KR100421608B1 - Injection Molding System of Forming Products having Undercut on Inside - Google Patents

Abstract

The present invention is capable of injection molding a joint pipe having a large diameter undercut formed by a slide core contracted to a diameter smaller than the inner diameter of the product along the outwardly inclined surface of the main block as the undercut core reciprocating transfer part moves. The present invention relates to an injection molding apparatus for a molded product having an undercut inside which can improve the workability by improving work efficiency and productivity by eliminating a separate post-processing process and also producing a high quality product.

The present invention includes an upper die having an upper cavity, a lower die having a lower cavity formed corresponding to the upper cavity to form the molded article, and inserted into an upper / lower cavity and having an outer diameter smaller than the inner diameter of the molded article when the molded article is taken out. A contracted undercut core, an undercut core reciprocating transfer unit slidably coupled to one side of the lower die top, and coupled along an outer circumference of the undercut core disposed at the upper end of the lower die and moving together with the reciprocating transfer unit undercut when the undercut core moves A stopper for inducing the contraction of the core, a cylindrical core inserted into the upper and lower cavities, and one side of the cylindrical core is characterized by consisting of a fixed undercut core reciprocating transfer unit.

Description

Injection Molding System of Forming Products having Undercut on Inside

The present invention relates to an injection molding apparatus for a molded article having an undercut on the inside, and in particular, the undercut is formed by a slide core contracted to a diameter smaller than the inner diameter of the product along the outward inclined surface of the main block as the undercut core reciprocating transfer part moves. As it is possible to injection mold a large diameter pipe, it is possible to improve the work efficiency and productivity by eliminating the separate post-processing for undercut treatment, and to produce high quality products. An injection molding apparatus for a molded article having an undercut.

In general, sewage pipe joints, which are connected to bent or interconnected parts of sewage pipes according to the terrain and location where a plurality of sewage pipes are buried, are manufactured through post-processing such as heat injection to the product after injection molding or extrusion molding through a mold. Will produce.

As shown in FIG. 1A, the joint pipe 10 includes a movable part 13 capable of rolling contact inside the body 11 so that the mounting pipe 3 can be adjusted within approximately ± 15 ° in preparation for a change in the ground after installation. Is placed.

1B is a cross-sectional view of the body portion 11 and the movable portion 13 forming the fitting pipe 10, respectively, and the sealing member 15 is coupled to the coupling groove 13a formed along the inner peripheral surface of the movable portion. It is.

In this case, the inner circumferential portion of the body portion 11 to which the movable portion 13 having the outer circumference portion is spherical is undercut to have a curved portion so that the outer circumferential portion of the movable portion 13 can turn, and the movable portion 13 In order to engage the seal member 15, the inner circumference has an undercut treatment such as a coupling groove 13a.

By the way, in order to process the undercut of the joint pipe as described above, but after processing, that is, by applying heat to the product produced through the injection molding or extrusion molding step, but in this case, the surface of the joint pipe becomes rough due to heat by post-processing And at the same time, as the precision of the product is lowered, the product quality and work efficiency of the fitting pipe is reduced, and there is a problem that the unit cost of the product increases because an additional post-processing step must be added for the undercut treatment.

In addition, in order to exclude the post-processing as described above, when the injection molding the body portion 11 and the movable portion 13 of the joint pipe is made of a special steel material rich in elastic force in the sliding block coupled to the lower die of the mold, the outer periphery is partially cut Cores (not shown) were combined to process the undercuts of the body portion 11 and the movable portion 13.

In this case, however, it is not easy to process the core itself made of the special steel, and in general, an undercut joint pipe having a diameter of about Ø75 or less is produced using the special steel core, , When it is necessary to process the inner undercut for the joint pipe having a diameter of up to Ø100 to Ø3000 it is not easy to manufacture a core made of special steel with a large outer diameter, there was a problem that the time and cost of repairing the core is increased.

The present invention is to solve the above problems, the object of the large diameter formed undercut by the slide core is contracted to a diameter smaller than the inner diameter of the product along the outward inclined surface of the main block according to the movement of the undercut core reciprocating transfer portion As it is possible to injection molding a joint pipe having an undercut, it is possible to improve work efficiency and productivity by eliminating a separate post-process for undercut treatment, and also to produce a high quality product so that an undercut can be increased to increase the commercial property. It is to provide an injection molding apparatus for a molded article having.

1A and 1B are state diagrams and cross-sectional views showing a molded article having an undercut inside.

2A to 2G are schematic views sequentially showing an operating state of an injection molding apparatus for producing a molded article having an undercut therein according to a first embodiment of the present invention;

3A and 3B are perspective views showing an undercut core that is deformed and deformed according to the operation of the injection molding apparatus according to the first embodiment of the present invention;

4 is a schematic cross-sectional view showing an undercut core of an injection molding apparatus according to a first embodiment of the present invention;

5A is a front view showing a main block of an undercut core according to a first embodiment of the present invention;

5B is a schematic cross-sectional view taken along the line A-A shown in FIG. 5A;

6 is a side view showing a guide block of the undercut core according to the first embodiment of the present invention;

7 is a schematic view showing an injection molding apparatus for producing a molded article having an undercut inside according to a second embodiment of the present invention;

8A and 8B are perspective views illustrating an undercut core contracted and deformed according to the operation of the injection molding apparatus according to the second embodiment of the present invention.

* Description of Signs for Main Parts in Drawings *

10: fitting pipe 11: body part

13: movable part 20,20a: upper die

21: upper cavity 30,30a: lower die

31: lower cavity 50,50a: undercut core reciprocating transfer unit

60,60a: Cylindrical core Reciprocating transfer part 70,70a: Cylindrical core

80: stopper 90: eject pin

400: undercut core 410,410a: main block

420,420a: first piece portion 430,430a: second piece portion

440: Slide block 451: First guide block

452: second guide block 460: gap

471: first insertion groove 472: second insertion groove

481: turning 482: groove

490: protrusion

In order to achieve the above object, the present invention forms an upper cavity for molding a molded article and at the same time an upper die into which the molten synthetic resin is injected into the upper cavity, and a lower portion corresponding to the upper cavity to form the molded article. A lower die having a cavity and moved vertically to open and close with the upper die, and inserted into the cavity to form an undercut inside the molded article from one side of the upper and lower dies, and an outer diameter smaller than the inner diameter of the molded article when the molded article is taken out. An undercut core reciprocating transfer part coupled to the undercut core contracted to have a contraction, and slidably coupled to an upper end side of the lower die in a direction orthogonal to the opening / closing direction of the upper / lower die and having one side of the undercut core fixed to an inner side thereof; The king is disposed above the lower die A stopper for joining along an outer circumference of the undercut core moving with the transfer part to induce contraction of the undercut core when the undercut core moves, and inserted into the cavity to form a cylindrical portion inside the molded part from the other side of the upper / lower dies. And a cylindrical core and an undercut core reciprocating transfer part coupled to the other end of the lower die in a direction orthogonal to the opening and closing direction of the upper and lower dies, and having one side of the cylindrical core fixed to an inner side thereof. An injection molding apparatus for a molded article having an undercut inside is provided.

In addition, the undercut core has a main block having a plurality of inclined surfaces inclined to the other side and one side is fixed to one side of the undercut core conveying portion and the other side is open to the horizontal movement, and the plurality of inclined surfaces of the main block in the longitudinal direction A plurality of sliding blocks each having a plurality of guide blocks correspondingly coupled to each other, and an inclined surface corresponding to the inclined surfaces so as to be in contact with the plurality of inclined surfaces, and slidingly coupled to the plurality of guide blocks, respectively. Configured; When the undercut core movable portion is horizontally moved in one direction after the lower die is vertically moved to open the product to take out the product, the main block moves together with the undercut core movable portion, and at the same time, the sliding block of the lower die As the sliding movement is made in the opposite direction to the moving direction of the main block by a predetermined distance along the inclined surface of the main block with the stopper in contact with the inclined surface of the main block, the outer diameter formed by the sliding core is larger than the inner diameter of the product. Small shrinkage and deformation.

In this case, the slide block has an inclined surface in contact with the inclined surface of the main block, has an inclined surface in contact with the inclined surface of the guide block, and has an inclined surface in the bottom so as to be slidably coupled in one state, and at the same time, the engaging groove is formed along the inclined surface. And a first piece portion having a plurality of pieces, and the same number of pieces as the first piece portion, disposed alternately with the first piece portion on the inclined surface of the main block, and slidably coupled to the guide block. A coupling groove is formed at a bottom thereof, and includes a second piece portion sliding in contact with an inclined surface of the main block at a time difference with the first piece portion through a space portion generated by sliding movement of the first piece portion; The second piece part is provided to form a gap between the guide groove inside the first piece part and the guide block, so that the first piece part slides along the inclined surface of the main block simultaneously with the movement of the main block, and the second piece The part moves in the direction of the center of the main block by the distance corresponding to the gap.

In addition, the slide block is formed in a spherical shape in the initial state of the outer periphery of the tip so as to form an undercut in the shape of a curved portion inside the body of the joint pipe.

In this case, the slide block may be formed along the outer periphery of the tip in the initial state to form a groove-shaped undercut into which the seal member is inserted inside the movable part of the fitting pipe.

Therefore, by eliminating the separate post-processing for the undercut treatment on the inside of the molded article can reduce the number of work, thereby improving the productivity, and also to produce a high-quality product can increase the marketability.

(Example)

2A to 2G are schematic views sequentially showing an operating state of an injection molding apparatus for producing a molded article having an undercut therein according to a first embodiment of the present invention, and FIGS. 3A and 3B are views of the present invention. 1 is a perspective view illustrating an undercut core shrinked and deformed according to an operation of an injection molding apparatus according to an embodiment, FIG. 4 is a schematic cross-sectional view illustrating an undercut core, and FIG. 5A is a main block of an undercut core according to a first embodiment of the present invention. 5B is a schematic cross-sectional view taken along the line AA shown in FIG. 5A, and FIG. 6 shows a side view of the guide block of the undercut core according to the first embodiment of the present invention, respectively.

The configuration of the injection molding apparatus according to the first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In order to injection molding the molded part shown in FIGS. 1A and 1B, that is, the body part 11 of the joint pipe 10 in which the undercut is formed in which the movable part 13 has the curved part inside, the first embodiment according to the present invention first starts. As shown in FIG. 2A, the upper die 20 and the lower die 30 are formed to correspond to each other, as shown in FIGS. 2B and 2G, to form an outer shape of the body portion 11. Are formed respectively.

The lower die 30 is disposed to be movable vertically downward to take out the body portion 11 and a plurality of ejection pins 90 for extracting the body portion 11 at the center portion thereof. The undercut core reciprocating transfer part 50 and the cylindrical core reciprocating transfer part 60 which are movably coupled in the vertical direction and slidably coupled to the upper sides of the lower die 30 are respectively disposed.

The undercut core reciprocating transfer unit 50 and the cylindrical core reciprocating transfer unit 60, respectively, the undercut core 400 and the cylindrical core 70, each side of which is fixedly coupled to the inner reciprocating transfer unit 50, 60 and horizontally moved together with the molten synthetic resin which is disposed inside the upper / lower cavities (21, 31) and injected through the injection hole of the upper die 20 to form the inside of the body portion 11, and In order to set the centering in the initial state, the projection 481 protrudes from the open end of the cylindrical core 70, and the groove 482 into which the protrusion 481 is inserted is formed at the open end of the undercut core 400. have.

At this time, the outer periphery is formed in a spherical shape to form an undercut inside the body portion 11 and the shrinkage deformation so as to be detached from the undercut of the body portion 11 at the same time as the movement of the reciprocating transfer portion (50). The undercut core 400 includes a main block 410, a sliding block 440, and a plurality of first and second guide blocks 451 and 452 as shown in FIGS. 3A to 3B and 4.

One end of the main block 410 is fixed to the undercut core reciprocating transfer part 50 and the other end is opened.At the same time, as shown in FIGS. 4, 5A, and 5B, the main block 410 has a plurality of angles having a predetermined angle from one end to the other end. The first and second inclined surfaces 411 and 412 are symmetrically formed with respect to the center of the main block 410, respectively.

In addition, a plurality of first and second fixing grooves 413 and 414 are formed in the plurality of first and second inclined surfaces 411 and 412 in the longitudinal direction of the main block 410, respectively. Lower ends of the plurality of first and second guide blocks 451 and 452 are fixedly coupled to the two fixing grooves 413 and 414, respectively.

In this case, the slide block 440 is formed in a spherical shape in the initial state as the outer peripheral end as shown in Figure 3a to form a curved portion (11a) inside the body portion 11 of the fitting pipe as shown in Figure 1b.

In addition, in the sliding block 440, four first piece portions 420 and four second piece portions 430 are alternately disposed on the first and second inclined surfaces 411 and 412 of the main block, respectively, as shown in FIG. 4. First and second insertion grooves 471 and 472 are formed at outer peripheries of the rear ends of the first and second piece portions 420 and 430, respectively, through which the stoppers 80 disposed on the lower die 30 are inserted.

When the first piece portion 420 is slid in the open end direction of the main block 410 along the first inclined surface 411 in contact with the first inclined surface 411 inward, as shown in FIGS. 2A and 3A. The first inner inclined surface 423 is formed at an angle corresponding to the inclination angle of the first inclined surface 411 so that the outer diameter of the undercut core 400 in the initial state is contracted and deformed as shown in FIGS. 2E and 3C to have a small outer diameter. Equipped.

In addition, a first guide groove 421 is formed on the first inner inclined surface 423 to which an upper portion of the first guide block 451 is slidably coupled.

Meanwhile, the second piece portion 430 may slide in the open end direction of the main block 410 along the second inclined surface 412 in contact with the second inclined surface 412 similarly to the first piece portion 420. 2A and 3A, the outer diameter of the undercut core 400 in the initial state is contracted and deformed as shown in FIGS. 2E and 3C to have a small outer diameter, which is formed at an angle corresponding to the inclination angle of the second inclined surface 412. A second inner inclined surface 433 is provided.

In addition, similarly to the first inner inclined surface 423, the second inner inclined surface 433 is formed with a second guide groove 431 in which an upper portion of the second guide block 452 is slidably coupled thereto. 2, the guide groove 431 opens the second guide block 452 and the predetermined gap 460 as shown in FIG. 4 so that the second piece 430 slides at a predetermined time difference from the first piece 420. It is formed to have.

That is, as the main block 410 moves horizontally, the first piece portion 420 slides along the first inclined surface 411 of the main block 410 by the stopper 80 in the vertical and horizontal directions. At the same time, the second piece portion 430 operates in the vertical direction by the distance of the gap 460 so that the first piece portion 420 slides along the inclined surface prior to the second piece portion.

In addition, the first piece portion 420 and the second piece portion 430 may have a pair of first side inclined surfaces 425 and a second side having a predetermined angle such that both sides thereof contact each other for smooth sliding movement. The inclined surface 435 is formed.

Meanwhile, as illustrated in FIG. 2A, the cylindrical core 70 having one side fixed to the cylindrical core reciprocating transfer part 60 and the other opened is formed to have a cylindrical shape with the other side extending to one side where an undercut of the body portion 11 is formed. Formed.

The operation and effects of the injection molding apparatus according to the first embodiment of the present invention formed as described above are described in detail.

First, as shown in FIG. 2A, the first and second dies 20 and 30 are closed in an initial state, and the undercut core 400 and the cylindrical core 70 are disposed in the upper and lower cavities 21 and 31. Are respectively disposed, the molten synthetic resin is injected through the hopper 23 and the injection port 25 formed in the upper die 20 to form the body portion 11 of the joint pipe.

Subsequently, as shown in FIG. 2B, the lower die 30 is moved downward by a distance in which the pair of reciprocating transfer parts 50 and 60 are slidably moved in the horizontal direction, thereby allowing the upper and lower cavities of the upper and lower dies 20 and 30 to move. Open (21, 31).

Subsequently, in order to separate the undercut core 400 disposed in the undercut inside the body portion 11 from the undercut of the body portion 11 as shown in FIG. Move horizontally along the top.

In this case, the main block 410 of the undercut core moves in a horizontal direction together with the undercut core reciprocating transfer part 50, and the first piece part 420 of the sliding block 440 is vertically moved by the stopper 80. As the stopper 80 is moved away from the first insertion groove 471 and moves along the inclined surface as it moves to the second piece portion 430 is a continuous horizontal movement of the main block 410 The stopper 80 is fixed in the state inserted into the second insertion groove 472 until the gap 460 formed between the second guide groove 431 and the second guide block 452 disappears.

Subsequently, as shown in FIG. 2D, the cylindrical core reciprocating is performed while the second piece portion 430 maintains the stopper 80 being removed from the second insertion groove 472 following the first piece portion 420. While the sending part 60 moves in the other direction, the cylindrical part 70 slides along the body part 11 of the fitting pipe.

Thereafter, the first and second piece portions 420 and 430 slide along the first and second inclined surfaces 411 and 412 of the main block 410 by a predetermined distance, as shown in FIGS. 2E, 3B and 4. (11) Reduced and deformed smaller than the inner diameter of the inner undercut.

Accordingly, as shown in FIG. 2F, the undercut core reciprocating transfer unit 50 and the cylindrical core reciprocating transfer unit 60 have a preset limit along the upper portion of the lower die 30, that is, the undercut core (from the inside of the body portion 11). 400 and the cylindrical core 70 is moved to a distance that can be separated.

After the undercut core 400 and the cylindrical core 70 is completely separated from the inside of the body portion 11, a plurality of eject pins 90 are operated in the upward direction as shown in Figure 2g to operate the body portion 11 In order to eject the product again, the molding apparatus is set to an initial state, and this process is repeated to mass produce the body part of the fitting pipe.

On the other hand, Figure 7 is a schematic view showing an injection molding apparatus for producing a molded article having an undercut on the inside according to a second embodiment of the present invention, Figures 8a to 8c is a view of the injection molding apparatus according to a second embodiment of the present invention A perspective view showing an undercut core that shrinks and deforms with operation.

First, the injection molding apparatus according to the second embodiment of the present invention injection molding the movable part 13 inserted into the undercut inside the body part 11, and its configuration is shown in FIG. 7 as the upper and lower dies 20a and 30a, Cylindrical core 70a, undercut core 400a, and cylindrical core reciprocating portion 60a and undercut core reciprocating portion 50a for slidingly moving the cylindrical core and the undercut core are composed of the present invention. It is the same as the injection molding apparatus according to the first embodiment of.

However, the undercut core 400a has the outer peripheral surfaces of the first and second piece portions 420a and 430a constituting the slide block 440a excluding the main block 410a as shown in FIGS. 8A and 8B, as shown in FIG. 1B. As formed to correspond to the inner shape of the movable portion, the outer circumferential shape of the undercut core 400 shown in the first embodiment is different, and its operation method is the same as that of the undercut core 400.

In particular, the slide block 440a of the undercut core is formed along the tip outer circumference in an initial state as shown in FIG. 8A to form a recess 13a into which the seal member 15 is inserted inside the movable part 13 of the fitting pipe as shown in FIG. 1B. The protrusion 490 is formed.

The present invention is applied to the connection pipe of the sewage pipe, but of course, it is also possible to apply to all the case of the injection molded in the connection pipe, such as gas pipes, water pipes and electrical wiring pipes.

In the present invention described above, therefore, by eliminating the separate post-processing for the undercut treatment on the inside of the molded article, it is possible to reduce the labor and thereby improve the productivity, and also to produce high-quality products, thereby increasing the merchandise. There is an advantage to that.

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention. Various changes and modifications will be possible by those who have the same.

Claims (5)

An upper die which forms an upper cavity for molding a molded article and is injected with molten synthetic resin into the upper cavity; A lower die having a lower cavity corresponding to the upper cavity and moving in a vertical direction to open and close the upper die to form the molded article; An undercut core inserted into the cavity to form an undercut inside the molded article from one side of the upper / lower die and contracted to have an outer diameter smaller than the inner diameter of the molded article when the molded article is taken out; An undercut core reciprocating transfer part coupled to an upper end of the lower die in a direction orthogonal to an opening and closing direction of the upper and lower dies, and having one side of the undercut core fixed to an inner side thereof; A stopper disposed on an upper end of the lower die and coupled along an outer circumference of the undercut core moving together with the reciprocating transfer part to induce contraction of the undercut core when the undercut core moves; A cylindrical core inserted into the cavity to form a cylindrical portion inside the molded article from the other side of the upper and lower dies; The inner side of the lower die is composed of an undercut core reciprocating transfer unit coupled to the other side of the upper die and slidably in a direction orthogonal to the opening and closing direction of the upper die and fixed to one side of the cylindrical core on the inner side. Injection molding apparatus for a molded article having an undercut. The main block of claim 1, wherein the undercut core is fixed to one side of the undercut core conveying part and the other side is open, and the outer peripheral part has a plurality of inclined surfaces inclined to the other side to allow horizontal movement; A plurality of guide blocks correspondingly coupled to the plurality of inclined surfaces of the main block along the longitudinal direction, respectively; An inclined surface corresponding to the inclined surface to slide in contact with the plurality of inclined surfaces, the plurality of sliding blocks being slidably coupled to the plurality of guide blocks, respectively; When the undercut core movable portion is horizontally moved in one direction after the lower die is vertically moved to open the product to take out the product, the main block moves together with the undercut core movable portion, and at the same time, the sliding block of the lower die As the sliding movement is made in the opposite direction to the moving direction of the main block by a predetermined distance along the inclined surface of the main block with the stopper in contact with the inclined surface of the main block, the outer diameter formed by the sliding core is larger than the inner diameter of the product. Injection molding apparatus for a molded article having an undercut on the inside, characterized in that the shrinkage deformation small. According to claim 2, The slide block is provided with an inclined surface in contact with the inclined surface of the main block and having an inclined surface in contact with the inclined surface of the guide block provided with an inclined surface on the bottom to be slidably coupled in one state and at the same time the inclined surface A first piece portion consisting of a plurality of pieces having a coupling groove along; Comprising the same number of pieces as the first piece portion and is disposed on the inclined surface of the main block and alternately arranged with the first piece portion, a coupling groove is formed on the bottom surface to be slidably coupled to the guide block, the first piece A second piece part sliding in contact with an inclined surface of the main block at a time difference from the first piece part through a space part generated by sliding of the part; The second piece part is provided to form a gap between the guide groove inside the first piece part and the guide block, so that the first piece part slides along the inclined surface of the main block simultaneously with the movement of the main block, and the second piece The injection molding apparatus of the molded article having an undercut on the inside, characterized in that the portion is moved in the direction of the center of the main block by a distance corresponding to the gap. 3. The injection molding apparatus of claim 2, wherein the slide block is formed in a spherical shape at an initial state so that the outer periphery of the tip forms a spherical undercut of the inside of the body of the joint pipe. 3. The injection molding of the molded article having an undercut therein according to claim 2, wherein the slide block has a protrusion formed along the outer periphery of the slide block in an initial state so as to form a groove-shaped undercut into which the seal member is inserted inside the movable part of the fitting pipe. Molding apparatus.