JP3286027B2 - Injection molding die and injection molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold and an injection molding method for molding a thick molded product with high precision.

[0002]

2. Description of the Related Art When injection molding a thick product such as a plastic lens, there is a problem that the molding cycle time becomes long because cooling is required to prevent sinking and deformation.
As a method for solving this, a conventional method is disclosed in Japanese Patent Application Laid-Open No. 64-3642.
The injection molding method described in Japanese Patent Publication No. 1 is known. In this injection molding method, the cavity unit is clamped by a U-shaped mold clamping member, and the mold unit is heated to a temperature equal to or higher than the glass transition point to inject the molten resin. Slowly cool to temperature, then
The mold is released from the mold clamping mechanism of the molding machine while the mold clamping of the cavity unit is held by itself, and the cavity unit is cooled independently.

[0003]

In the prior art, however, the cavity unit must be once isolated from the mold clamping mechanism of the molding machine during the cooling step, and another cavity unit must be set during that time. There is a problem that it takes too much time for attachment, detachment and replacement. The present invention has been made in view of such a problem, and provides an injection mold and an injection molding method that can eliminate the need for moving, attaching, detaching, and replacing a cavity unit and can shorten a molding cycle. With the goal.

[0004]

In order to achieve the above object, an injection mold according to the present invention comprises a movable cavity unit and a fixed cavity unit which forms a cavity when one surface comes into close contact with the movable cavity unit. And, an elastic member that urges the close contact surface to be in close contact when the movable side and the fixed side of the cavity unit are in close contact with each other,
A first holding member capable of holding the fixed-side cavity unit separated from the movable-side cavity unit in the mold opening direction; and releasing the fixed-side cavity unit by releasing the first-side holding member from the fixed-side cavity unit. A second holding member that can be held on the movable-side cavity unit side, and an operation control selectively provided at the fixed-side cavity unit and at an engagement position with the first holding member or an engagement position with the second holding member. And a locking means for holding the fixed-side cavity unit when engaged with the first or second holding member. A resin flow path for distributing the molten resin injected from the resin molding nozzle is formed in each set of cavities formed by the side and fixed side cavity units. A manifold that is disposed in the flow path of the manifold, is characterized in that it comprises a and a switching means for switching the supply and cutoff of the molten resin into the cavity. Further, the injection molding method of the present invention is directed to an injection molding method of injecting a molten resin from a resin injection nozzle into a cavity after a movable platen is moved forward to a fixed platen side in an injection molding machine and mold-clamped. At least two sets of a pair of cavity units forming a cavity are arranged between the fixed-side platen and the movable-side platen, and at least one set A is self-held while at least one set B is formed. In the state where the mold is opened, each one of the cavity knits is arranged side by side on the movable side mounting plate on the movable side platen side, and is arranged side by side on the fixed side platen side facing the movable side mounting plate. The other cavity unit of the set B in the mold opened state is held against the holding member on the fixed platen side capable of holding the other cavity unit of the set AB. Tsu DOO is held, then, in a state of self-holding of the movable platen to move forward to the movable side mounting plate cavity unit A
Then, the cavity unit B in the mold opened state is clamped, and at this time, the side surfaces of the cavity units of each set are separated from each other and exposed, and the manifold is opened to the cavity of the cavity unit B in the mold opened state. The molten resin is supplied from the nozzle through the resin flow path, and after a predetermined amount is supplied, the supply of the molten resin to the cavity is cut off by the switching means provided in the flow path, and the other side of the cavity unit B is supplied. By operating the locking means operable to the engagement position for holding the holding member provided on the cavity unit and the disengagement position for releasing the holding to the disengagement position, one cavity unit and the other A set B with the cavity unit is made self-holding, and the cavity unit in the self-holding state To prevent the molten resin from being supplied to the cavity by the switching means provided in the resin flow passage of the manifold, and to hold the cavity unit A to the holding member provided in the other cavity unit. The self-holding state of the cavity unit A in the self-holding state is released by operating the locking means operable to the position and the engagement releasing position for releasing the holding to the engagement releasing position, and the other cavity unit is released. Is held by the holding member on the fixed-side platen side, and then the movable-side platen is retracted to retract the movable-side platen together with the movable-side platen while the set B is held in a self-holding state. The method is characterized in that the molded product is taken out in an opened state.

[0005]

In the above-described structure, the self-holding of the mold clamping force of the cavity unit and the mold opening of the cavity unit are performed by operating the locking means to the engaging position or the disengaging position with the holding member. The switching means provided in the manifold channel supplies the molten resin to the cavity unit in the mold-clamped state by the operation thereof, while the switching means melts the cavity unit in the self-holding state or the cavity unit in the mold-opened state with the mold clamping force. Cut off the resin supply. Therefore, by linking the operation of the switching means with the mold clamping and mold opening, molding can be performed without moving, attaching, detaching, or replacing the cavity unit.

[0006]

First Embodiment FIGS. 1 to 6 show a first embodiment of the present invention. As shown in FIG. 1, the cavity 29 for molding is formed by the close contact between the movable side cavity unit 1 and the fixed side cavity unit 2.
A plurality of movable side cavity units 1 (two in the illustrated example) are fixed in parallel to each other with a gap therebetween, and the movable side mounting plate 13 is fixed to a movable side platen 15. . On the other hand, the fixed-side cavity unit 2 includes the fixed-side holding plate 4 fixed to the fixed-side platen 17.
It is detachably attached to. In this way, the movable-side mounting plate 13 and the fixed-side holding plate 4
In the structure fixed to the molds 5 and 17, the cavity units 1 and 2 do not move in other directions except for moving integrally with them at the time of mold clamping and mold opening. Here, the fixed-side holding plate 4 is connected to the molten resin flow path 14a that sends the molten resin to the plurality of fixed-side cavity units 2 that are spaced apart from each other in the mold-clamped state, and to the fixed-side cavity units 2. A manifold (hot runner manifold) 14 having a valve device 14b as a switching means for controlling the flow of the molten resin.

FIGS. 3 to 6 show the structure of the hot runner manifold 14. FIG. The valve device 14 b
a rotatably provided in a hole 14c provided in the middle of the flow path 14a in a direction perpendicular to the flow path 14a.
a, which has a flow path 14d that can communicate with a. Reference numeral 20 denotes a motor connected to the valve device 14b to transmit a rotational driving force, and is built in the fixed-side holding plate 4. These valve devices 14b
The same number of motors 20 are provided for each of the plurality of fixed-side cavity units. The motor 20 is arranged such that the flow path 14d is 90 ° with respect to the flow path 14a.
The flow of the molten resin is interrupted by rotating the valve device 14b such that the flow of the molten resin is stopped (see FIG. 5), while the valve device 14b is rotated so that the flow path 14d is parallel to the flow path 14a. It acts to allow the flow to pass to the fixed side cavity unit 2 (see FIG. 6). In FIG. 3, reference numeral 40 denotes a resin injection nozzle which is pressed against the hot runner manifold 14.

The fixed-side cavity unit 2 includes a fixed-side mold plate 5 that is in close contact with the movable-side cavity unit 1 and a fixed-side mounting plate 9 that is detachably attached to a fixed-side platen 17 via a fixed-side holding plate 4. It has. A spring 25 is provided between the fixed-side mold plate 5 and the fixed-side mounting plate 9 as an elastic member for self-holding the mold clamping force.
The fixed-side template 5 is urged in the direction of the movable-side cavity unit 1 by the spring 25, so that a gap is generated between the fixed-side template 5 and the fixed-side mounting plate 9. The movement amount is regulated by the stop pin 24.

As shown in FIG. 2, the fixed-side mounting plate 9 has a dovetail-shaped groove 9a formed in a pair of side walls in a direction perpendicular to the mold opening direction, and has a U-shaped locking member as locking means. 11 is inserted into the groove 9a.
The lock member 11 has protrusions 11 of dimension T at its upper and lower ends.
a and the concave portions 11b having the dimension H are formed alternately. As will be described later, these convex portions 11a and concave portions 11b are used for interlocking the self-holding of the mold clamping state and the release thereof with the mold clamping and mold opening. 8 is such a lock member 11
Is an actuator that slides in a direction orthogonal to the mold opening, and is fixed to an end surface of the fixed-side mounting plate 9 in the illustrated example.

In addition to the above configuration, the fixed-side holding plate 4 and the movable-side cavity unit 1 are each provided with the fixed-side cavity unit 2 via the lock member 11 when they are engaged with the lock member 11. Hook members 3 and 12 are attached as holding members for enabling holding. The hook member (first holding member) 3 in the fixed-side holding plate 4 has a hook piece 3a extending in the mold opening direction and a slit 3b provided between the hook pieces 3a.
The hook pieces 3a and the slits 3b engage with and disengage from the convex portions 11a and the concave portions 11b of the lock member 11. Hook members (second holding members) 12 in the movable cavity unit 1 are fixed to the upper end surface and the lower end surface of the two movable cavity units 1 provided side by side. As is clear from FIG. 1, the hook member 12 fixed to the upper end surface of the lower cavity unit 1 in FIG. 1 and the hook member 12 fixed to the lower end surface of the upper cavity unit 1 in FIG. Are empty and separated. At the tip of each hook member 12, a hook piece 12a having a size slightly smaller than the size T of the projection 11a of the lock member 11 and a size H of the recess 11b of the lock member 11 are provided.
Slits 12b having a somewhat larger size are formed alternately, and engagement and disengagement with the lock member 11 are performed by the hook pieces 12a and the slits 12b.

Next, the operation of this embodiment will be described. The lower side of the two cavity units in FIG. 1 will be described as a first cavity unit, and the upper side will be described as a second cavity unit. As shown in FIG. 1, the first cavity unit previously sets the hook member 3 and the lock member 11 in the engaged state, and the second cavity unit sets the hook member 12 and the lock member 11 in the engaged state to open the mold. Keep it.
The side surface of the first cavity unit in the engaged state is exposed. After the movable platen 15 is moved forward to perform mold clamping, the molten resin is injected into the first cavity unit by switching the valve device 14b of the first cavity unit of the hot runner manifold 14. After removing the holding pressure after injection, the valve device 1 of the first cavity unit
4b is switched to shut off the molten resin in the first cavity unit. In the first cavity unit, the lock member 11 is moved by the actuator 8 in a direction orthogonal to the mold opening, and the convex portion 11a is formed into the hook piece 12a of the hook member 12 of the movable side cavity unit 1, and the concave portion 11b is formed into the slit. 12b. This allows
The hook member 12 and the lock member 11 of the movable side cavity unit 1 are engaged.

On the other hand, in the second cavity unit, the lock member 11 is moved by the actuator 8 in a direction orthogonal to the mold opening, and the convex portion 11a is inserted into the slit 12b of the hook member 12 of the movable side cavity unit 1.
The recess 11b is positioned on the hook piece 12a of the hook member 12. Thus, the engagement between the hook member 12 and the lock member 11 of the movable side cavity unit 1 is released, and the hook member 3 and the lock member 1 of the fixed side holding plate 4 are released.
1 is engaged.

When the movable platen 15 is retracted in this state, the first cavity unit moves together with the movable platen 15 with the movable cavity unit 1 and the fixed cavity unit 2 integrated. At this time, the fixed-side mold plate 5 is pressed in the direction of the movable-side cavity unit 1 by the urging force of the spring 25, so that the parting line surface (PL surface) is closed, and the mold clamping is self-held. In the second cavity unit, the parting line surface is opened so that a molded product can be taken out. Note that there is no molded product in the first time, and no removal is performed.

Next, mold clamping is performed again, and the valve device 14b of the second cavity unit of the hot runner manifold 14 is switched to inject the molten resin into the second cavity unit. After removing the holding pressure after the injection, in the second cavity unit, the valve device 14b is switched to shut off the molten resin, and the lock member 1 is actuated by the actuator 8.
The movable part 1 is moved in a direction orthogonal to the opening of the mold, so that the convex part 11a is located at the hook piece 12a of the hook member 12 of the movable side cavity unit 1, and the concave part 11b is located at the slit 12b. Thereby, the hook member 12 and the lock member 11 of the movable side cavity unit 1 are engaged.

On the other hand, in the first cavity unit, the lock member 11 is moved by the actuator 8 in a direction orthogonal to the mold opening, and the protrusion 11a is inserted into the slit 12b of the hook member 12 of the movable side cavity unit 1.
The recess 11b is positioned on the hook piece 12a. Thereby, the engagement between the hook member 12 of the movable side cavity unit 1 and the lock member 11 is released, and the hook member 3 of the fixed side holding plate 4 and the lock member 11 are engaged.

When the movable platen 15 is retracted in this state, the second cavity unit moves together with the movable platen 15 with the movable cavity unit 1 and the fixed cavity unit 2 integrated. At this time, spring 2
Since the fixed mold plate 5 is pressed toward the movable cavity unit 1 by the urging force of 5, the parting line surface is closed and the mold clamping force is self-held.

At this time, in the first cavity unit, the parting line surface is opened, and the molded product can be taken out. Thereafter, by repeating these steps,
Injection molding is performed on a plurality of cavity units alternately.

In this embodiment, the operation of the valve device 14b in the hot runner manifold 14 is linked with the mold clamping and mold opening, and the self-holding of the mold clamping force of the cavity unit and the mold clamping and mold opening are performed. Therefore, there is no need to move, detach, and replace the cavity unit, and efficient molding without loss time can be performed. Further, even when the resin internal pressure acts on the hook member 12 during self-holding of the mold clamping force of the pair of cavity units 1 and 2,
Since the compression force by the spring 25 is applied to the PL surface, the PL surface is not opened. Further, since the actuator 8 is linked with the mold clamping operation, the self-holding of the cavity units 1 and 2 can be turned ON / OFF, and automation can be performed. In addition, since the self-holding ON / OFF and the holding / holding of the cavity unit by the fixed side holding plate 4 are simultaneously switched by the mold clamping operation, there is no malfunction and the mold damage due to the malfunction can be prevented. In this case, by reducing the pitch between the convex portion 11a and the concave portion 11b of the lock member 11, the self-holding ON / OFF switching stroke can be reduced.

[0019]

Second Embodiment FIGS. 7 and 8 show a second embodiment of the present invention, wherein the same elements as those of the first embodiment are denoted by the same reference numerals and correspond to each other. In this embodiment, the two cavity units are arranged so as to face each other when the lock member 11 inserted into the fixed-side mounting plate 9 slides.
A connection hole 11c is formed in an end face of each lock member 11. An actuator 8 having an output end at both ends is attached to the fixed-side holding plate 4.
c is provided with a cylinder rod 8a to be engaged.

In such a structure, when the actuator 8 reciprocates, the left and right lock members 11 make opposite movements. That is, when the lock member 11 of one cavity unit is engaged with the hook member 3 of the fixed side holding plate 4, the lock member 11 of the other cavity unit is released from engagement with the hook member 3 of the fixed side holding plate 4. Is done.

In the above configuration, when the movable side platen 15 and the cylinder rod 8a correspond to each other to perform mold clamping and the actuator 8 is reciprocated, the reciprocating motion is also transmitted to the lock member 11, and the left and right lock members 11 Make the opposite move.

Accordingly, in this embodiment, the single actuator 8 corresponds to the two fixed-side cavity units, and the locking member 11 for self-holding and releasing the mold clamping force is moved. The number of points is reduced, the configuration and assembly are simple, and the control is easy.

[0023]

Third Embodiment FIGS. 9 to 13 show a third embodiment of the present invention, wherein the same elements as those in the first embodiment are denoted by the same reference numerals and correspond to each other. In this embodiment, the switching structure of the mold opening and the self-holding of each of the plurality of cavity units is different. The fixed-side cavity unit 2 includes a fixed-side mold plate 5 that is in close contact with the movable-side cavity unit 1 described later, and a fixed-side mounting plate 9 that is detachably attached to a fixed-side platen 17 via the fixed-side holding plate 4. I have. The fixed side mold plate 5 and the fixed side mounting plate 9 have the same connection structure as in the first embodiment. As shown in FIG. 12, the fixed side mounting plate 9
Spacers 2 on a pair of upper and lower side walls (the lower side is not visible)
A lock ring 11 is provided as lock means rotatable with respect to the stop pin 20 through the lock pin 2. As shown in FIG. 9, the lock ring 11 has a recess 11 having a width H on the upper surface side.
b and the protrusions 11a are alternately formed into five equal parts,
A gear 11d having ten teeth is formed on the side surface, and a saw tooth 11e equally divided into ten is formed on the bottom surface.

The fixed holding plate 4 and the movable side cavity unit 1 are provided with hook members 3 and 12, respectively. The hook member 3 in the fixed-side cavity unit 2 has a hook piece 3a that is slightly smaller than the width H and extends in the mold opening direction, and the hook piece 3a engages with the convex portion 11a and the concave portion 11b of the lock ring 11. And withdrawal.

On the other hand, the hook members 12 in the movable side cavity unit 1 are fixed to the upper end surface and the lower end surface of the movable side cavity unit 1, respectively. At the tip of each hook member 12, the width H of the recess 11b of the lock ring 11 is provided.
A hook piece 12a having a somewhat smaller size is formed, and the hook piece 12a engages with and disengages from the convex portion 11a and the concave portion 11b of the lock ring 11. Each hook member 12 has a click 30 that contacts the valley portion 11f of the gear 11d formed on the lock ring 11 when the mold is clamped,
A spring 24 for generating a pressure in the pressing direction with respect to the valley portion 11f and the click 30 is incorporated (see FIG. 10). Further, the fixed side holding plate 4 and the movable side cavity unit 1 are provided with hook blocks 23 and 27, respectively.
Hook block 2 in movable side cavity unit 1
3 includes a hook rod 23b slidable in the mold clamping direction and a spring 23e for pressing the hook rod 23b toward the lock ring 11, as shown in FIG. Further, a hook claw 23a for transmitting a rotational force to the lock ring 11 by pressing against the saw tooth 11e formed on the lock ring 11 against the movement in the mold clamping direction is provided at the tip of the rod 23b. In this case, the hook claw 23a is rotatable with respect to the rotation shaft 23c, and the rotation is restricted by the spring 23d. The hook block 27 in the fixed side holding plate 4 has the same structure as the hook block 23.

Next, the operation of this embodiment will be described by taking a mold having two cavity units as an example. In advance, the first cavity unit is opened, that is, the hook member 12 of the movable side cavity unit 1 is disengaged from the lock ring 11 and the hook member 3 of the fixed side holding plate 4 is engaged with the lock ring 11. , The second cavity unit is positioned in a self-holding state. In the first cavity unit, when the movable platen 15 (not shown) is moved to perform mold clamping, the hook pieces 12 a of the hook member 12 start to be fitted into the concave portions 11 b of the lock ring 11. At the same time, the hook claw 23a of the hook block 23 presses the saw tooth 11e to rotate the lock ring 11, but
The lock ring 11 cannot rotate while the hook pieces 12a are fitted in the recesses 11b. Therefore, the hook rod 23b bends the spring 23e. When the mold is completely closed, the hook pieces 12a and the concave portions 11b are completely fitted, and the lock ring 11 becomes rotatable. The hook rod 23b rotates the lock ring 11 via the hook claw 23a and the saw tooth 11e by the compression force of the spring 23e. The lock ring 11 is rotated by one peak of the gear 11d and stopped by the click 30 pressing the valley 11f of the gear 11d. The hook member 12 of the movable side cavity unit 1 and the lock ring 11 are engaged, and at the same time, the engagement between the hook member 3 of the fixed side holding plate 4 and the lock ring 11 is released. On the other hand, in the second cavity unit, the engagement between the hook member 12 of the movable side cavity unit 1 and the lock ring 11 is released, and the hook member 3 of the fixed side holding plate 4 and the lock ring 11 are engaged.

In injection molding, the molten resin is injected into the first cavity unit by switching the valve device of the hot runner manifold 14 (not shown). When the movable platen is retracted after removing the holding pressure after injection, the first cavity unit self-holds the mold clamping force, and the second cavity unit opens the parting line surface and takes out the molded product. Can be. There is no molded article in the first time. Then, the mold is clamped again to perform the same operation, and the first cavity unit is released from the self-holding of the mold clamping force, and the second cavity unit is in the self-holding state with the mold clamping force.

In this embodiment, since the ON / OFF switching of the self-holding of the mold unit clamping force of the cavity unit is performed by the movement of the mold opening, an actuator is not required and automation can be facilitated.

[0029]

Fourth Embodiment FIG. 14 shows a fourth embodiment of the present invention, wherein the same elements as those in the first embodiment are denoted by the same reference numerals and correspond to each other. In this embodiment, the configurations of the hot runner manifold 14 and the valve device 14b are different. The hot runner manifold 14 forms a flow path 14 a for the molten resin, includes a valve device 14 b, and is built in the fixed-side holding plate 4.
The valve device 14b is slidable in the mold clamping direction, and is provided so as to be freely detachable from the resin hole 4a of the fixed holding plate 4. Reference numeral 30 denotes an actuator for sliding the valve device 14b, which is built in the fixed-side holding plate 4. In such a structure, the sliding movement of the actuator 30 causes the valve device 14b to engage with or disengage from the resin hole 4a, thereby making it possible to switch between the flow state and the cutoff state of the molten resin.

[0030]

As described above, according to the present invention, the switching of the supply of the molten tree by the switching means provided in the manifold flow path for each of the plurality of cavity units which are separated and exposed is performed by the mold clamping operation and the mold opening operation. Since they are linked, it is not necessary to move, attach / detach, or replace the cavity unit, and the molding cycle can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a perspective view of a lock member.

FIG. 3 is a cross-sectional view of a hot runner manifold.

FIG. 4 is a front view of FIG. 3;

FIG. 5 is a sectional view of a valve device.

FIG. 6 is a cross-sectional view of the valve device.

FIG. 7 is a perspective view of a second embodiment.

FIG. 8 is a plan view of FIG. 7;

FIG. 9 is a perspective view of a third embodiment.

FIG. 10 is a sectional view of a hook member.

FIG. 11 is a plan view of a hook block.

FIG. 12 is a sectional view of a lock ring.

FIG. 13 is a bottom view of the lock ring.

FIG. 14 is a sectional view of the fourth embodiment.

[Explanation of symbols]

 Reference Signs List 1 movable side cavity unit 2 fixed side cavity unit 14 hot runner manifold 14a flow path 14b valve device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuo Suga 2-43-2 Hatagaya, Shibuya-ku, Tokyo Within O-limpus Optical Industries Co., Ltd. (72) Inventor Kazuo Saito 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Shozo Nishida 1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima Japan Steel Works Co., Ltd. Hiroshima Works (56) References JP-A-5-50468 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (2)

(57) [Claims] 1. A movable-side cavity unit, a fixed-side cavity unit that forms a cavity when one surface comes into close contact with the movable-side cavity unit, and a contact surface when the movable-side and fixed-side cavity units come into close contact with each other. An elastic member that urges the fixed-side cavity unit to be in close contact with the movable-side cavity unit; a first holding member that can hold the fixed-side cavity unit away from the movable-side cavity unit in a mold opening direction; And a second holding member provided on the fixed side cavity unit and capable of holding the fixed side cavity unit on the movable side cavity unit side and an engagement position with the first holding member or a second holding member. The fixed side cavity is selectively operated at an engagement position with the first and second holding members when the fixed side cavity is engaged with the first or second holding member. And a lock means that can hold the memory unit, and a plurality of such sets are arranged side by side apart from each other, and a resin is provided in each of the cavities formed by the movable side and the fixed side cavity units. A manifold for forming a resin flow path for distributing the molten resin injected from the molding nozzle; and switching means provided in the flow path of the manifold for switching between supply and cutoff of the molten resin to the cavity. Injection molding dies. 2. An injection molding method for injecting a molten resin from a resin injection nozzle into a cavity after a movable platen is moved forward to a fixed platen side in an injection molding machine to clamp a mold. At least two sets of a pair of cavity units are arranged between the fixed-side platen and the movable-side platen, and at least one set A is self-held and at least one set B is opened. The other one of the sets AB, in which each one of the cavity knits is arranged side by side on the movable side mounting plate on the movable side platen side so as to be separated from each other, and is arranged side by side on the fixed side platen side facing the movable side mounting plate so as to be separated from each other The other cavity unit of the set B in the mold-opened state is held against the holding member on the fixed platen side capable of holding the respective cavity units. Next, the movable-side platen is moved forward to clamp the cavity unit A in the self-holding state and the cavity unit B in the mold-opened state on the movable-side mounting plate. The molten resin is supplied from the nozzle via the resin flow path of the manifold to the cavity of the cavity unit B in a state where the mold is opened, and a predetermined amount is supplied to the cavity. The supply of the molten resin to the cavity is interrupted by the switching means provided in the above, and the engagement position for holding the holding member provided in the other cavity unit of the cavity unit B and the disengagement for releasing the holding. The operation of the locking means operable to the first position and the second position allows the one cavity unit and the other The set B of the unit is held in a self-holding state, and the supply of the molten resin to the cavity by the switching means provided in the resin flow path of the manifold is performed for the cavity unit A in the state of being held in the self-holding state. The lock unit continues to be shut off, and the lock unit is moved to the disengagement position where the lock unit is operable between the engagement position for holding the holding member provided on the other cavity unit of the cavity unit A and the disengagement position for releasing the holding. By releasing the self-holding cavity unit A, the self-holding state is released, and the other cavity unit is held by the holding member on the fixed-side platen side. Then, the movable-side platen is retracted. The pair B is retracted together with the movable platen as a self-holding state,
An injection molding method, wherein a molded product is taken out with the other set A of cavity units opened.