JP3432011B2 - Injection mechanism of injection molding machine - 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 mechanism used in an injection molding machine as a pair with a mold clamping mechanism.

[0002]

2. Description of the Related Art Conventionally, various injection molding machines have been known, but those in which a mold clamping mechanism and an injection mechanism reciprocate forward and backward are used. Generally, since the mold clamping mechanism and the injection mechanism require high-speed response,
As the drive source, an actuator using hydraulic pressure or pneumatic pressure, which features high-speed reciprocating motion, is used. Also,
In recent years, an increasing number of servo motors use a reciprocating rotary motion as a drive source.

On the other hand, an ordinary electric motor is unsuitable for controlling momentary start, momentary stop, and momentary forward / reverse rotation, so that it is difficult to put it into practical use in such a mold clamping mechanism and an injection mechanism. It was

[0004]

The injection mechanism of the conventional injection molding machine described above has the following problems.
In the case of hydraulic drive or pneumatic drive, a hydraulic pump, a pneumatic pump, etc. are required in addition to the actuator, which is not suitable for miniaturization. On the other hand, when a servo motor is used, a high output and low inertial one is required to improve the responsiveness, and a pulse coder for position detection and a numerical controller are required, resulting in high cost and high power consumption. It becomes electric power.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection mechanism of an injection molding machine which has a simple structure and excellent responsiveness, is easy to operate, and is inexpensive and compact. To do.

[0006]

In order to achieve the above object, the invention according to claim 1 provides a support base for supporting linear drive, and a drive fixed to the support base for rotationally driving a rotary cam in one direction. A motor, a cylindrical portion having a nozzle for injecting a thermoplastic resin molding material at one end and slidably supported so as to approach and separate from a pair of mold clamping mechanisms on the support table, and the rotation described above. A plunger part having a cam follower slidably contacting a cam and having a plunger slidably supported on the support base between the cylindrical part and the rotary cam and moving back and forth in the cylindrical part; A first urging mechanism that urges the plunger part away from the plunger part and a first urging mechanism that urges the plunger part toward the rotary cam via the cam follower while urging the plunger part away from the mold clamping mechanism. A configuration equipped with a second biasing mechanism for biasing.

The invention according to claim 2 is based on claim 1.
In the injection mechanism of the injection molding machine described above, the cylindrical portion is interposed between the mold of the mold clamping mechanism and the injection nozzle to form a flow path of the thermoplastic resin molding material and a runner. The third spout which supports the holding sprue part so as to be close to and away from the nozzle and normally biases the sprue part away from the nozzle with a spring constant smaller than that of the first biasing mechanism. It is configured to have a bias mechanism. Further, the invention according to claim 3 is an injection mechanism that is driven toward and away from the mold clamping mechanism to inject resin, and uses a rotating cam and a cam follower, and attaches the injection mechanism in one direction. The ejection mechanism is reciprocally driven by the reciprocating motion of the cam follower while being urged.

[0008]

In the invention according to claim 1 configured as described above, when the drive motor fixed to the support base rotationally drives the rotary cam in one direction, the plunger portion provided with the cam follower slidably contacting the rotary cam is provided. Since the second biasing mechanism biases the rotary cam via the cam follower so as to press the rotary cam, a reciprocating linear motion is started via the cam follower according to the shape of the rotary cam. Here, since the second urging mechanism urges the plunger part in the direction of separating from the mold clamping mechanism, when the plunger part is driven so as to approach the mold clamping mechanism, the pressing operation is accumulated.
When it is driven in the opposite direction later, the force is increased to assist the movement.

The plunger portion is interposed between a cylindrical portion slidably supported on the support base and the rotary cam, and the first biasing mechanism biases the cylindrical portion in a direction away from the plunger portion. Therefore, as the plunger portion is driven, the cylindrical portion also comes close to the mold clamping mechanism. A thermoplastic resin molding material injection nozzle is provided at the other end of the cylindrical portion, and when it is in close proximity to the mold clamping mechanism and comes into contact with the mold, an injection path for the thermoplastic resin molding material is formed. . Further, even if the rotary cam rotates to drive the plunger portion toward the mold clamping mechanism, the cylindrical portion cannot move any further.
However, since the cylindrical portion and the plunger portion are slidably supported, the intervening first urging mechanism starts contraction and the plunger portion and the cylindrical portion start to approach each other. At this time, since the plunger of the plunger portion enters into the cylindrical portion, the molten resin material inside is pushed out from the injection nozzle into the mold of the mold clamping mechanism.

On the other hand, after injecting the resin, the rotary cam further rotates and the plunger portion begins to separate from the mold clamping mechanism.
At this time, the second urging mechanism assists such movement, exhibits high-speed responsiveness, and returns to the initial position. That is, the second urging mechanism, the rotating cam, and the cam follower cooperate to accumulate the reciprocating motion pressing force in one direction and increase the movement in the opposite direction. Instead, it exhibits high-speed responsiveness such as momentary start, momentary stop, and momentary forward / reverse motion. Further, in the invention according to claim 2 configured as described above, the third biasing mechanism biases the sprue portion away from the injection nozzle, and the cylindrical portion contacts the mold clamping mechanism. The sprue part and the injection nozzle are separated. Then, when the cylindrical portion further advances, the third urging mechanism contracts and the sprue portion and the injection nozzle come into close contact with each other. As a result, an injection path from the injection nozzle to the mold of the mold clamping mechanism is formed, so that the molten resin material is injected as described above. When the plunger part starts to return, the sprue part and the injection nozzle finally separate and cut off the injection path. The retained runners are removed.

Further, while urging the injection mechanism which is driven toward and away from the mold clamping mechanism to inject the resin in one direction, the rotary cam and the cam follower are used to reciprocate the injection mechanism together with the cam follower. It may be operated and driven. Here, since it is biased in one direction, the force is accumulated when moving in the reverse direction, and the driving force is assisted when moving in the forward direction to exhibit high-speed response.

[0012]

As described above, according to the present invention, by using the unidirectional rotating cam and the cam follower and urging the unidirectional movement, it is possible to simplify the operation without using the servomotor. It is possible to provide an injection mechanism of an injection molding machine capable of exhibiting high-speed responsiveness with the configuration.

According to the second aspect of the present invention, the spring constant is reduced and the sprue portion is held in front of the injection nozzle, so that the injection mechanism can be carried out without a specific drive mechanism. It is sometimes closely attached to the injection nozzle and is held away from the injection nozzle during standby.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view showing an injection molding machine to which an injection mechanism according to an embodiment of the present invention is applied, and FIG. 2 is a front view thereof. In addition, FIG. 3 shows III in FIG.
3 is a sectional view taken along line III-III and FIG. 4 is a sectional view taken along line IV-IV in FIG. The injection molding machine according to the present embodiment includes a support base unit 100 that supports each unit, and an injection mechanism unit 200 that is slidably supported on the support base unit 100.
Similarly, the mold clamping mechanism unit 300 is supported on the support base unit 100 so as to be slidable coaxially with the injection mechanism unit 200.

The support base unit 100 includes a horizontal base 11
1 and three vertical bases 112a to 112 fixedly installed on the upper surface of the base 111 at a predetermined interval.
c and two columnar support rails 113 and 113 that are horizontally arranged so as to skewer these vertical bases 112a to 112c.
3, the injection mechanism unit 200 and the mold clamping mechanism unit 300 are slidably supported. Although the support rail 113 is used in the present embodiment, it may be configured so as to be slidably supported by using a groove, a rail having another shape, a tubular body, or the like.

An electric motor equipped with a one-way rotary reduction gear is vertically installed below the support base unit 100.
The output shaft 121 penetrates the base 111 between the vertical bases 112a and 112b. Further, two rotary cams 122 and 123 are fixed to the output shaft 121, the upper rotary cam 122 is supported at substantially the same height as the support rails 113 and 113, and the lower rotary cam 123 is generally supported. It is supported at the same height as the base 111. In addition,
As the electric motor, for example, a general-purpose machine for a belt conveyor can be diverted and used. Injection mechanism unit 2
Reference numeral 00 denotes a cam follower slide base 211 slidably supported by being penetrated by the support rails 113, 113 between the vertical bases 112a, 112b, and similarly slid by being penetrated by the support rails 113, 113 between the vertical bases 112b, 112c. Plunger part slide base 212 supported so as to be possible, and by connecting them, it is possible to move horizontally linearly along the support rails 113, 113.

The cam follower slide base 211 includes slide arm portions 211a and 211a which are penetrated by the support rails 113 and 113, and a plunger portion slide base 2.
It comprises a connecting arm portion 211b screwed to 12 and a base portion 211c intermediate between these, and a roller pin 211d is projected and supported on the lower surface of the base portion 211c. The roller pin 211d corresponds to the rotary cam 122 of the output shaft 121, and is located on the vertical base 112b side with respect to the side surface of the rotary cam 122. On the other hand, on the outer periphery of the support rails 113, 113, the arm parts 211a, 211a of the cam follower slide base 211 and the vertical base 1 are provided.
Coil spring 21 so as to be interposed between the coil spring 21 and
3, 213 are mounted and the injection mechanism unit 2
00 is urged toward the vertical base 112a, and the roller pin 211d is pressed against the cam surface of the rotating cam 122 and stopped. In this embodiment, the coil spring 21
Although the cam follower slide base 211 is urged in the direction of pulling the cam follower slide base 211 away from the vertical base 112b in FIG. 3, a spring having another shape or another elastic body may be urged.

The plunger slide base 212 includes:
A through-hole 212a is formed in the central portion, and a cap-shaped back pressure support housing that covers the opening of the through-hole 212a on the side of the vertical base 112a and that is screwed to the connecting arm portion 211b of the cam follower slide base 211. 214 is fixed by bolts. Through hole 2
The stepped portion 212a1 is formed so that the opening portion on the side of the vertical base 112c in 12a has a small diameter, and the plunger support plate 215 having the stepped portion corresponding to the stepped portion 212a1 formed on the outer peripheral surface is inserted into the through hole 212a. Then, a back pressure coil spring 216 for urging the plunger support plate 215 in the pushing direction is inserted inside the back pressure support housing 214. As a result, the plunger support plate 215 is attached to the plunger slide base 2
The 12 through holes 212a are closed with a predetermined pressure. The plunger 21 is provided on the outer surface side of the plunger support plate 215.
Since 7 is supported so as to project horizontally, adjustment is made so that the pressure does not exceed the pressure of the back pressure coil spring 216 when the plunger 217 pushes the molten resin, as will be described later.

Four through holes 221 are formed around the through hole 212a in the plunger portion slide base 212 so as to surround the through hole 212a, and the vertical base 112 is formed.
Four slide bolts 222 penetrate from the side of a. The slide bolt 222 is formed with a male screw only at its tip portion, and is screwed into a female screw portion 223a of a cylindrical portion (hereinafter referred to as a cylinder mounting base) 223 at a position separated from the plunger slide base 212 by a predetermined distance. There is. A coil spring 224 is mounted around the slide bolt 222 so as to urge the plunger slide base 212 and the cylinder mounting base 223 to separate from each other, and the coil spring 224 in the plunger slide base 212 and the cylinder mounting base 223 is urged. A large-diameter concave portion is formed at the contact portion to accommodate the end portion of each coil spring 224. In this embodiment, the coil spring 224
Although the cylinder mount 223 is biased in the direction of pulling it away from the plunger slide base 212, it may be a spring having another shape or may be biased by another elastic body.

A through hole 223b is formed in the center of the cylinder mount 223 with the same axis as the plunger 217, and one end of the heating cylinder 230 is screwed from the side opposite to the plunger slide base 212. The plunger 217 penetrates the through hole 223b and is inserted into the heating cylinder 230. As described above, the cylinder mount 223 and the plunger portion slide base 212 are connected to each other by the coil spring 224.
Although it is urged in a direction to pull it away, it can also be slid to approach, and at this time, the plunger 21 protruding from the side of the plunger slide base 212 is protruded.
7 enters the inside of the heating cylinder 230 and pushes out the molten resin. An injection nozzle 231 is formed at the tip of the heating cylinder 230, a heater 232 is attached to the outer periphery on the tip side, and a torpedo 233 is housed inside a portion corresponding to the heater 232. Further, a hopper 234 is arranged above the heating cylinder 230.

The sprue portion 24 is provided on the tip side of the heating cylinder 230.
0 is held. The sprue portion 240 is screwed to the tips of the four slide bolts 241 penetrating the cylinder mounting base 223 in the same manner as the cylinder mounting base 223 is held to the plunger slide base 212 via the slide bolts 222. And is fixed by the coil spring 242 around the slide bolt 241.
Is interposed to urge the sprue portion 240 in a direction in which the sprue portion 240 is separated from the cylinder mount 223. FIG. 5 shows the sprue portion 240 from the side direction, FIG. 6 shows the sprue portion 240 from a sectional view seen from the front direction, and FIG. 7 shows the sectional view seen from above. The sprue part 240 includes a sprue base 243 that covers the front surface of the heating cylinder 230. The sprue base 243 is formed with a circulation hole 243a facing the injection nozzle 231, and slide plates 244 and 244 that slide in the left-right direction are formed on the front side of the circulation hole 243a by springs 243b.
Are held in a state of being urged toward each other at. Semicircular grooves 244a, 244a are formed on the abutting surfaces of the slide plates 244, 244 so as to face the flow hole 243a, and the groove 244a becomes wider toward the flow hole 243a side. It should be noted that each slide plate 244 has a guide hole 244b having a tapered surface on the periphery thereof.
Is formed, and when the eccentric cone-shaped guide described later is inserted, the tapered surfaces are brought into sliding contact with each other and act so as to move to the center so as to match the axial centers, so that it acts against the spring 243b. Move to the center.

A runner cutter 245 for sandwiching the sprue base 243 is disposed above the flow hole 243a. The runner cutter 245 is biased upward by a spring 246, and one end of the pallet fork 247 is connected to the upper end thereof via a support pin 247a. The pallet fork 247 is formed in a crank shape, and is rotatably supported by a support arm 248 that is supported by protruding from the upper end of the sprue base 243 toward the heating cylinder 230 side. The other end of the pallet fork 247 faces the pallet fork 249 fixed to the base 111 so as to straddle the upper side of the heating cylinder 230, and when the plunger portion slide base 212 reciprocates as described later. It comes into contact with or separates from the pallet fork bar 249. At this time, the pallet fork 249 rotates around the support point of the support arm 248 as a fulcrum, and vertically moves the runner cutter 245 via the support pin 247a at one end.

The mold clamping mechanism unit 300 has a mold slide plate 311 arranged on the upper surface of the base 111, and two roller pins 312 projectingly arranged on the lower surface of the mold slide plate 311. , 313 sandwiches the lower rotary cam 123 fixed to the output shaft 121 penetrating the mold slide plate 311. Rotating cam 123
Is formed with two cam surfaces 123a and 123b so as to come into contact with the respective roller pins 312 and 313,
Further, the base 111 is formed with a through hole through which the output shaft 121 and the roller pins 312 and 313 can pass. The mold slide plate 311 has cam surfaces 123a, 1
It reciprocates on the base 111 according to the sliding contact condition between the roller 23b and the roller pins 312 and 313.

As shown in FIG. 8, the mold slide plate 311 extends below the heating cylinder 230 toward the side of the vertical base 112c, near the tip of the heating cylinder 230, and above the ankle bar 249. It is fixed to a mold slide base 314 slidably supported on the support rails 113, 113 on the vertical base 112b side. The mold slide base 314 includes parallel slide pins 315 and 315 arranged horizontally outside the support rails 113 and 113. The slide pins 315 and 315 penetrate the vertical base 112c. It is fixed to the mold end bar 316 on the opposite side.

At the center of the mold end bar 316 in the width direction, the vertical base 11 projects toward the vertical base 112c.
The end of the movable mold part 320 that penetrates 2c is fixed. On the other hand, on the side of the vertical base 112c, a cylindrical fixed mold part 330 that accommodates the movable mold part 320 is arranged. The movable mold part 320 reciprocates in the fixed mold part 330 when the mold end bar 316 reciprocates by the slide pins 315, 315, and when the movable mold part 320 moves to the most vertical base 112b side. The movable mold 321 provided at the tip of the
A fixed mold 331 provided at the tip of 0 forms an integrated mold for resin molding.

The sprue portion 240 of the fixed mold 331
A runner surface 332 communicating with the flow hole 243a of the sprue portion 240 is formed on the surface on the side of, and the guide holes 24 of the slide plates 244, 244 are formed on both sides thereof.
Cone-shaped guide 333 facing 4b and 244b
333 is formed to project. On the other hand, the movable mold part 3
A protrusion pin 322 penetrating the movable mold 321 is provided inside the unit 20, and the protrusion pin 322 is fixed to the support plate 322a on the back side of the movable mold 321. The support plate 322a is biased by a spring 322b in the direction of being pulled out from the movable mold 321, and the support plate 322a is moved in the width direction of the movable mold part 32.
Wing 3 which penetrates 0 and the fixed mold part 330 to project
It is in contact with 23. A slit that can be moved back and forth while being penetrated by the wing 323 is formed on the side surface of the movable mold part 320, and the wing 323 is the fixed mold part 3.
It is fixed to the vertical base 112c together with 30. An opening 334 for dropping the resin molded product is formed in the lower part near the tip of the fixed mold part 330, and a chute 335 is arranged in the lower part. Similarly, a chute 250 for discharging the runner is also provided below the sprue portion 240.

Next, the operation of this embodiment having the above configuration will be described. In the injection molding machine of this embodiment, the rotating cams 122 and 123 also rotate once while the output shaft 121 rotates once, and the roller pin 211d and the roller pins 312 and 313 contacting these rotating cams 122 reciprocate to perform injection. The mechanical unit 200 and the mold clamping mechanism unit 300 are reciprocated. The rotary cam 122 accompanying the rotation of the output shaft 121,
A timing chart of 123 and the roller pins 211d, 312, and 313 is shown in FIG. Injection mechanism unit 2
The initial state of 00 is, as shown in FIG.
The roller pin 211d is inserted in the recessed portion.
In the timing chart, the injection mechanism unit 200 is closest to the rotating cam 122 when the phase is 0 degree. Therefore, the operation in which the rotary cam 122 rotates and the roller pin 211d separates from the rotary cam 122 is called forward movement, and the reverse operation is called backward movement. In addition, the mold clamping mechanism unit 3
At 00, conversely, the operation of approaching the injection mechanism unit 200 is called forward movement, and the operation in the opposite direction is called backward movement.

When the rotary cam 122 starts to rotate in the clockwise direction, the roller pin 211d is pushed out by sliding contact with the slope of the rotary cam 122 that extends from the concave portion to the convex portion, and the roller follower slide base 211 to which the roller pin 211d is fixed. Begins to move forward. At this time, the arm portion 211a of the cam follower slide base 211 is attached to the support rail 1
The coil spring 213 is compressed in order to move along 13 toward the vertical base 112b. The cam follower slide base 211 is fixed to the plunger portion slide base 212 at one end, and the plunger portion slide base 212 also starts moving forward.

When the plunger slide base 212 starts to move forward and reaches timing A (phase 22.4 degrees),
Sprue part 24 supported by cylinder mount 223
0 contacts the tip of the fixed mold part 330 of the mold clamping mechanism unit 300. Then, when the plunger portion slide base 212 further attempts to move forward, the coil spring 242 having a small spring constant begins to contract, and the cylinder mount 22
3 moves forward while the coil spring 224 maintains the state of being separated from the plunger slide base 212. The movement of the sprue part 240 during this time is performed as follows. As the cam follower slide base 211 moves forward, the sprue portion 240 itself also starts moving forward at the same time, so the pallet fork 247 protruding rearward from the upper portion is fixed to the base 111.
Start leaving 49. Then, the pallet fork 247 is rotated by the urging force of the spring 246, and the runner cutter 24
5 is pushed up. When the runner cutter 245 is pushed up, the slide plates 244, 24 facing each other
There will be no obstacles in between 4.

The sprue part 240 moves forward and the fixed mold part 3
When approaching 30, the cone-shaped guides 333, 3
33 is a guide hole 244b of the slide plates 244, 244,
It enters into 244b. Guide holes 244b, 244
Since the distance between the centers of b is wider than the distance between the centers of the guides 333 and 333, the sprue portion 240 is fixed to the fixed mold portion 33.
As it approaches 0, the guide 333 guides the guide hole 244b.
The slide plates 244, 244 are connected close to each other by the action of the respective tapered surfaces. After that, the coil spring 242 contracts until the timing B (phase 28 degrees) is reached, and the tip of the heating cylinder 230 comes into contact with the back surface of the sprue base 243. Then, the injection nozzle 231
2 between the through hole 243a and the two slide plates 244
A flow path of the molten resin is formed to reach the runner surface 332 of the fixed mold 331 via 44a.

After the timing B, the heating cylinder 230 cannot move forward and is stopped.
Since the plunger slide base 212 is close to the coil spring 224, the coil spring 224 contracts and the plunger 217 begins to enter the heating cylinder 230. Then, the molten resin inside starts to be injected through the injection nozzle 231. On the other hand, like the forward movement of the injection mechanism unit 200, the mold clamping mechanism unit 300 has also started its operation, and the cam surface 123a of the rotary cam 123 presses the roller pin 312, so that the roller pin 312 is supported. The mold slide plate 311 that is open is drawn. Since the end of the mold slide plate 311 is fixed to the mold slide base 314, the mold slide base 314 moves forward along the support rail 113 and pulls the mold end bar 316 through the slide pin 315. To move forward. When the mold end bar 316 advances, the movable mold part 320 also advances, and when the timing C (phase 40 degrees) is reached, the movable mold 321 at the tip contacts the back surface of the fixed mold 331 and the mold clamping is completed. Of course, at this time, the ejection pin 322 is in a state of being pulled out from the movable mold 321. Although the mold clamping is completed after the injection of the molten resin is started as described above, there is no problem because the molten resin is extruded while filling the flow hole 243a, the runner surface 332, and the like.

The pushing of the molten resin by the plunger 217 is performed before and after the completion of the mold clamping.
The molten resin is filled in the mold while being subjected to a predetermined pressure by the force by which 17 moves forward. This pressure is preferably adjusted so as to be a predetermined pressure, and conventionally, a complicated control must be performed by using a sensor for this pressure adjustment. However, in this embodiment, when the plunger 217 tries to push the molten resin at a pressure higher than the predetermined value when the plunger slide base 212 moves forward, the back pressure coil spring 216 contracts so that the pressure does not exceed the predetermined pressure. To Then, when the pressure decreases, it expands to increase the pressure so that it becomes a constant pressure. That is, the back pressure coil spring 216 supporting the plunger support plate 215 adjusts the filling pressure of the molten resin. And timing D (phase 70 degree)
Even if the plunger slide base 212 stops, the molten resin is continuously pushed in and the pressure is maintained until the contracted back pressure coil spring 216 returns to the original length.

When the back pressure coil spring 216 returns to its original length, the molten resin inside the mold begins to cool and begins to solidify, and then slightly contracts, so that the pressure inside the mold gradually decreases. Then, at timing E (phase 280 degrees), as shown in FIG. 9, the roller pin 312 moves to the cam surface 1.
The pressure is released all at once because it faces the concave portion of 23a. At timing G (phase 315 degrees), the roller pin 211d starts to face the concave portion of the rotating cam 122, and therefore the cam follower slide base 211 and the plunger portion slide base 212 start to retreat due to the restoring force of the coil spring 213. This retraction improves the extremely high speed response because the coil spring 213 drives the cam follower slide base 211 by the force that has been compressed by then. Further, timing F (phase 317.
At 5 degrees), the cam surface 123b of the rotating cam 123 starts to contact the roller pin 313, pushes out the roller pin 313, and starts moving the movable mold part 320 backward. As the movable mold part 320 moves backward, the resin molded product moves to the movable mold 3.
Pin 3 protruding so that it does not remain stuck to 21
22 penetrates the movable mold 321 and comes out into the mold.

On the other hand, in the injection mechanism unit 200, even if the plunger slide base 212 starts to retreat, initially the coil spring 224 only begins to expand and the heating cylinder 230 and the sprue 240 remain connected. , The sprue part 240 is still in contact with the fixed mold 331. Then, at timing I (phase 332 degrees), the coil spring 224 moves to the slide bolt 222.
When extended to the length regulated by, the coil spring 242 begins to extend to the allowable range of the slide bolt 241, and the heating cylinder 230 separates from the sprue portion 240. Finally, at timing J (phase 337 degrees), the sprue portion 240 begins to separate from the fixed mold 331. At this time, the runner solidified by the runner surface 332 of the fixed mold 331 is formed on the slide plate 244. It is torn off while being held on the side of the sprue portion 240 by the groove 244a which spreads toward the end. Further, as the sprue portion 240 moves away from the fixed die 331, the guide 333 comes out of the guide hole 244b, so that the slide plates 244, 24 slide along the tapered surface.
4 begins to open. The resin molded product stuck to the mold surface of the fixed mold 331 as the runner is torn off drops to the chute 335 through the opening 334.

As the sprue part 240 further retracts, the pallet fork 247 contacts the pallet fork 249, so that the pallet fork 247 rotates to lower the runner cutter 245. Then, the runner in which the lower surface of the runner cutter 245 is attached to the flow hole 243a is cut and dropped to the lower chute 250. As described above, the output shaft 121 makes one rotation, and one resin molded product is completed. As described above, in the present embodiment, the structure of the injection molding machine in which the motion of the drive source is unidirectionally rotated and the motion is reciprocated through the rotary cam and the spring in each of the mold clamping mechanism and the injection mechanism, did. That is, as its structure,
In a single-cylinder heating type plunger injection molding machine, the injection mechanism unit and the mold clamping mechanism unit are symmetrically arranged via a fixed mold attached and fixed to the main body of the injection molding machine,
The injection mechanism unit moves so as to be capable of pressure contact (advance) and separation (retraction) facing the runner surface of the fixed mold section, and the mold clamping mechanism unit faces pressure contact (opposite direction) of the gate surface of the fixed mold section. It moves forward and away (backward). As a result, the conventional unidirectional rotary reduction gear mechanism-equipped electric motor, which has been difficult to put into practical use, is used as a drive source for the injection molding machine.
It is possible to provide an inexpensive and small-sized electric injection molding machine which has a simple structure and is excellent in responsiveness, does not require injection condition setting at the time of driving operation, and is easy to operate.

[Brief description of drawings]

FIG. 1 is a plan view of an injection molding machine to which an injection mechanism according to an embodiment of the present invention is applied.

FIG. 2 is a front view of the injection molding machine.

3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a side view of the sprue portion.

FIG. 6 is a cross-sectional view near the sprue portion.

FIG. 7 is a cross-sectional view near the sprue portion.

FIG. 8 is a plan view showing a mold slide plate.

FIG. 9 is a timing chart of a rotating cam.

[Explanation of symbols]

100 ... Support unit 111 ... Base 113 ... Support rail 121 ... Output shaft 122, 123 ... Rotating cam 123a, 123b ... Cam surface 200 ... Injection mechanism unit 211 ... Cam follower slide base 211d ... Roller pin 212 ... Plunger base slide base 217 ... Plunger 222 ... Slide bolt 223 ... Cylinder mount 224 ... Coil spring 230 ... Heating cylinder 231 ... Nozzle for injection 240 ... Sprue part 241 ... Slide bolt 242 ... Coil spring 300 ... Mold clamping mechanism unit

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Claims (2)

(57) [Claims] 1. A support base that supports linear drive, a drive motor that is fixed to the support base and drives a rotary cam to rotate in one direction, and a thermoplastic resin molding material injection nozzle at one end. A cylindrical portion slidably supported so as to come close to and away from a pair of mold clamping mechanisms on a support base, and a cam follower slidably contacting the rotary cam, and the cylinder portion and the rotation on the support base. A plunger portion having a plunger slidably supported between the cam and moving back and forth in the cylindrical portion; and a first biasing mechanism for biasing the cylindrical portion in a direction away from the plunger portion,
And a second urging mechanism that urges the plunger portion so as to press the rotary cam through the cam follower while urging the plunger portion away from the mold clamping mechanism. mechanism. 2. The injection mechanism of the injection molding machine according to claim 1, wherein the cylindrical portion is interposed between the mold of the mold clamping mechanism and the injection nozzle, and the thermoplastic resin molding material. The sprue portion that forms the flow path of the runner and that holds the runner is supported so as to be close to and away from the nozzle, and normally, the sprue portion is separated from the nozzle with a spring constant smaller than that of the first biasing mechanism. An injection mechanism of an injection molding machine having a third urging mechanism for urging the injection molding machine.