below the housing 61, and a bearing 69 (
The base end portion of the crank arm 66 is rotatably connected to the crank arm 66 via the crank arm 66 (see FIG. 11). Therefore, the driving force of the mold opening/closing servo motor 24 is applied to the crankshaft 67, the eccentric shaft portion 68,
It is transmitted to the moving die plate 20 via the crank arm 66 and the bracket 64, and is transmitted to the servo motor 24.
The rotational movement is converted into a forward and backward movement by the crank mechanism, and the movable mold 63 is moved toward and away from the stationary mold 62.

As shown in FIGS. 4 and 11, the housing 61
A mold thickness adjustment motor 2 is connected above the bracket 70.
2 is attached, and its drive side is connected to each tie bar 21 via a gear group 71, so that mold thickness can be adjusted by rotation of the motor 22.

FIG. 12 is a perspective view of the teaching box. On the top surface of the box body 72, there are provided input keys such as a numeric keypad 73, a menu key 74, a cursor key 75, an on key 76, a reset key 77, an entry key 78, and a display section 79. This box body 72
An optical fiber cable 80 and a metacon 81 are connected to the terminal, and these are inserted into the teaching box connection section 5 of the operation/display panel 2 shown in FIG. By using this teaching pendant,
There is the convenience of being able to set various molding data even at a location away from the molding machine main body.

Next, the operation of this injection molding machine will be explained.

In the state shown in FIGS. 5 and 6, the charging servo motor 15 is driven to rotate the screw 27, and resin pellets as a molding material are introduced from the hopper 14 and supplied to the heating cylinder 26. Supplied synthetic resin 8
2 is plasticized and melted by the rotation of the screw 27 and is fed into the slide chamber formed by the cylinder member 37.

Further, the molten resin 82 is transferred to the radial hole 45. The axial bore 46, the injection chamber 38 and the nozzle 58 are filled. The ball 47 is pushed forward by the pressure of the filled molten resin 82, but the bottle 48 prevents it from coming off. In this way.

A certain amount of molten resin 82 is filled into the injection chamber 38 .

As shown in FIG. 6, the injection servo motor 16 is driven in the forward rotation direction in a state filled with the molten resin 82.

This drive causes the drive side gear 56 shown in FIG. gear 5
5 and the threaded cylinder body 53 rotate, and with the rotation, the drive body 52. The plunger 44 advances toward the mold side via the injection bar 50 and the holder arm 49.

As a result of this forward movement, the ball 47 receives ma pressure and immediately retreats, so that the small diameter portion of the axial hole 46 is closed by the ball 47, as shown in FIG. In other words, this ball 47 and the small diameter portion of the axial hole 46 stop the valve! It constitutes @II. By moving the plunger 44 forward in this state, the molten resin 82 is transferred from the nozzle 58 to the molds 62 and 63.
It is ejected inside.

The injection amount of the molten resin 82 is determined by the stroke length of the plunger 44, and the stroke length of the plunger 44 can be adjusted by changing the amount of rotation of the injection servo motor 16. It is important to determine the final injection amount by looking at the finished molded product, and to set the stroke length of the plunger 44 so as not to cause sink marks or cracks in the molded product.

The injection molding process consists of a filling process in which the cavity is filled with molten resin, and a pressure holding process in which the resin in the cavity is suppressed until the resin solidifies in the cavity.

During this pressure holding step, the molten resin 82 is supplied and filled into the accumulator chamber described above. FIG. 13 is a sectional view of the main part at the time of completion of this pressure holding process.

After this pressure holding process is completed, by rotating the injection servomotor 16 in the reverse direction, both the plunger 44 and the holder arm 49 move backward as shown in FIG. As a result of this movement, the ball 47 receives resin pressure and immediately moves toward the temporary stopper 48, opening the small diameter portion of the axial hole 46, and as the plunger 44 moves, a portion of the molten resin 82 is transferred to the radial hole. 45 and the axial hole 4G into the injection chamber 38.

Next, the opening/closing operation of the mold will be explained. FIG. 15 is a front view showing the mold opening state of the mold clamping section. In this state, the movable die plate 20 is the most retracted.

A sufficient distance is maintained between the movable mold 63 and the fixed mold 62. When the mold opening/closing servo motor 24 (see FIG. 4) is driven to rotate the crank 41III 67 based on a mold clamping signal from the control section, the eccentric shaft portion 68 rotates around the crank shaft 67.

With this rotation, the movable die plate 20 moves straight through the crank arm 66 while being guided by the tie bars 21, and the movable mold 63 approaches the fixed mold 62. Then, when the mold opening/closing servo motor 24 has rotated 180 degrees, as shown in FIG. 10, the central axis P of the crank arm 66 coincides with the rotation center 0 of the crankshaft 670, and the crank arm 66 is in the most extended state. The movable mold 63 comes into pressure contact with the stationary mold 62, and strong mold clamping is performed.

In this state, the rotation of the mold opening/closing servo motor 24 is stopped, the movement of the movable die plate 20 is stopped, and the resin is filled into the cavity and the pressure is maintained as described above.

When the injection molding process is completed in this way, when the mold opening/closing servo motor 24 is driven again to rotate the crankshaft 67 in the same direction, the moving die plate 20 (moving side mold 6
3) is separated from the fixed die plate 19 (fixed side mold 62) and the mold is opened.

In connection with this mold opening operation, the eject rod 83, which had been retracted until now, moves forward and ejects the molded product inside the movable mold 63, and the molded product passes through the chute 3 (see Fig. 1) and enters the machine. It is discharged outside. After the molded product is ejected in this manner, the crankshaft 67 rotates in the same direction to clamp the mold, and the eject rod 83 retreats as the spring 92 (see Figure 3) is compressed. .

FIG. 16 is a characteristic diagram showing the relationship between the rotation angle θ of the crankshaft 67 and the moving speed V of the movable die plate 20.

The position where the movable die plate 20 is farthest from the fixed die plate 19, that is, the eccentric portion 6 of the crankshaft 67
1.8 as shown in FIG. The mold opening/closing servo motor 24 is driven to rotate the crankshaft 67 from the position tAc rotation angle θ; 0 degrees, which is directly behind this.

As shown in the figure, the moving speed V is slow at the beginning of rotation, but becomes faster when the rotation angle 0 is around 90 degrees, and after that, the moving speed V is gradually decelerated. Rotation angle θ is 18
When the angle approaches 0 degrees, the movable die 63 comes into contact with the stationary die 62, and as the one rotation angle θ increases, the contact force also increases. The range is ±0.1 degree for a rotation angle of 180 degrees (in Fig. 16).

It is shown enlarged as a hatched part. ) is detected by an angle sensor 84 (see Fig. 4) such as an encoder attached to the drive shaft of the servo motor 24 for mold opening/closing, the control unit detects that the rotation angle θ of the crankshaft 67 is 18
It is determined that the dead center of 0 degrees has been reached, and the rotation of the mold opening/closing servo motor 24 is stopped.

The movement of the moving die plate 20 is stopped. In this state, the injection and pressure holding described above are performed.

When the injection 5 holding pressure is completed, the crankshaft 67 is further 18
In the injection molding machine of the present invention, the movable die plate 20 is rotated 0 degrees to open the mold, and the movable die plate 20 returns to its original position to complete one cycle of mold opening and closing. The movable die plate is reciprocated to perform mold clamping and mold opening with respect to the fixed die plate. Therefore, the structure is simple, and the movable die plate can smoothly reciprocate, allowing the injection molding machine to operate at high cycles. Furthermore, by using a servo motor as the drive source for the mold opening/closing operation, the accuracy of stopping the crank at its dead center can be improved.

FIG. 17 is a control system block diagram of the charging servo motor 15. 51 in the figure is an injection reaction force sensor, 85 is A
D converter, 86 is a charge pressure setting device, 88 is a control unit main body, although not shown, I10 boat, μmc pu, RA
6 or 89 is a DA converter, 90 is a servo amplifier, and 15 is a charging servo motor.

When charging the molten resin 82 into the injection chamber 38, the injection servo motor 16 is rotated at a constant speed at a relatively low speed to keep the retraction speed of the plunger 44 constant. Therefore, resin pressure is applied to the injection reaction force sensor 51 interposed in the middle of the injection bar 50, and the resin pressure detection signal is inputted to the control unit main body 88 through the AD converter 85. In addition, this control unit main body 8
A desired charge pressure (resin pressure) in the injection chamber 38 is input to the RAM No. 8 through the charge pressure setting IPF 36. Therefore, the resin pressure actually measured by the injection reaction force sensor 51 and the set charge pressure are compared by the CPU, and if there is a deviation between the set charge pressure and the measured charge pressure,
A control signal calculated to achieve the set charge pressure is input from the control section main body 88 to the servo motor 15 through the DA converter 89 and the servo amplifier 90. In the servo motor 15, the rotation speed is set to W8 according to the input control signal.
! 1.

Thereby, the charge pressure in the injection chamber 38 is controlled to be always constant. Although not shown, the rotational speed of the injection servomotor 16 is self-controlled by an attached rotational speed detection means such as a tachogenerator so that the rotational speed is always constant. As described above, by feedback control using the injection reaction force sensor 51.

The charge density of the molten resin 82 can always be maintained constant.

As shown in FIGS. 3 and 8, an injection reaction force sensor 51 is interposed in the middle of the injection bar 50, which also performs pressure holding control.6 Next, this pressure holding control will be briefly explained.

In order to improve the dimensions and surface accuracy of molded products and to prevent molding distortion and cranking, systems are used to perform injection molding by varying the injection speed and holding pressure of molten resin in multiple stages. FIG. 18 is a diagram showing an example of this pressure holding pattern.

In this figure, the horizontal axis shows time (T), and the vertical axis shows pressure (P). Point G in the figure is the time when pressure holding is switched, point H is the time when holding pressure is completed, and between points G and H. This is the pressure holding process. In this example, the pressure during the pressure holding process is set to be gradually lowered over time in three stages: first holding pressure Pi, second holding pressure P2, and third holding pressure P3. Such a holding pressure pattern is appropriately set depending on the shape, size, dimensional accuracy, surface accuracy of the molded product, and molding conditions such as the molding material used.

Setting of such a holding pressure pattern is performed by a holding pressure setting device and is stored in the RAM of the control unit main body. During the pressure holding process, pressure is applied to the resin in the cavity by the injection bar 50 via the plunger 44, and the pressurizing force at this time, in other words, the reaction force transmitted by the plunger 44 by the nine-bar resin is applied to the injection bar 50. It is electrically detected by an injection reaction force sensor 51 provided in the middle.

This detection signal is input to the control unit main body through the AD converter, and the holding pressure (first holding pressure Pz,
The second holding pressure P=, the third holding pressure pz) are compared from time to time, and if there is a deviation between the set holding pressure and the measured holding pressure, a control signal calculated to reach the set holding pressure is sent to the control unit. The signal is input from the main body to the servo motor 16 through a DA converter and a servo amplifier. The servo motor 16 adjusts the supplied current, that is, the output torque, based on the input control signal, thereby controlling the holding pressure by the plunger 44 to the set holding pressure.

As in this embodiment, injection bars 50 are connected to both ends of a holder arm 49 that supports a plunger 44, respectively. If the so-called single-sided type structure is used, the reciprocating movement of the plunger 44 is smoother and the operation reliability is higher than that of the cantilever type. Furthermore, by using two injection bars 50, the injection reaction force transmitted from the plunger 44 to one injection bar 50 can be reduced by half, so that the injection reaction force attached to either injection bar 50 can be reduced by half. The force sensor 51 may be an inexpensive load cell with low pressure sensing ability.

The data from the above-mentioned injection reaction force sensor 51 is read by a sampling signal periodically output from the control section main body 88.

19 and 20 are injection force characteristic diagrams of a molding machine of the present invention and a conventional molding machine. In these figures, curve X is 1 when the injection force is set to 1200 kg/-
Curve Y is an actual measurement curve when the injection force is set at 2900 kg/cJ, and in each test, the measurement is repeated 10 times and shows the state of variation in the injection force.

In a conventional injection molding machine, as shown in FIG.

When the injection force is set to 1200 kg/d, the difference in variation in actual measured values is approximately 83 kg/cd, and the degree of variation is approximately 7%.
It is. Further, when the injection force is set to 2900 kg/cIl, the difference in the variation in the actual measured values is about 250 kg/d, which is about 9%, and the difference in variation becomes larger as the injection force increases.

In contrast, the injection molding machine of the present invention performs pressure feedback control as described above.

As shown in Figure 19, the injection force is 1200 kg/cn.
When set to f, the difference in the variation in actual measured values is only 14k.
The degree of variation is about 1.1% at about g/cJ. Further, when the injection force is set to 2900 kg/cJ, the difference in variation in the actual measured values is only about 30 kg/10 J, and the degree of variation is about 1%. As is clear from these results, even when the injection force becomes high, the injection molding machine according to the present invention exhibits small variations in injection force, proving that it is a highly reliable injection molding machine.

[Effects of the Invention] As described above, the present invention provides an inclination Ir that is applied to the drive system of the piston means during the movement of the piston! A sensor such as an injection reaction force sensor is installed to detect the resin pressure in the i-chamber, and in order to maintain the resin pressure in the injection chamber constant during charging,
The retraction speed of the piston means is held constant, and the supply speed of molten resin by the resin supply means is feedback-controlled based on a resin pressure detection signal from the sensor.

In an injection molding machine, it is very important to keep the charge pressure in the injection chamber constant in order to uniformly plasticize the resin. For this purpose, the retraction speed of the plunger is adjusted by keeping the rotational speed of the charging motor constant and controlling the rotational speed of the injection servo motor based on the detection signal from the injection reaction force sensor. It is conceivable to keep the charge pressure constant.

However, with this configuration, the range in which the retraction speed of the plunger can be adjusted is extremely narrow, making it impossible to properly control the plunger and making it difficult to maintain the charge pressure constant.

In this respect, the present invention has a control system as described above!
glIv11 The retraction speed of the plunger, which has an extremely narrow possible range, is kept constant, and the rotation speed of the resin supply means such as a screw is adjusted based on the detection signal from the sensor, making it easy to control and constantly charging. The pressure can be kept constant, allowing for more precise molding.

[Brief explanation of drawings]

1 to 19 are for explaining an injection molding machine according to an embodiment of the present invention. A front view of the display panel section, FIGS. 3 and 4 are a plan view and a front view showing the schematic structure of the injection molding machine, FIG. 5 is a cross-sectional view of the vicinity of the injection screw, and FIG. 6 is a cross-section of the vicinity of the slide chamber. Figure 7 is a sectional view taken along the line 1-I in Figure 6, Figure 8 is a plan view of the vicinity of the slide chamber, Figure 9 is a sectional view of the vicinity of the plunger tip, Figures 10 and 11 are mold clamping. Fig. 12 is a perspective view of the teaching pendant, Fig. 13 is a sectional view of the main part at the time of completion of the pressure holding process, Fig. 1
Figure 4 is a sectional view of main parts showing the operation after the pressure holding process is completed, and Figure 15
The figure is a front view showing the mold opening state of the fJ1 clamping part, FIG. 16 is a characteristic diagram showing the relationship between the rotation angle of the crankshaft and the moving speed of the moving die plate, and FIG. 17 is a block diagram of the servo motor control system. Fig. 18 is a pressure holding pattern diagram, and Figs. 19 and 20 are injection force characteristic diagrams of the injection molding machine of the present invention.
...Injection servo motor, 19...Fixed die plate. 20...Moving die plate, 24...
Servo motor for opening and closing the mold, 26... Heating tube, 27
...screw, 37 ... cylinder part, 38 ... injection chamber. 39...Passage, 44...Plunger,
45... radial hole, 46... axial hole,
47... Ball, 49... Holder arm, 50... Injection bar, 51... Injection reaction force sensor, 52... Drive body, 53 ...Threaded cylinder body, 58 ... Nozzle, 66 ... Crank arm, 67 ... Crankshaft, 68 ... Eccentric shaft part, 82... Molten resin, 87... Holding pressure setting device, 88... Control unit main body.

Claims (6)

[Claims] (1) A heating cylinder, an injection nozzle arranged at the tip side of the heating cylinder, a resin supply means for supplying molten resin to an injection chamber provided at the tip of the heating cylinder, and moving in the injection direction. a piston means having a stop valve mechanism that closes when the piston moves and opens when the piston moves in the backward direction, and injects the molten resin supplied to the injection chamber into the cavity through the injection nozzle; A sensor is provided to detect the resin pressure in the injection chamber when the piston moves, and in order to keep the resin pressure in the injection chamber constant during charging, the retraction speed of the piston means is kept constant, and the resin pressure from the sensor is An injection molding machine characterized in that the injection molding machine is configured to feedback control the supply speed of the molten resin by the resin supply means based on the detection signal. (2) An injection molding machine according to claim (1), wherein the resin supply means is a screw that rotates in one direction and whose rotation speed can be adjusted. (3) An injection molding machine according to claim (1), wherein the drive source for the screw is a servo motor. (4) Claim (1), characterized in that the piston means has a plunger that reciprocates at the rear of the injection nozzle, and the plunger is equipped with the stop valve mechanism. Injection molding machine. (5) Claim (1), characterized in that the piston means has a plunger that reciprocates at the rear of the injection nozzle, and the stroke length of the plunger is adjustable. Injection molding machine. (6) Claim (1), characterized in that the piston means has a plunger that reciprocates at the rear of the injection nozzle, and a holder arm that supports the plunger and reciprocates together. Injection molding machine.