JP7297818B2 - Injection molding machine and injection molding method - Google Patents

Description

The present invention relates to an injection molding machine and an injection molding method comprising an injection device that rotates a screw in a heating cylinder to plasticize a molding material and advances the screw to inject the plasticized resin.

Conventionally, a plasticizing device performs a plasticizing process by rotating a built-in screw to plasticize the input molding material, and a built-in plunger moves forward to inject and fill the plasticized resin from the injection nozzle into the mold. A pre-plastic injection molding machine equipped with an injection device for performing an injection process is known, and as this type of pre-plastic injection molding machine, for example, the pre-plastic injection molding machines disclosed in Patent Documents 1 and 2 are known. ing.

The preplasticating injection molding machine of Patent Document 1 rotates a screw contained in a plasticizing cylinder to plasticize and melt a molding material, and charges the injection cylinder with the molten resin through a non-return valve in an open state. In particular, when the plunger reaches a predetermined measurement end position during measurement, the rotation of the screw is stopped and the rotation amount and rotation speed of the screw are adjusted in advance. After that, the check valve provided between the plasticizing cylinder and the injection cylinder is closed. In addition, the pre-plasticizer type injection molding machine of Patent Document 2 has an injection cylinder with a plunger and a plasticizing cylinder with a plasticizing screw having a check valve at the tip that can rotate and move back and forth. A screw moving means and a rotating motor are provided at the rear of the plasticizing cylinder, and the backflow prevention valve is opened and closed by moving the screw back and forth by the screw moving means. It is the one that was made.

JP-A-2004-255588 JP-A-11-207794

However, the conventional injection molding machine (preplastic injection molding machine) described above has the following problems to be solved.

First, since the plasticizing device and the injection device are configured as independent separate unit devices and connected through a resin path, there is an advantage that the plasticizing process and the injection process can be performed as independent dedicated devices, respectively. A configuration in which an injection device and a plasticization device are installed side by side, specifically, the injection device is installed horizontally, and the plasticization device is tilted horizontally or downward to the front, so that the upper end of the injection device is in a two-stage configuration. often installed. As a result, the injection molding machine as a whole becomes large, requires a space in the height direction when installed, and causes an increase in oppressiveness and intimidation, as well as an increase in the cost of the entire injection molding machine. Moreover, since the resin path and the like have a complicated structure, maintenance and cleaning (replacement of resin) are difficult.

Secondly, when producing molded products by various injection molding machines such as pre-plastic injection molding machines, plasticization conditions such as resin temperature and injection conditions such as injection speed are usually matched to the type of molded product. Molding is performed by setting various molding conditions including also exist. For example, molding using recycled pellet materials that tend to have uneven pellet shapes compared to ordinary pellets due to the inclusion of crushed materials, etc. Molded products with a large injection volume that require plasticization of a large volume at one time are likely to cause molding defects and a decrease in the yield rate (rate of non-defective products). For this reason, conventionally, it has been dealt with by setting highly accurate settings for various molding conditions and stabilizing control. However, even if such measures are taken sufficiently, a considerable number of molding defects occur at actual production sites, and the specific cause of defects is not always known. More than a few, there was a limit to ensuring a high yield rate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection molding machine and an injection molding method that solve the problems existing in the background art.

In order to solve the above problems, the injection molding machine M according to the present invention has the function of rotating the screw 3 incorporated in the heating cylinder 2 by the rotation drive mechanism 4 and plasticizing the molding material charged from the hopper 5. and an injection device Mi having a function of advancing the screw 3 by the advance/retreat drive mechanism 6 and injecting the plasticized resin R from the nozzle 7 provided at the tip of the heating cylinder 2. An injection cylinder 9 having an injection nozzle 8 at its tip is disposed axially forward Fsf of the nozzle portion 7, and a mold injection portion configured as a plunger portion 10 for inserting the nozzle portion 7 into the injection cylinder 9. Ms, a valve function part 11 that opens and closes a resin passage 10r provided inside the plunger part 10, an injection device moving mechanism part 12 that moves the injection device Mi in the advancing/retreating direction Fs, a rotation driving mechanism part 4, and an advancing/retreating driving mechanism part. 6. At least the valve function part 11 and the injection device moving mechanism part 12 are driven and controlled, and after the plasticization process is performed, the resin present in front of the screw 3 is A molding machine controller 13 is provided for performing a reflux process for causing a predetermined amount of R to circulate rearward from the front end position of the screw 3 .

In this case, according to a preferred aspect of the invention, the injection device moving mechanism section 12 includes a movement drive section 14 that moves the injection device Mi in the advancing/retreating direction Fs, and a guide mechanism section 15 that guides the injection device Mi in the advancing/retreating direction Fs. can be configured with At this time, the movement driving section 14 can be configured to include an internal hollow piston section 14p covering the rear end section Mir of the injection device Mi and a pressurizing cylinder section 14c accommodating the piston section 14p. On the other hand, the guide mechanism portion 15 includes at least one rail slider portion 16s, 16s provided at the lower end of the injection device Mi and at least one guide rail portion 16r, 16r for slidably supporting the rail slider portions 16s, 16s. In addition to being constituted by the rail mechanism portions 16, 16, the guide mechanism portion 15 is provided integrally with a pair of tie rods 17t, 17t arranged at left and right separated positions with respect to the injection device Mi. and rod mechanism portions 17, 17 having rod slider portions 17m, 17m slidably moved along the tie rods 17t, 17t. The valve function unit 11 can be configured to include a shutoff valve 11v that opens and closes the resin passage 10r, and a valve driving mechanism 11d that drives the shutoff valve 11v to open and close. On the other hand, the volume Ah of the heating cylinder 2 for accumulating the plasticized resin R can be selected to be 0.3 to 3 times the volume Ac of the injection cylinder 9 .

On the other hand, in the injection molding method according to the present invention, in order to solve the above-described problems, the screw 3 incorporated in the heating cylinder 2 is rotated by the rotation drive mechanism 4, and the molding material charged from the hopper 5 is plasticized. At the same time, an injection molding method using an injection device Mi in which the screw 3 is advanced by the forward/backward drive mechanism 6 and the plasticized resin R is injected from the nozzle 7 provided at the tip of the heating cylinder 2. an injection cylinder 9 having an injection nozzle 8 at its tip is disposed axially forward Fsf of the nozzle portion 7, and a mold injection portion Ms configured as a plunger portion 10 for inserting the nozzle portion 7 into the injection cylinder 9; , a valve function portion 11 for opening and closing the resin passage 10r provided inside the plunger portion 10, and an injection device moving mechanism portion 12 for moving the injection device Mi in the advancing and retreating direction Fs. A predetermined amount of resin R is accumulated in the mold injection part Ms through the opened valve function part 11, and then, with the valve function part 11 opened or closed, the resin R existing in front of the screw 3 A predetermined amount of the resin R into a mold C for injection molding.

In this case, according to a preferred embodiment of the invention, the reflux process (S20, S40) can be performed by rotating the screw 3 in the reverse rotation direction Fn for the set time Tn, and rotating the screw 3 with a set pressurizing force. It can also be performed by applying pressure to the front Fsf. Further, in the reflux process (S20, S40), the screw 3 is rotated to perform the plasticizing process up to the set screw stop position Xce, and then the unit reflux process is performed by advancing the screw 3 for the set time Tr. After that, the valve function part 11 is opened and the screw 3 is pressurized, whereby the plunger part 10 can be retracted to the filling completion position Xpe.

According to the injection molding machine M and the injection molding method according to the present invention, the following remarkable effects can be obtained.

(1) In the injection molding machine M, the mold injection part Ms is arranged in front of the injection device Mi in the axial direction, and the nozzle part 7 is configured (also used) as a plunger part 10 for inserting into the injection cylinder 9. The entire injection molding machine M can be made smaller and more compact while ensuring the same functions as those of a pre-plastic injection molding machine capable of independently executing the molding process and the injection process.

In particular, the space in the height direction during installation can be kept to the same level as a normal inline screw injection molding machine, and the axial length can also be kept to the minimum necessary length. It is possible to avoid the problem of increasing the intimidating feeling and to reduce the cost of the entire injection molding machine M. Moreover, maintenance and cleaning (replacement of resin) can be facilitated, for example, the resin passage can be set to the shortest distance.

(2) The injection molding method of the present invention uses such an injection molding machine M to ensure the same function as a pre-plastic injection molding machine, that is, to perform the plasticizing process for the next shot during the injection process. It is possible to secure the advantage of being able to independently execute the plasticizing process and the injection process, such as being able to perform the injection molding process optimally from the viewpoint of using the injection molding machine M.

(3) After the plasticization process, a reflux process for refluxing a predetermined amount of the resin R existing in front of the screw 3 to the rear of the front end position of the screw with the valve function part 11 opened or closed. Since (S20, S40) is performed, the re-plasticization process can be performed in the heating cylinder 2. As a result, it is possible to obtain a molten resin having a high degree of kneading and excellent homogeneity, and to reduce the number of defective products, thereby further increasing the yield rate of the final molded product.

(4) According to a preferred embodiment, when constructing the injection device moving mechanism section 12, the movement driving section 14 that moves the injection device Mi in the advancing/retreating direction Fs, and the guide mechanism section 15 that guides the injection device Mi in the advancing/retreating direction Fs. , the moving mechanism of the injection device moving mechanism section 12 can be configured by the most orthodox mechanism, so that the reliable and stable moving mechanism section 12 can be constructed.

(5) According to a preferred aspect, if the movement driving section 14 is configured to include a hollow piston section 14p covering the rear end section Mir of the injection device Mi and a pressurizing cylinder section 14c accommodating the piston section 14p, Since the pressurizing cylinder portion 14c can be configured using part of the contour shape of the rear end portion Mir of the injection device Mi, the simple movement driving portion 14 can be constructed and a high-pressure hydraulic cylinder can be configured.

(6) According to a preferred embodiment, the guide mechanism part 15 is composed of at least one rail slider part 16s, 16s provided at the lower end of the injection device Mi and at least one guide rail slidably supporting the rail slider part 16s, 16s. If configured by the rail mechanism portions 16, 16 having the portions 16r, 16r, it can be guided by the rail mechanism portions 16, 16 having the most orthodox configuration, so that even the heavy injection device Mi can be moved stably and smoothly. be able to.

(7) According to a preferred embodiment, the guide mechanism part 15 is provided integrally with a pair of tie rods 17t, 17t arranged at left and right separated positions with respect to the injection device Mi and on the left and right sides of the injection device Mi, and the tie rods 17t, 17t If the rod mechanism portions 17, 17 having the rod slider portions 17m, 17m slidably moving along the 17t are configured, it is possible to prevent the injection device Mi from shaking in the left-right direction, so that the injection device Mi can be guided. This can be performed more stably, and in particular, by combining the rail mechanisms 16, 16, the most desirable form of the guide mechanism 15 can be constructed.

(8) According to a preferred embodiment, when constructing the valve function unit 11, if the shutoff valve 11v for opening and closing the resin passage 10r and the valve drive mechanism unit 11d for opening and closing the shutoff valve 11v are provided, When the drive system of the injection device Mi is composed of a hydraulic drive section, the hydraulic drive section can be used as a drive source for the valve drive mechanism section 11d, so that the control of the valve function section 11 can be simplified and ensured. At the same time, the simplification of the structure can contribute to speeding up the opening/closing operation of the shutoff valve 11v.

(9) According to a preferred embodiment, in the relationship between the heating cylinder 2 and the injection cylinder 9, the volume Ah for accumulating the plasticized resin R in the heating cylinder 2 is 0.3- It can be selected three times. That is, in an in-line screw type injection molding machine or the like, the relationship between the volume Ah and the volume Ac needs to be set within a certain magnification range, but in the injection molding machine M according to the present invention, the magnification range can be set larger. can. As a result, it is possible to satisfactorily perform the molding process from a large-sized molded product to a small-sized molded product (ultra-small molded product), so that the injection molding machine M can be provided with high versatility.

(10) According to a preferred embodiment, when the reflux process (S20, S40) is performed, the screw 3 is rotated in the reverse rotation direction Fn for the set time Tn, so that the pressure in the reflux direction can be reduced. Therefore, the reflux process can be performed quickly, and the reflux time and the reflux amount can be easily adjusted by variably controlling the rotation speed.

(11) According to a preferred embodiment, when performing the reflux process (S20, S40), if the screw 3 is pressurized forward Fsf with a set pressurizing force, the resin R can be refluxed by the simplest method. This can contribute to simplification of implementation and simplification of control.

(12) According to a preferred embodiment, when the reflux process (S20, S40) is performed, the screw 3 is rotated to perform the plasticizing process to the set screw stop position Xce, and then the screw 3 is advanced by the set time Tr. The unit reflux process is performed a set number of times N, and thereafter, the valve function part 11 is opened and the screw 3 is pressurized to retract the plunger part 10 to the filling completion position Xpe. Since it can be performed for the set number of times N, it is possible to obtain a plasticized resin with a higher degree of kneading and excellent homogeneity, and to realize optimization of the reflux treatment that matches the type and characteristics of the resin.

1 is a partial cross-sectional side view of an injection molding machine according to a preferred embodiment of the present invention; A partial cross-sectional plan view of an injection device in the same injection molding machine, XX line cross-sectional view in FIG. 1 in the same injection molding machine, Extracted and enlarged configuration diagram of the valve function part in the same injection molding machine, A flow chart showing the molding process based on the injection molding method by the basic operation (normal mode) of the same injection molding machine in order, Schematic diagram showing the state of the injection molding machine in the flowchart, A subroutine flowchart showing the detailed processing steps of the reflux treatment step in the standard reflux mode in the same flowchart; A schematic diagram showing the state of the injection molding machine in the same subroutine flow chart, A subroutine flow chart showing detailed processing steps of other reflux processing steps in the same flow chart, A schematic diagram showing the state of the injection molding machine in the same subroutine flow chart,

Next, preferred embodiments according to the present invention will be presented and explained in detail based on the drawings.

First, the configuration of an injection molding machine M according to this embodiment will be specifically described with reference to FIGS. 1 to 4. FIG.

As shown in FIGS. 1 and 2, the injection molding machine M is provided with a flat molding machine bed Mo, and on the right upper surface of the molding machine bed Mo, there is a movable bed in which an injection device Mi and a mold injection section Ms are arranged. A mold clamping device Mc is provided on the left side of the molding machine bed Mo.

In this case, the injection device Mi has a configuration similar to that of a typical inline screw injection molding machine. That is, as a basic configuration, the screw 3 incorporated in the heating cylinder 2 is rotated by the rotation drive mechanism 4 to plasticize the molding material charged from the hopper 5, and the plasticized resin R is placed in front of the screw 3. and a function of injecting the plasticized resin R from a nozzle portion 7 provided at the tip of the heating cylinder 2 by advancing the screw 3 by the forward/backward drive mechanism portion 6 .

Therefore, as shown in FIG. 2, the rear end of the screw 3 is fixed to the front end of the screw drive ram 22 that constitutes the advance/retreat drive mechanism 6, and the rear end of the screw drive ram 22 is connected to the rotation drive mechanism. 4, the tip end side of the rotation output shaft of the oil motor 21 is connected by a spline method. In this case, the rear portion of the screw 3 is covered with a hollow housing portion 23, and a stationary platen 24 is fixed to the rear end of the housing portion 23, and the front end of the oil motor 21 is attached to the stationary platen 24. As a result, by driving and controlling the oil motor 21, the screw 3 is rotated in the forward rotation direction (plasticizing direction) Fm (see FIG. 6(b)) or the reverse rotation direction Fn (see FIG. 8 ( a) can be rotated to ). On the other hand, by controlling the driving of the screw driving ram 22, the screw 3 can be moved in the forward direction Fsf, and back pressure can be applied in the backward direction. 25 denotes a band heater attached to the outer peripheral surface of the heating cylinder 2, and 26 denotes a nozzle touch cylinder for moving the movable bed Mom.

Next, the configuration of the main part of the injection molding machine M according to the present invention will be described. First, as shown in FIGS. 1 to 3, the injection device Mi is provided with an injection device moving mechanism 12 for moving the injection device Mi in the advancing/retreating direction Fs. The injection device moving mechanism section 12 includes a movement drive section 14 that moves the injection device Mi in the advancing/retreating direction Fs, and a guide mechanism section 15 that guides the injection device Mi in the advancing/retreating direction Fs. As a result, the moving mechanism of the injection device moving mechanism section 12 can be configured by the most orthodox mechanism, so that the reliable and stable moving mechanism section 12 can be constructed.

In this case, as shown in FIG. 2, the movement driving section 14 is configured with a hollow piston section 14p covering the rear end section Mir of the injection device Mi and a pressurizing cylinder section 14c accommodating the piston section 14p. . That is, a piston rod body 14pr formed in a cylindrical shape and serving as a motor cover for covering the oil motor 21 is provided. are integrally formed to form a piston portion 14p, and the piston portion 14p is housed in a cylindrical cylinder portion 14c.

As a result, a single-rod pressurizing drive cylinder 14o in which the front end side of the piston rod body 14pr protrudes forward from the cylinder portion 14c is formed, and the movement drive portion 14 using this pressurizing drive cylinder is formed. The lower end surface of the pressure driving cylinder 14o is fixed to the rear end portion of the movable bed Mom as shown in FIG. If such a movement driving section 14 is provided, a portion of the contour shape of the rear end portion Mir of the injection device Mi can be used to configure the pressurizing driving cylinder 14o, so that a simple movement driving section 14 can be constructed. , can constitute a high-pressure hydraulic cylinder.

Further, the guide mechanism portion 15 includes rail mechanism portions 16, 16 arranged at the lower end and rod mechanism portions 17, 17 arranged at both sides. The rail mechanism sections 16, 16 include at least one rail slider section 16s, 16s provided at the lower end of the injection device Mi and at least one guide rail section 16r, 16r for slidably supporting the rail slider sections 16s, 16s. . In this case, a support block 27 for supporting the injection device Mi is integrally provided at an intermediate position in the front-rear direction of the injection device Mi, that is, at the housing portion 23 described above. As shown in FIG. 3, a pair of left and right rail slider portions 16s, 16s are provided on the lower surface of the support block 27, and a pair of left and right guide rail portions 16r, 16r are provided on the upper surface of the movable bed Mom. Thereby, the rail slider portions 16s, 16s are slidably supported on the guide rail portions 16r, 16r. If the guide mechanism section 15 is configured in this way, it can be guided by the rail mechanism sections 16, 16 having the most orthodox configuration, so that even the heavy injection device Mi can be moved stably and smoothly.

Furthermore, the rod mechanism portions 17, 17 are integrally provided on the left and right sides of the injection device Mi with a pair of tie rods 17t, 17t fixed at left and right side positions separated from the injection device Mi, and along the tie rods 17t, 17t. It has rod slider parts 17m, 17m that move slidably. In this case, as shown in FIG. 2, a pair of rod support portions 28p and 28q formed in the form of bearings are fixed to the left and right sides of the pressurizing drive cylinder 14o. is fixed. As a result, a pair of rod support portions 29p, 29q formed in the form of bearings are fixed to the left and right of the cylinder support portion 29, and a separately prepared rod support portion 28p, 28q is provided between the pair of rod support portions 28p, 28q and the pair of rod support portions 29p, 29q. are fixed by a pair of tie rods 17t, 17t. A pair of left and right rod slider portions 17m, 17m provided integrally with the aforementioned support block 27 in the injection device Mi are slidably engaged with the respective tie rods 17t, 17t. With this configuration, it is possible to prevent the injection device Mi from moving in the horizontal direction, so that the guide function for the injection device Mi can be performed more stably. Thus, the most desirable form of the guide mechanism section 15 can be constructed.

On the other hand, as shown in FIG. 1, an injection cylinder 9 is arranged in front Fsf of the nozzle portion 7 in the axial direction. In this case, the cylinder support portion 29 is fixed to the upper surface of the movable bed Mom, and the rear end surface of the injection cylinder 9 is fixed to this cylinder support portion 29 . Further, the front end of the injection cylinder 9 is provided with an injection nozzle 8 whose tip nozzle port contacts the mold C. As shown in FIG. A shut-off nozzle type may be used for this injection nozzle 8, or a type in which a shut-off valve 11vs is built in the middle position of the injection nozzle 8 may be used.

Regarding the relationship between the heating cylinder 2 and the injection cylinder 9, when the volume Ah for accumulating the plasticized resin R in the heating cylinder 2 is 0.3 to 3 times the volume Ac of the injection cylinder 9, can be selected. That is, in an in-line screw type injection molding machine or the like, the relationship between the volume Ah and the volume Ac needs to be set within a certain magnification range, but in the injection molding machine M according to the present invention, the magnification range can be set larger. can. In this case, the lower limit of 0.3 times is a value that considers the operation timing of the shut-off valve, the molding cycle, and the like, and the upper limit of 3 times is a value with a margin that considers the amount of reflux. This means that it is possible to satisfactorily mold from a large molded product to a small molded product (ultra-small molded product), and the injection molding machine M can be provided with high versatility.

Further, the nozzle portion 7 is configured as a plunger portion 10 inserted from the rear end port of the injection cylinder 9 into the inside of the cylinder. Therefore, the plunger portion 10 also serves as the nozzle portion 7, and the nozzle portion 7 also serves as the plunger portion 10. The plunger portion 10 and the injection cylinder 9 constitute the mold injection portion Ms. As a result, the resin R on the heating cylinder 2 side is accommodated inside the injection cylinder 9 through the resin passage 10r provided inside the plunger portion 10, and by advancing the plunger portion 10, the resin R inside the injection cylinder 9 is can be injected into the mold C through the injection nozzle 8.

In addition, the injection molding machine M is provided with a valve function section 11 that opens and closes a resin passage 10r provided inside the plunger section 10, as shown in FIG. In the illustrated case, the valve function unit 11 includes a shutoff valve 11v for opening and closing the resin passage 10r, and a valve drive mechanism unit 11d for opening and closing the shutoff valve 11v. The shut-off valve 11v can be disposed at an intermediate position of the plunger portion 10 or between the rear end of the plunger portion 10 and the heating cylinder 2, and the resin passage 10r can be closed by rotating the cylindrical valve body 11vm by 90 degrees. can be opened and closed. For this reason, the valve driving mechanism portion 11d includes a forward/backward drive cylinder 11dc whose rear end is connected to the support block 27 via a rotating portion, and a forward end of a drive rod 11dr projecting forward from the forward/backward drive cylinder 11dc and a valve. It comprises a connecting mechanism 11mj that connects the bodies 11vm.

As a result, as shown in FIG. 4, by controlling the driving of the forward/backward driving cylinder 11dc and displacing the driving rod 11dr in the retracting direction Fp, the valve body 11vm can be switched to the closing side and the driving rod 11dr can be projected. The valve body 11vm can be switched to the open side by turning 90 degrees in the direction. With this configuration, when the drive system of the injection device Mi is composed of the hydraulic drive section, the hydraulic drive section can be used as the drive source of the valve drive mechanism section 11d. The simplification and reliability can be achieved, and the simplification of the structure can contribute to speeding up the opening/closing operation of the shutoff valve 11v.

On the other hand, as shown in FIG. A hydraulic drive unit 31 comprising a hydraulic circuit and various valves is provided. The hydraulic drive unit 31 includes a screw drive ram 22 (advance/retreat drive mechanism 6), an oil motor 21 (rotational drive mechanism 4), and a hydraulic cylinder 14o. (Movement drive unit 14) and advance/retreat drive cylinder 11dc (valve drive mechanism unit 11d) are connected, respectively, and nozzle touch cylinder 26 shown in FIG. 1 is also connected. A molding machine controller 13 for giving various control commands is connected to the hydraulic drive unit 31, and various position information, time information, pressure information and switching information in the injection molding machine M are sent to the molding machine controller 13. A sensor group 32 for detecting such as is connected. As a result, the molding machine controller 13 can drive and control at least the rotation drive mechanism section 4 , the advance/retreat drive mechanism section 6 , the valve function section 11 and the injection device movement mechanism section 12 .

Next, a molding method using the injection molding machine M configured as described above, that is, an injection molding method according to the present embodiment will be described with reference to FIGS. 5 to 10. FIG.

The injection molding method according to the present embodiment includes, in addition to the basic injection molding method in the normal mode, injection molding methods in various reflux modes including a reflux treatment step in which the resin R is repeatedly plasticized two or more times. can be implemented.

First, the injection molding method in the normal mode will be described with reference to FIGS. 6(a)-(c) and according to the flowchart shown in FIG.

FIG. 6(a) shows the state of the injection molding machine M in which the resin R does not exist. That is, the tip of the injection nozzle 8 touches the clamped mold C, the plunger part 10 is at the most advanced position of the injection cylinder 9, and the tip of the screw 3 is at the most advanced position of the heating cylinder 2. indicates a stopped state. Furthermore, the shut-off valve 11v is switched to an open state. When a shut-off nozzle is used for the injection nozzle 8, it is controlled to be in a shut-off state, and as illustrated in FIG. switches to the closed side.

In the normal mode, first, the plasticizing step shown in FIG. 6(b) is executed (step S1). In the plasticizing process, since the shut-off valve 11v is switched to the open side, the screw 3 is controlled to rotate in the forward rotation direction Fm, which is the plasticizing direction, by driving and controlling the oil motor 21 . Thereby, the molding material (pellet material) put into the heating cylinder 2 from the hopper 5 is plasticized by the heating cylinder 2 and the screw 3 . Further, the plasticized resin R passes through the open shutoff valve 11v and further through the resin passage 10r of the plunger portion 10, and accumulates in the injection cylinder 9. As shown in FIG.

Then, when the plasticizing process progresses and the resin R is accumulated inside the injection cylinder 9, the plunger portion 10 and the injection device Mi move backward in the direction of the arrow Fb according to the amount of the accumulated resin. At this time, a predetermined back pressure is applied to the screw 3 by controlling the driving of the pressure driving cylinder 14o. After that, when the plunger portion 10 reaches the set plunger stop position Xpm, the plasticizing process is terminated. This state is the state of FIG. 6(b).

When the plasticizing process is completed, it is confirmed that the mold clamping process is completed (step S2), and the shutoff valve 11v is switched to the closed side (steps S3 and S4). That is, in the injection molding method in the normal mode, since the reflux process is not performed, the shut-off valve 11v is quickly switched to the closed side after the plasticizing process is completed, and the shut-off valve 11vs is controlled to be switched to the open side. After that, an injection process is executed (step S5). In the injection process, the pressurized hydraulic cylinder 14o is driven and controlled to move the entire injection device Mi forward in the direction of the arrow Fi shown in FIG. 6(c), that is, to the set forward target position Xpi. As a result, the plunger portion 10 moves forward from the plunger stop position Xpm to the forward target position Xpi, and injection filling of the mold C with the resin R is performed. This state is shown in FIG. 6(c).

After that, the cooling process is performed for the set cooling time Tc (step S6), and when the cooling time Tc has passed, the mold opening process is performed (step S7). Then, a molded article removing process for removing the molded article is performed (step S8), and the next mold clamping process can be performed (steps S9 and S10).

Next, with regard to the injection molding method using the standard reflux mode, that is, the reflux treatment step S20 shown in the flowchart of FIG. will be described according to the subroutine flow chart shown in .

In the standard reflux mode, the reflux process is selected in step S3 after the plasticizing step (step S1) in the flowchart of FIG. 5 is completed. It is also assumed that the state shown in FIG. 6B is present when the reflux process is selected. That is, it is in a state after the plasticizing step (step S1) in the normal mode is completed. Furthermore, in the case of the standard reflux mode, the shutoff valve 11v is kept open (step S21).

On the other hand, in the standard reflux mode, it is possible to select whether or not reverse rotation control of the screw 3 is executed. Assume now that reverse rotation control is selected (step S22). By selecting the reverse rotation control of the screw 3, it is confirmed that the molding process of the injection molding machine M is in the injection process (step S23), and the screw 3 is set as shown in FIG. Rotation is controlled in the reverse rotation direction Fn for a set time according to the rotation speed (steps S24 and S25). At this time, it is desirable to apply a predetermined forward pressure by controlling the driving of the pressure driving cylinder 14o. As a result, due to the reverse rotation of the screw 3, at least a portion of the resin R in front of the front end of the screw 3 is relatively circulated rearward of the front end of the screw 3, and the resin in the injection cylinder 9 is R is also mixed into the resin R in the heating cylinder 2 through the resin passage 10r. As a result, the plunger portion 10 moves forward by the amount of the reflux. FIG. 8A shows a state in which the resin R flows backward through the resin passage 10r in the direction of the arrow Frb, and the plunger portion 10 moves from the plunger stop position Xpm to the forward position Xpf. Further, due to the reflux treatment, the resin R forward of the front end of the screw 3 is refluxed rearward of the front end of the screw 3 and mixed with the resin R being plasticized.

In this way, when performing the reflux treatment step S20, if the screw 3 is controlled to rotate in the reverse rotation direction Fn for the set time Tn, the pressure in the reflux direction can be reduced, so that the reflux treatment can be performed quickly. By variably controlling the rotation speed, the reflux time and the reflux amount can be easily adjusted.

Then, it is confirmed that the cooling process is in progress (step S26), and the screw 3 is rotationally driven in the forward rotation direction (plasticizing direction) Fm (step S27). In this case, the rotation in the plasticizing direction is performed until the screw 3 reaches the screw stop position Xce set to the rear (step S28). Therefore, in the plasticizing treatment at this time, the resin R that is being plasticized is mixed with the resin R that has been circulated, and the circulated resin R is subjected to the re-plasticizing treatment. This state is shown in FIG. 8(b).

After that, when the screw 3 reaches the screw stop position Xce, the screw 3 is moved forward (step S29). As a result, the resin R in the heating cylinder 2 is transferred to the inside of the injection cylinder 9 through the resin passage 10r. Since the plunger portion 10 moves in the direction, the reflux processing step S20 is terminated when the plunger portion 10 reaches the filling completion position Xpe (step S30). This state is shown in FIG. 8(c).

It should be noted that if the reverse rotation control of the screw 3 is not selected in step S22, the reflux process is not performed. In this case, it is confirmed that the cooling process is still in progress (step S26), and the screw 3 is controlled to rotate for the plasticizing process described above (step S27). At this time, the rotation in the plasticizing direction is performed until the screw 3 reaches the screw stop position Xce set in the rearward direction. When the part 10 reaches the filling completion position Xpe, the reflux treatment step S20 is ended (steps S28, S29, S30).

Thus, in the standard reflux mode, since the reflux treatment step S20 is provided, a portion of the resin R forward of the front end of the screw 3 is moved backward of the front end of the screw 3 by reverse rotation control of the screw 3. Reflux. As a result, the recirculated resin R is plasticized again by the rotation (plasticization) of the screw 3, so that a molten resin having a high degree of kneading and excellent homogeneity can be obtained. By reducing non-defective products, the yield rate of final molded products can be further increased. In particular, if the screw 3 is pressurized with a predetermined pressurizing force to control the reverse rotation, the pressure in the reflux direction can be reduced, so that the reflux process can be performed quickly and the rotation speed can be variably controlled. Therefore, the reflux time and the reflux amount can be easily adjusted.

As described above, since the plasticizing process including the reflux process is completed, it is possible to confirm that the mold clamping process has been completed (step S2), and perform post-processing including the injection process in the normal mode shown in FIG. .

Next, referring to FIGS. 10(a) and 10(b), the flow chart shown in FIG. 5 and FIG. will be described according to the subroutine flow chart shown in .

In this case, after the plasticizing step (step S1) in the flowchart of FIG. 5 is completed, the reflux treatment is not selected in step S3, and the shut-off valve 11v is switched to the closed side, and then the reflux treatment step S40 is performed. Give an example.

In this reflux treatment step S40, first, rotation control for plasticizing the screw 3 is performed (step S41). As a result, the screw 3 retreats and the plasticized resin R accumulates in front of the screw 3 . Further, as the resin R accumulates, the screw 3 retreats in the direction of the arrow Fbs. This state is shown in FIG. The rotation control for this plasticizing process is performed until the screw 3 reaches the set stop position Xce (see FIG. 8(b)) (step S42).

Then, after that, a reflux process is performed (step S43). In this case, the return process drives and controls the screw drive ram 22 to move the screw 3 forward, that is, drives and controls the pressure drive cylinder 14o to pressurize the screw 3 with a predetermined pressure for a set time. (Steps S44, S45). As a result, the screw 3 moves to a predetermined forward position, for example, a forward position Xcf shown in FIG. 10(b). As a result, at least a portion of the resin R in front of the front end of the screw 3 relatively moves rearward from the front end of the screw 3 due to the action of the pressurizing force. For this reason, it is desirable that the outer diameter of the screw head of the screw 3 is previously cut to a small diameter or formed with a plurality of grooves so that the resin R can be easily circulated by the applied pressure. In this way, if the screw 3 is pressurized forward Fsf with a set pressurizing force, the resin R can be circulated by the simplest method, which facilitates implementation and control. can contribute.

Further, in this case, steps S41 to S45 are unit return processing, so this unit return processing is repeatedly performed for the preset number of times N (step S46). When the unit reflux process has been completed for the set number of times N, it is confirmed that the molding process of the injection molding machine M is in the cooling process (step S47), the shutoff valve 11v is switched to the open side (step S48), and the screw is 3 is moved forward (step S49). As a result, the resin R in the heating cylinder 2 is transferred to the inside of the injection cylinder 9 through the resin passage 10r, and along with this, the plunger portion 10 (injection device Mi) moves backward in the direction of the arrow Fb. . As a result, when the plunger portion 10 reaches the filling completion position Xpe (see FIG. 10(b)), the reflux treatment step 40 ends (step S50).

In this way, after the plasticizing process is performed up to the set screw stop position Xce by rotating the screw 3, the unit reflux process is performed by advancing the screw 3 by the set time Tr for the set number of times N, and then the valve If the plunger portion 10 is retracted to the filling completion position Xpe by opening the function portion 11 and pressurizing the screw 3, the unit reflux process can be performed for the set number of times N, so that the degree of kneading is higher. Therefore, it is possible to obtain a plasticized resin excellent in homogeneity, and to realize optimization of the reflux treatment that matches the type and characteristics of the resin.

If the reflux process is not selected in step S43, the rotation control for the plasticizing process (step S41) causes the screw 3 to first reach the stop position Xce (see FIG. 10(b)). If so, it is confirmed that the cooling process is still in progress (step S47), and the shutoff valve 11v is switched to the open side (step S48). Then, the screw 3 is moved forward (step S49). As a result, the resin R in the heating cylinder 2 is transferred to the inside of the injection cylinder 9 through the resin passage 10r. When the part 10 reaches the filling completion position Xpe, the reflux processing step S40 ends (step S50).

In this way, the plasticizing process is performed, the shut-off valve 11v is closed, and the screw 3 is rotated to perform the plasticizing process up to the set screw stop position Xce. By moving the part 10 forward to the filling completion position Xpe, the effective strokes of the heating cylinder 2 and the injection cylinder 9 can be utilized to the maximum, so that the most efficient and efficient molding process can be performed.

Therefore, according to the injection molding machine M (injection molding method) according to the present embodiment, as a basic method, the injection cylinder 9 having the injection nozzle 8 at the front end Fsf of the nozzle portion 7 in the axial direction is and a mold injection part Ms configured as a plunger part 10 for inserting the nozzle part 7 into the injection cylinder 9; a valve function part 11 for opening and closing a resin passage 10r provided inside the plunger part 10; An injection device moving mechanism 12 is provided to move the device Mi in the advancing/retreating direction Fs. During molding, a predetermined amount of resin R plasticized by the injection device Mi is injected into the mold injection portion Ms through the opened valve function portion 11. After that, the valve function unit 11 is closed, and the injection device moving mechanism 12 advances the injection device Mi to perform the injection molding process in which the resin R is injected from the injection nozzle 8 into the mold C. The molding machine M can be configured (also used) as a plunger section 10 for inserting the nozzle section 7 into the injection cylinder 9 while arranging the mold injection section Ms in front of the injection device Mi in the axial direction. As a result, it is possible to reduce the overall size of the injection molding machine M while ensuring the same functions as those of a preplasticating injection molding machine capable of independently executing the plasticizing process and the injection process. In particular, the space in the height direction during installation can be kept to the same level as a normal inline screw injection molding machine, and the axial length can also be kept to the minimum necessary length. It is possible to avoid the problem of increasing the intimidating feeling and to reduce the cost of the entire injection molding machine M. Moreover, maintenance and cleaning (replacement of resin) can be facilitated, for example, the resin passage can be set to the shortest distance. In particular, according to the injection molding method according to the present embodiment, by using such an injection molding machine M, the same function as that of a pre-plastic injection molding machine is ensured, that is, the next shot is plasticized during the injection process. The plasticizing process and the injection process can be performed independently, and the optimum injection molding process can be performed from the viewpoint of using the injection molding machine M.

Although the preferred embodiments have been described in detail above, the present invention is not limited to such embodiments, and detailed configurations, shapes, materials, quantities, numerical values, etc. do not deviate from the gist of the present invention. Any change, addition, or deletion can be made within the range.

For example, the injection device moving mechanism section 12 includes the movement drive section 14 that moves the injection device Mi in the advancing/retreating direction Fs, and the guide mechanism section 15 that guides the injection device Mi in the advancing/retreating direction Fs. Any other mechanism can be substituted as long as it has a function of moving Mi in the advancing/retreating direction Fs. Moreover, although the pair of left and right rail mechanism portions 16, 16 are illustrated, the use of a single rail mechanism portion 16 is not excluded when used in combination with the rod mechanism portions 17, 17. FIG. Further, the valve function unit 11 has been shown to include the shutoff valve 11v for opening and closing the resin passage 10r and the valve driving mechanism 11d for opening and closing the shutoff valve 11v. It can be replaced by other various valve function units 11 as long as they have the function of On the other hand, two different aspects of the reflux processing steps S20 and S40 have been illustrated as the reflux mode, but the execution timing and detailed processing can be replaced with other various aspects as long as the reflux processing can be realized. . Although a hydraulic drive unit is exemplified as a drive system, it can be applied to an injection molding machine using an arbitrary drive source such as an electric drive, a hybrid system combining an electric drive and a hydraulic system, and a pneumatic system.

INDUSTRIAL APPLICABILITY The injection molding machine and injection molding method according to the present invention can be used to mold molded articles using various resins, ranging from large molded articles to small molded articles (ultra-small molded articles).

M: injection molding machine, Mi: injection device, Mir: rear end of injection device, Ms: mold injection part, 2: heating cylinder, 3: screw, 4: rotation drive mechanism part, 5: hopper, 6: advancing and retreating Drive Mechanism Part 7: Nozzle Part 8: Injection Nozzle 9: Injection Cylinder 10: Plunger Part 10r: Resin Passage 11: Valve Function Part 11v: Shutoff Valve 11d: Valve Drive Mechanism Part 12: Injection device moving mechanism part, 13: molding machine controller, 14: movement driving part, 14p: piston part, 14c: pressure cylinder part, 15: guide mechanism part, 16: rail mechanism part, 16s: rail slider part, 16r: Guide rail portion, 17: Rod mechanism portion, 17t: Tie rod, 17m: Rod slider portion, R: Resin, Fs: Retraction direction, Fsf: Forward in axial direction, Ah: Volume, Ac: Volume, C: Mold, Xce : screw stop position, Xpe: filling completion position, S20: reflux treatment process, S40: reflux treatment process, Fn: reverse rotation direction, N: set number of times

Claims (11)

The screw contained in the heating cylinder is rotated by the rotation drive mechanism to plasticize the molding material fed from the hopper. An injection molding machine comprising an injection device having a function of injecting from a nozzle portion provided at the tip of a heating cylinder, wherein an injection cylinder having an injection nozzle at the tip thereof is arranged in front of the nozzle portion in the axial direction, A mold injection part configured as a plunger part for inserting the nozzle part into the injection cylinder, a valve function part for opening and closing a resin passage provided inside the plunger part, and an injection device movement for moving the injection device in a forward and backward direction A state in which at least the mechanical section, the rotation drive mechanism section, the advance/retreat drive mechanism section, the valve function section, and the injection device movement mechanism section are driven and controlled, and the valve function section is opened after plasticization processing is performed. or a molding machine controller for performing a reflux process for refluxing a predetermined amount of resin existing in front of the screw in a closed state to the rear of the front end position of the screw. 2. The injection molding machine according to claim 1, wherein the injection device moving mechanism section includes a movement drive section for moving the injection device in the advancing and retreating direction, and a guide mechanism section for guiding the injection device in the advancing and retreating direction. . 3. The injection molding machine according to claim 2, wherein the moving drive section comprises a hollow piston section covering the rear end of the injection device and a pressurizing cylinder section accommodating the piston section. The guide mechanism section is configured by a rail mechanism section including at least one rail slider section provided at the lower end of the injection device and at least one guide rail section for slidably supporting the rail slider section. 4. The injection molding machine according to claim 2 or 3. The guide mechanism includes a pair of tie rods arranged at left and right separated positions with respect to the injection device, and a rod slider unit provided integrally on the left and right sides of the injection device and slidably moving along the tie rods. 5. The injection molding machine according to claim 2, wherein the injection molding machine comprises a rod mechanism portion. 2. The injection molding machine according to claim 1, wherein the valve function section includes a shutoff valve for opening and closing the resin passage, and a valve drive mechanism section for opening and closing the shutoff valve. 2. The injection molding machine according to claim 1, wherein said heating cylinder has a capacity of 0.3 to 3 times as large as that of said injection cylinder for accumulating plasticized resin. The screw contained in the heating cylinder is rotated by the rotation drive mechanism to plasticize the molding material fed from the hopper, and the screw is advanced by the advance/retreat drive mechanism to push the plasticized resin out of the heating cylinder. An injection molding method using an injection device that injects from a nozzle portion provided at the tip, wherein an injection cylinder having an injection nozzle at the tip is disposed in advance in front of the nozzle portion in the axial direction, and the nozzle portion into the injection cylinder, a valve function part for opening and closing a resin passage provided inside the plunger part, and an injection device moving mechanism part for moving the injection device in the advancing and retreating direction. is provided, during molding, a predetermined amount of resin plasticized by the injection device is accumulated in the mold injection part through the opened valve function part, and then the valve function part is opened or closed. In this state, a predetermined amount of the resin existing in front of the screw is circulated to the rear of the front end position of the screw. An injection molding method characterized by performing an injection molding process in which a device is moved forward to inject a resin from the injection nozzle into a mold. 9. The injection molding method according to claim 8, wherein said reflux treatment is performed by rotating said screw in reverse for a set time. 9. The injection molding method according to claim 8, wherein said reflux treatment is performed by pressurizing said screw with a pressure set forward. In the reflux process, the screw is rotated to perform a plasticizing process up to a set screw stop position, and then a unit reflux process in which the screw is advanced for a set time is performed a set number of times. 9. The injection molding method according to claim 8, wherein the plunger portion is retracted to a filling completion position by opening the portion and pressurizing the screw.

Images