JPH0321944Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a thread molding mechanism, and more specifically, in an injection molding device or the like, the present invention relates to a thread molding mechanism that is used in a molded product cavity defined by a mold equipped with a thread molding core pin. When manufacturing a molded product by supplying molten metal and solidifying the molten metal, the core pin is removed from the molded product while being screwed, and then the core pin is returned to its original position without being screwed. The present invention relates to a thread forming mechanism for a molding apparatus, etc., which can significantly improve molding efficiency and produce molded products at low cost.

BACKGROUND ART In various molding methods using molds, such as injection molding, it is widely practiced to integrally form a threaded portion as a female thread or a male thread on a molded product. Forming the threaded part in the molding process in this way eliminates the need to newly carve the threaded part in the post-processing process, which is extremely advantageous because it shortens the manufacturing time of the molded product and also reduces manufacturing costs. Become.

Therefore, next, a general molding method for integrally forming a female screw on a molded product will be described.

In FIG. 1a and FIG. 1b, reference numeral 2
and 4 indicate molds, and a cavity 6 is defined by clamping these molds 2 and 4.
A hole 8 communicating with the cavity 6 is formed in the mold 2, and a core pin 10 for forming a female screw is inserted into the hole 8. In this case, the core pin 10 includes a columnar body 12 and a screw type 14 made of a male screw provided at the tip of the columnar body 12. In FIG. 1a, the cylindrical body 12 is inserted into the hole 8, and the screw mold 14 projects into the cavity 6. Further, a rotation drive mechanism (not shown) is connected to the core pin 10, and the core pin 10 is configured to be able to reciprocate in the axial direction while rotating, that is, to be able to perform a spiral movement.

When manufacturing a molded product, first, molten resin is filled at a predetermined pressure into a cavity 6 defined by clamping the mold through a flow path (not shown). This molten resin cools and solidifies over time, forming the molded product 1.
It becomes 6. Next, by driving a rotation drive mechanism (not shown), the core pin 10 located at the position shown in FIG. 1A is rotated in the counterclockwise direction shown by arrow A and displaced in the direction of arrow B. That is, the core pin 10 is twisted and removed from the molded product 16 (see FIG. 1b). As a result, a female screw 18 corresponding to the screw mold 14 is formed. After that, the mold is opened by separating the mold 2 and the mold 4,
When the molded product 16 is taken out, the molding process is completed.

Incidentally, the injection pressure for filling the cavity 6 with molten resin is extremely high, and the core pin 10 is pressed in the direction of arrow B. Further, substantially, a male threaded portion (not shown) is formed in the cylindrical body 12 of the core pin 10, and under the screwing action of this male threaded portion and a female threaded portion (not shown), the injection pressure of the molten resin is received and , enables the core pin 10 to perform a spiral movement as described above. Therefore, in order to wait for the next molding process after opening the mold and taking out the molded product 16 from the state shown in FIG. need to be sent to. That is, by threading the core pin 0 in the opposite direction to when the core pin 10 is removed from the molded product 16, it is returned to the original position shown in FIG. 1a. In this way, when the core pin 10 is reciprocated in the directions of arrows B and D, the core pin 10 inevitably moves
There is no choice but to adopt a structure in which the motor rotates in the directions of arrows A and C.

However, when returning the core pin 10 from the position shown in FIG. 1b to its original position, the rotational movement of the core pin 10 in the direction of the arrow C itself is not necessarily necessary. This is because in this case, the screw mold 14 does not engage with other objects such as molded products at all. However, since the return stroke of the core pin 10 involves a rotational movement in the direction of arrow C, it is difficult to achieve a high speed return stroke. As a result, it is impossible to instantly return the core pin 10 to a predetermined position, and a significant improvement in production efficiency cannot be expected.

The present invention has been made to overcome the above-mentioned disadvantages, and includes a connecting rod connected to a core pin for forming a threaded portion, in which a stopper pin is housed so as to be able to protrude and displace, and a cam-shaped hole into which the stopper pin enters. The core pin is locked under the engagement action between the cam-shaped hole and the stopper pin, and further, while the connecting rod rotates, the stopper pin slides into the connecting rod under the sliding action of the cam-shaped hole. The locking state of the core pin is released when the locking state is released, and the positioning of the core pin can be performed reliably and quickly without rotating the core pin after the locking state is released. It is an object of the present invention to provide a thread forming mechanism such as a forming device that can be sent out to an initial position and positioned again.

In order to achieve the above object, the present invention comprises: a core pin having a threaded tip facing the cavity; a connecting rod connected to the core pin; and a connecting rod oriented in a direction crossing the axis of the connecting rod. a stopper pin that is slidably fitted into a pin storage hole formed in the connecting rod; a cam-shaped hole into which the stopper pin enters; and a stopper pin that is connected to the connecting rod via a rotational force transmitting means. a rotational drive source; and a pressing means for pressing a connecting rod integral with the core pin toward the core pin; the core pin is locked when the stopper pin enters the cam-shaped hole; The locking state of the core pin is released by rotating the connecting rod under the driving action of the power source and storing the stopper pin in the pin storage hole under sliding contact with the cam-shaped hole. It is characterized in that the core pin is removed from the molded product while being twisted, and after the molded product is removed from the mold, the core pin is returned to its original position under the pressing action of the pressing means.

Next, preferred embodiments of the thread forming mechanism according to the present invention will be described in detail with reference to the accompanying drawings.

In FIGS. 2a to 2c, reference numeral 20
1 shows a thread forming mechanism according to the present invention, and this thread forming mechanism 20 is incorporated into a mold 22 in a molding device. The mold 22 includes a first mold 24 and a second mold 26. A recess 28 is formed in the first mold 24, and a plate 30 is fixed to the recess 28 as a nest. No. 3 mold 32 is installed. In this case, the third mold 32 has a core pin 34 for forming the hole.
is implanted, and the tip of the core pin 34 projects into a molded product cavity 36 defined by the first and second molds 24, 26 and the third mold 32.

The thread forming mechanism 20 includes a core pin 38 for thread forming that is inserted into the plate body 30 and the third mold 32.
and the stopper pin 4 is inserted into the first mold 24 and
The connecting rod 42 includes a connecting rod 42 into which the connecting rod 0 is inserted, and a rotational force transmitting means 44 for transmitting rotational force to the connecting rod 42.

A screw type 46 made of a male screw is integrally formed at the tip of the core pin 38, and a locking portion 50 having a locking hole 48 is integrally formed at the other end of the core pin 38. The locking hole 48 is connected to the core pin 38
It extends in the axial direction and opens at the end face of the locking part 50. As shown in FIG. 3, the locking hole 48 consists of a hole with a square cross section. In this case, a hole 52 communicating with the cavity 36 is bored in the third mold 32, and the plate 30 is connected to the hole 52.
A hole 54 is formed in the third mold 32. Furthermore, the first mold 2 is connected to the hole 54.
A cam-shaped hole 56 and holes 58 and 60 are continuously formed in the hole 4 . A coil spring 62 that comes into contact with the locking portion 50 is fitted onto the core pin 38, and this coil spring 62 is inserted into the hole 54.
The core pin 38 is inserted through the holes 52 and 54. As shown in FIG. 4, the cam-shaped hole 56 has an inverted oval cross section, and has a curved surface 63 with a large curvature and a small curvature on the lower side of the curved surface 63. It consists of a curved surface portion 64 formed as shown in FIG.

The core pin 38 and the connecting rod 42 extend on the same straight line, and a square columnar body 66 is integrally formed at one end of the connecting rod 42 and is slidably fitted into the locking hole 48 of the core pin 38. Ru. Said columnar 6
A pin storage hole 68 is bored in the vicinity of the base of the connecting rod 42 and extends in a direction perpendicular to the axial direction of the connecting rod 42. The stopper pin 40 is slidably inserted. In this case, the length of the stopper pin 40 is selected to be shorter than the diameter of the portion of the connecting rod 42 where the pin storage hole 68 is bored. A relatively long square columnar body 70 is formed at the other end of the connecting rod 42, and a flange portion 72 is formed at the base of this columnar body 70.

A coil spring 74 is fitted onto the connecting rod 42 having such a structure so as to come into contact with the flange portion 72, and the connecting rod 42 is inserted into the cam-shaped hole with the stopper pin 40 inserted into the pin storage hole 68. 56, and inserted into the holes 58 and 60. In this case, the columnar body 66 of the connecting rod 42 is connected to the core pin 38.
The stopper pin 40 is inserted into the locking hole 48, and the stopper pin 40 descends within the pin storage hole 68 under the action of gravity and comes into contact with the lower part of the cam-shaped hole 56 (see FIG. 2a). Further, the coil spring 62 has a hole 52,
54 and the locking part 50,
Similarly, the coil spring 74 also has holes 58 and 60.
is compressed between the stepped portion and the flange portion 72.

On the other hand, the rotational force transmission means 44 includes a belt 76 that engages with a motor (not shown) serving as a rotational drive source, and a pulley 78 that rotates as the belt 76 moves.
and a pulley shaft 80. The motor is for rotating the core pin 38 and the connecting rod 42 a predetermined number of times, and is substantially provided with a control mechanism (not shown) for controlling the rotational drive of the motor. The control mechanism includes, for example, a cam, a limit switch, a counter, etc. that are interlocked with the motor to detect the rotation speed, and when a predetermined rotation speed is reached, an electromagnetic brake is used to stop the motor. It is possible to adopt a mechanism that stops the drive.

Plate bodies 84 and 86 extending in parallel with a spacer 82 in between are integrally fixed to the end face of the first mold 24 using bolts 88. Said plate body 8
Holes 90 and 92 are bored in the holes 90 and 92 in the direction extending the hole 60 of the first mold 24, and the columnar body 7 of the connecting rod 42 is inserted into these holes 90 and 92.
0 is inserted. Further, an annular rod stopper 94 is fitted into the hole 90 of the plate 84.

The pulley shaft 80 has a hole 96 having a square cross section.
is formed in this hole 96, and a columnar body 70 is formed in this hole 96.
are inserted so that they are slidably fitted. Further, the pulley 78 is externally fitted onto the pulley shaft 80, and in this case, the pulley 78 and the pulley shaft 80 are integrated by fitting the key 98. Further, both ends of the pulley shaft 80 are held by bearings 100a and 100b fitted into holes 90 and 92. Note that ring-shaped spacers 102a, 102b, 10 are provided on both sides of the bearings 100a, 100b.
4a and 104b are attached.

Furthermore, the molding device including the mold 22 is provided with an extrusion mechanism 106 for releasing the molded product. This extrusion mechanism 106 includes two extrusion plates 108a and 108b joined to each other, and extrusion plate 108a.
and an extrusion pin 110 implanted in the extrusion plate 1.
A cylinder mechanism (not shown) is connected to 08b. In this case, the extrusion pin 110 is
The extrusion pin 110 is inserted into the holes 112 and 114 formed in the holes 112 and 114 formed in the first mold 24, the plate body 30, and the through hole 116 formed in the third mold 32. It reaches the end face portion on the cavity 36 side.

The thread forming mechanism according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, when manufacturing a molded product, as shown in FIG. 2a, the first mold 24 and the second mold 26 are brought into pressure contact and clamped to define a cavity 36.
In this case, the screw type 46 of the core pin 38 protrudes into the cavity 36, and the stopper pin 40, which enters the cam-shaped hole 56 from the pin storage hole 68, is used for the springing of the coil springs 62 and 74. The cam-shaped hole 56 is pressed downward in the direction of arrow B.
The hole portion 58 is in contact with the stepped portion substantially forming the hole portion 58. In such a mold-clamped state, molten metal, that is, molten resin, is injected into the cavity 36 at a relatively high injection pressure via a flow path (not shown). As a result, the molten resin filled in the cavity 36 presses the core pin 38 in the direction of arrow B, but the locking portion 50 of the core pin 38 is connected to the connecting rod 42 locked by the stopper pin 40.
is in contact with. Therefore, the position of the core pin 38 does not shift.

After the injection process for filling the cavity 36 with molten resin is completed, the molten resin cools and solidifies as the molding progresses, forming the molded product 120 (see Fig. 2b).
reference).

Next, a motor (not shown) is driven and its rotational force is transmitted to the pulley 78 via the belt 76. This causes the pulley 78 to rotate in the direction of arrow A. As a result, the pulley shaft 8 is integrated with the pulley 78.
0 rotates, and the connecting rod 42 fitted into the hole 96 of the pulley shaft 80 rotates in the direction of arrow A. At this time, the stopper pin 40 is displaced while slidingly contacting the cam-shaped hole 56. That is, as shown in FIG. 4, the stopper pin 40 rotates in the direction of arrow A and is displaced along the curved surface 64 on the lower side of the cam-shaped hole 56. Therefore, the stopper pin 40 is in sliding contact with the cam-shaped hole 56 in the pin storage hole 68.
When the connecting rod 42 is rotated approximately 90 degrees from its original position, the stopper pin 40 is completely accommodated within the pin receiving hole 68, as shown in FIG. By storing the stopper pin 40 in the pin storage hole 68 in this manner, the stopper pin 40 is removed from the step between the cam-shaped hole 56 and the hole 58, so that the locked state of the connecting rod 42 is maintained. When released, the connecting rod 42 is displaced in the direction of arrow B by the elastic force of the coil spring 74 (see FIG. 2b). At this time, the base side of the columnar body 66 of the connecting rod 42 is connected to the locking hole 48 of the core pin 38.
While the columnar body 70 is pulled out from the inside, the columnar body 70 is pulled out from the pulley shaft 8.
0, and the flange portion 72 comes into contact with the rod stopper 94. In this case, the columnar body 6
The distal end side of the core pin 38 is not removed from the locking hole 48, and the fitted state between the core pin 38 and the connecting rod 42 is maintained.

Further, the rotation of the connecting rod 42 in the direction of the arrow A continues, and as a result, the core pin 38 is rotated in the direction of the arrow A.
In order to rotate in the direction, the screw mold 46 screws around the female screw 122 formed in the molded product 120. As a result, the screw mold 46 is removed from the female screw 122, the core pin 38 is displaced in the direction of arrow B by the elastic force of the coil spring 62, and the locking portion 50 and the connecting rod 42 come into contact (second (see figure c). Then, the drive of the motor (not shown) is stopped so that the pin storage hole 68 extends substantially vertically. Note that the drive is stopped by the control mechanism (not shown).

Next, the first mold 24 and the second mold 26 are separated and opened. Thereafter, by driving a cylinder mechanism (not shown) connected to the push-out plate 108b, the push-out plates 108a and 108b are displaced to the positions indicated by the two-dot chain lines. As a result, the ejector pin 1
10 protrudes from the third mold 32 in the direction of arrow D and extrudes the molded product 120. Furthermore, when the extrusion plates 108a and 108b are displaced in the direction of arrow D,
The pushing plate 108a presses the columnar body 70 of the connecting rod 42, thereby displacing the connecting rod 42 and the core pin 38 to a position further in the direction of arrow D than the initial position shown in FIG. 2a. Then, the stopper pin 40 housed in the pin housing hole 68 descends due to gravity, enters the cam-shaped hole 56, and comes into contact with the curved surface 64 (see FIG. 4). Thereafter, the extrusion plates 108a, 108b and the extrusion pin 110 are returned to their original positions. As a result, the core pin 38 returns to its original position due to the elastic force of the coil springs 62 and 74, and the stopper pin 40 abuts against the step between the cam-shaped hole 56 and the hole 58, and the core pin 38 is positioned. Ru. That is, when the core pin 38 is removed from the molded product 120 and then returned to its original position, the core pin 38 is simply linearly displaced and locked without being twisted.

In addition, in this embodiment, a male screw type 4 is used.
6 is used to form the female screw 122, but it is easily understood that by changing the screw type to a female screw type, it becomes possible to form a male screw in the molded product. .

According to the present invention, as described above, by effectively utilizing the fall of the stopper pin fitted into the connecting rod due to gravity and the displacement of the stopper pin due to the sliding action with the cam-shaped hole, the connecting rod It becomes possible to position and release the positioning of the core pin for forming the threaded portion that engages with the core pin. That is, when positioning the core pin, the stopper pin is displaced so as to protrude from the connecting rod,
The core pin is positioned under the locking action of the stopper pin and the cam-shaped hole. Therefore, the core pin is not displaced by the pressure of the molten metal filled into the cavity, and it is possible to form a desired screw. Further, the locked state of the core pin can be easily released by simply rotating the connecting rod. Further, when the core pin is removed from the screw of the molded product and then returned to its original position in order to wait for the next molding process, there is no need to screw the core pin as in the conventional case. , therefore,
The time required for the return operation of the core pin can be shortened, and as a result, it is possible to achieve the effect that production efficiency can be improved.

Although the present invention has been described above with reference to a preferred embodiment, the present invention is not limited to this embodiment. Of course, various improvements and changes in design are possible without departing from the gist of the present invention, such as being able to be configured to be connected.

[Brief explanation of the drawing]

1a and 1b are partially omitted cross-sectional views of a mold part of a molding device for explaining a method of molding a threaded portion according to the prior art, and FIG. FIG. 2b is a partially omitted vertical sectional view of the incorporated molding device, and FIG. A partially omitted vertical cross-sectional view showing the state in which the core pin in the thread forming mechanism of Fig. 2b is detached from the molded product, Fig. 3 is a cross-sectional view taken along the - line shown in Fig. 2a, and Fig. 4 is a cross-sectional view taken along the line shown in Fig. 2a. Shown in −
5 is a cross-sectional view taken along the - line shown in FIG. 2b. 20...Thread part forming mechanism, 22...Mold, 36...
... Cavity, 38 ... Core pin, 40 ... Stopper pin, 42 ... Connection rod, 44 ... Rotational force transmission means, 56 ... Cam-shaped hole, 68 ... Pin storage hole, 106 ... Extrusion mechanism, 120...molded product.

Claims (1)

[Claims for Utility Model Registration] (1) A core pin having a threaded tip facing the cavity; a connecting rod connected to the core pin; A stopper pin that is slidably inserted into a pin storage hole drilled in the connecting rod, a cam-shaped hole into which the stopper pin enters, and a rotational drive that is connected to the connecting rod via a rotational force transmission means. and a pressing means for pressing a connecting rod integral with the core pin toward the core pin, the core pin is locked when the stopper pin enters the cam-shaped hole, and the core pin is locked when the stopper pin enters the cam-shaped hole, and the core pin is locked when the stopper pin enters the cam-shaped hole, and By rotating the connecting rod under driving action and storing the stopper pin in the pin storage hole under sliding action with the cam-shaped hole, the locked state of the core pin is released and the core pin is removed. A screw part forming mechanism characterized in that the core pin is removed from the molded product while being screwed, and after the molded product is taken out from the mold, the core pin is returned to its original position under the pressing action of the pressing means. . (2) In the mechanism described in claim 1 of the utility model registration claim, the stopper pin stored in the pin storage hole can enter the cam-shaped hole, and when the core pin is sent out by the pressing means. A thread forming mechanism that moves downward by gravity within the pin storage hole and enters the cam-shaped hole. (3) Utility model registration In the mechanism described in claim 1, the core pin and the connecting rod extend on the same straight line, and the first elastic member that presses the core pin in the direction of storing it in the mold is A second elastic member that is engaged with the core pin and presses the connecting rod in the same direction as the above-mentioned direction is engaged with the connecting rod, and the connecting rod and the core pin are connected so that the connecting rod is pressed against the core pin. A threaded part forming mechanism that can be moved forward and backward. (4) Utility Model Registration In the mechanism described in claim 1, the pressing means is a screw forming mechanism consisting of a reciprocating extrusion plate that constitutes an extrusion mechanism for releasing the molded product from the mold.