JP3498949B2 - Mold release device for blow mold - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold releasing device for a mold for forming a mold such as a core by blowing sand for molding into a cavity of the mold. More particularly, the present invention relates to a mold release device provided with a second pressing pin in addition to a conventional first pressing pin for pressing a blow candle in order to smoothly release a mold. 2. Description of the Related Art As a mold release device for a blow-molding mold, a molding mold is molded by blowing high-pressure air together with resin and the like into a cavity of a mold composed of upper and lower molds. As shown in FIG. 6, the lower pressing plate 10 is provided below the lower mold 2,
An arrangement in which an upper pressing plate 20 is provided above an upper mold 3 is known. A plurality of pressing pins 11 projecting directly above the lower pressing plate 10 penetrate the lower mold 2, and the upper end of the pressing pin 11 is located on the bottom surface of the cavity 4. A plurality of blow holes 5 penetrating to the cavity 4 are formed in the upper mold 3, and a plurality of pressing pins 21 protruding from the lower surface of the upper pressing plate 20 are located right above the respective blow holes 5. [0003] The mold 1 with the upper and lower molds 2 and 3 being clamped.
Is heated, and core molding sand is blown from the blow holes 5 (blowing), and is held and cured for a certain period of time (curing). For example, a core (shell core) 6 as a mold is formed in the cavity 4. Then, a blow candle 7 integral with the core 6 is formed in the blow hole 5. After molding the core 6 and the blow candle 7, the upper pressing plate 20
Is lowered to stop the lowering of the upper pressing plate 20 with the upper ends of the plurality of blow candles 7 being pressed by the lower ends of the plurality of pressing pins 21, so that the core 6 remains in the lower die 2. 3 is opened right above, the upper die 3 is released from the core 6, and at the same time, the blow candle 7 is released from the blow hole 5. After the mold is opened, the lower pressing plate 10 is moved up relative to the lower die 2 to push up the core 6 remaining in the lower die 2 with the pressing pins 11, for example, as shown in FIG. The core 6 with the blow candle is removed from the mold 1. The core 6 molded in this manner is then used to mold the casting after the blow candle 7 is removed and the trace of removal is manually finished. [0004] The opening of the mold as described above is performed by pressing the upper ends of a plurality of blow candles extending right above the core with a pressing pin of an upper pressing plate. It is necessary to keep the child from rising from the lower mold and open the upper mold directly above (or the lower mold directly below depending on the model). Also, in order to reduce the breakage rate of the core during the mold opening operation,
A plurality of blow holes are arranged in a well-balanced manner on the entire upper mold to form a plurality of blow candles on the entire core in a well-balanced manner. It is necessary to keep it pressed by pressure. However, when the core shape is a complicated shape having many large and small irregularities on the upper and lower surfaces and the outer periphery as shown in FIG. 5 and the number of planes on which the blow candle can be set on the upper surface of the core is small, It becomes difficult to arrange a plurality of blow candles on the upper surface in a well-balanced manner, and it is difficult to press the entire core with a pressing pin in a well-balanced manner when the mold is opened, and the core may be damaged more frequently. Further, when the mold is opened, the upper core is formed on the upper mold so that the blow candle can be formed not only on the flat surface of the core upper surface but also on the slope so that the whole core is pressed toward the lower mold with good balance. It is also proposed to set a large number of blow holes. However, blow candles formed on the slope of the upper surface of the core may increase the breakage rate of the core when the mold is opened, for example, by pressing the core with a biased pressing force. There is a problem that it takes a lot of man-hours and time to manually finish the formed traces of blow candle removal, and there is a problem that a large number of blow candles requires a large amount of core material sand and increases the core manufacturing cost. . On the other hand, as a measure for suppressing the core breakage rate at the time of opening the mold, various additives for increasing the strength are added to the sand to be filled in the cavity of the mold, so that the core is made of material. It has also been proposed to increase the strength. However.
When the strength of the core itself is increased in this way, the breakage rate at the time of mold opening decreases, but defects such as gas release marks and the like occur on the core surface when gas is generated from additives etc. at the time of casting of the core. ,
At the time of opening the mold, it is difficult to drop the core sand, which causes problems such as an increase in the heat treatment time. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a mold release apparatus for a blow-molding mold capable of suppressing core breakage when the mold is opened even if the number of blow candles is small. The purpose is to: [0008] In order to achieve the above object, a blow mold releasing mold releasing apparatus according to the present invention is formed between an upper mold and a lower mold. Sand for molding is blown into the cavity through the blow hole of the upper mold, and the upper end of the blow candle is pressed by the first pressing pin of the upper pressing plate disposed above the upper mold at the time of mold release. In the blow-molding mold for molding, a mold pressing shaft disposed vertically movably in a shaft hole formed vertically through the upper mold in parallel with the blow hole, and the mold A closing spring material for urging the pressing shaft upward and closing the lower end opening of the shaft hole at a lower end portion of the mold pressing shaft at all times, and being attached to the upper pressing plate via a cushioning spring material, A second pressing means for pressing the upper end of the mold pressing shaft against the closing spring material at the time of releasing the mold;
A pressing pin , disposed between the upper pressing plate and the cushioning spring material;
A pusher which can be adjusted and moved in the longitudinal direction of the second push pin.
And a pressure adjusting member . As described above, in addition to the conventional mold-releasing press by the blow candle, the mold releasing shaft newly provided on the upper mold is pressed via the spring material so that the mold can be released smoothly without difficulty. Can be. In order to increase or decrease the pressing force of the mold pressing shaft, a pressing force adjusting member is provided between the upper pressing plate and the cushioning spring material, the pressing force adjusting member being adjustable in the longitudinal direction of the second pressing pin. Also, depending on the mold, a vent plug for back pressure degassing may be provided in the upper mold. In this case, the vent plug may be shared by the second pressing pin. By arranging the pressing force adjusting member between the upper pressing plate and the cushioning spring material, the set pressure of the cushioning spring material can be freely changed, so that the on-site adjustment of the pressing force becomes easy and It is also possible to compensate for the sag of the spring material. Further, when a vent plug is also used as the second pressing pin, it becomes possible to produce a more accurate mold at a lower cost together with the back pressure deaeration. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a mold for mold making, and an operation state of main parts thereof is shown in FIGS.
In FIG. 1, unlike FIG. 6, an axial mold pressing shaft 30 is disposed in the upper mold 3 in parallel with the blow hole 5. Further, a second pressing pin 42 is provided on the upper pressing plate 40 disposed above the upper mold 3 in addition to the first pressing pin 41. The mold pressing shaft 32 of the upper mold 3 can be provided in place of some of the blow holes in FIG. The blow holes 7 of the upper mold 3 in FIG. 1 are the same as those in FIG. 6, and the number of the blow holes 7 and the mold pressing shafts 32 in one upper mold 3 are set to a suitable number and the entire mold 6 is arranged in a well-balanced manner. It is formed. Blow hole 7 of upper die 3 and mold pressing shaft 3
2, a first pressing pin 4 is provided on the lower surface of the upper pressing plate 40.
The first and second pressing pins 42 are provided. As shown in detail in FIG. 2, the mold pressing shaft 32 slides up and down in a shaft hole in a cylindrical cylindrical body 31 which is fixed by penetrating from the upper surface of the upper mold 3 to the cavity 4. It is inserted as possible. And the mold pressing shaft 32 is
It is always urged upward by a closing spring member 33 inside. The flange portion 31 a at the upper end of the cylindrical body 31 is disposed flush with the upper surface of the upper mold 3 and is fixed with bolts 34. An inner surface of the cylindrical body 31 is formed of a large diameter portion 31b at an upper end, a middle diameter portion 31c at an intermediate portion, and a small diameter portion 31d at a lower end, and a valve whose diameter is tapered at the lower end of the small diameter portion 31 having the smallest diameter. A receiving surface 31e is formed. The shaft-shaped mold pressing shaft 32 has a cylindrical upper end 3 which is vertically slidably fitted in a large diameter portion 31b of the cylindrical body 31.
2a, a round bar-shaped support portion 32b extending directly below the lower surface center of the upper end portion 32a, and a lower end portion 32c fixed to the lower end of the support portion 32b. The support portion 32b is inserted into the small diameter portion 31d of the cylindrical body 31 so as to be vertically slidable. Lower end 32
c is a substantially conical valve fitted to the valve receiving surface 31e so as to be able to be inserted and removed from directly below, and the lower end 32c is hereinafter referred to as a valve 32c as necessary. The closing spring member 33 of the coil spring is inserted into the annular gap between the support portion 32b and the middle diameter portion 31c while being compressed in the axial direction. The lower end of the closing spring member 33 is elastically engaged with a step 31f between the middle diameter portion 31c and the small diameter portion 31d of the cylindrical body 31, and the upper end is elastically engaged with the lower surface of the upper end 32a of the mold pressing shaft 32. I do. The mold pressing shaft 32 shown in FIG. 2 is in a normal state before the mold is released, and at this time, the mold pressing shaft 32 is
3, the upper end portion 32a receives a spring force in the upward direction, and the spring force causes the tapered upper surface of the valve 32c to move toward the valve receiving surface 31.
e and is held in place by elastic contact. This valve 32
c and the lower end surface of the cylindrical body 31 are flush with each other to form a part of the ceiling surface of the cavity 4, and the upper surface of the upper end portion 32 a of the mold pressing shaft 32 is flush with the upper surface of the upper mold 3. Be one. In this state, when an external force is applied to the upper end portion 32a in a downward direction, the upper end portion 32a descends inside the large diameter portion 31b of the cylindrical body 31, and hits a step 31g between the large diameter portion 31b and the middle diameter portion 31c. Contact and stop. The first pressing pin 41 of the upper pressing plate 40 is shown in FIG.
The first pressing pin 41 presses the upper end of the blow candle 7 of the upper die 3 when the upper pressing plate 40 is relatively lowered with respect to the upper die 3. The second pressing pins 42 are provided one by one directly above the mold pressing shaft 32 of the upper mold 3, and when the upper pressing plate 40 is relatively lowered, the lower end of the second pressing pin 41 is moved to the upper end of the mold pressing shaft 32. Press 32a. The second pressing pin 42 is, for example, an upper pressing plate 40
2, and is supported by a cylindrical case 43 fixed to the upper pressing plate 40 by vertically penetrating it as shown in FIG. The flange 43 a at the lower end of the cylindrical case 43 is fixed to the lower surface of the upper pressing plate 40 with bolts 46. A large-diameter piston portion 42a is fixed to the upper end of the second pressing pin 42,
a is slidably inserted into the cylindrical case 43 up and down,
The lower end of the pressing pin 42 projects below the cylindrical case 43. A pressing force adjusting member 45 is provided in the upper end opening of the cylindrical case 43.
Are screwed, and the second spring member 44 of the coil spring is disposed between the pressing force adjusting member 45 and the piston portion 42a in a state where the second spring member 44 is compressed in the axial direction. The pressing force adjusting member 45 expands and contracts the first spring member 44 by manual rotation with a driver or the like to adjust the pressing force or the protruding length of the spring mold pressing shaft 32. As shown in FIG. 2, the second spring member 44 in a normal state is held in a state of maximum extension in which the piston portion 42a elastically contacts the lower end surface in the cylindrical case 43. The mold releasing operation of the mold for forming a mold shown in FIG. 1 is performed by first pressing the upper pressing plate 40 against the upper mold 3 as in FIG.
Is lowered, the blow candle 7 is pressed, and the mold 6 is pressed toward the lower mold 2 to open the upper mold 3 (in some models, the lower mold 2 is opened first). . It is sufficient that the pressing of the mold at the time of release is continued only from the start of the opening of the upper mold 3 to the opening of about several mm to 10 mm. For this reason, in the state before the mold release shown in FIG. 2, the protrusion length H1 of the lower end of the first pressing pin 41 and the protrusion length H2 of the lower end of the second pressing pin 42 are made different from each other, so that H1> H2.
And the difference δ (= H1−H2) between the two is about 1 to
Set to 3 mm. When the upper pressing plate 40 is lowered directly toward the upper mold 3 in the state shown in FIG. 1, first, the lower end of the first pressing pin 41 is moved to the blow candle 7 of the upper mold 3 because of the relationship of H1> H2.
Abuts the top edge of In this state, the pressing pin 41 slightly bites into the upper surface of the blow candle 7, and the second pressing pin 42 contacts the upper end 32 a of the mold pressing shaft 32. When the upper mold 3 is opened while maintaining this state, the first pressing pin 4
While the 1 is pressing the blow candle 7, the second pressing pin 42 also gradually increases the force pressing the mold pressing shaft 32,
The second pressing pin 42 compresses the closing spring material 33 to compress the cylinder 3
The mold pressing shaft 32 is pressed down with respect to
The lower end of the valve 32c presses the mold 6 and the releasing action of the mold 6 from the upper mold 3 is promoted. FIG. 3 shows the state during the mold release. In the middle of the mold release shown in FIG. 3, the fixed type first pressing pin 41 presses the blow candle 7 with a predetermined pressing force to prevent the mold 6 from floating from the lower mold 2, and the second pressing. The pin 42 presses the mold 6 via the mold pressing shaft 32. The maximum pressing force of the mold by the second pressing pin 42 is substantially the same as the pressing force of the mold by the first pressing pin 41 due to the set pressure of the closing spring material 33 and the buffer spring material 44, and the minimum is limited. It can be freely set up to a small pressing force. Therefore, it is possible to press the entire mold 6 in a well-balanced manner to release the mold, thereby minimizing mold breakage during the release. The second pressing pin 42
Can be increased or decreased by adjusting the set pressure of the buffer spring material 44 by the pressing force adjusting member 45. In the middle of the mold release shown in FIG. 3, the second pressing pin 42 pushes down the mold pressing shaft 32 to about 5 mm with respect to the cylindrical body 31 and then balances the spring forces of the upper and lower spring members 33 and 44. While the mold pressing shaft 32 is further pressed down, the second pressing pin 42 operates to be pushed up against the cylindrical case 43 so as to compress the second spring material 44. Then, when the mold pressing shaft 32 is pressed down in the large diameter portion 31 of the cylindrical body 31 and comes into contact with the step portion 31g, further pressing down is stopped, and thereafter the second pressing pin 42 is moved in the cylindrical case 43. The mold 6 is released as it is pushed up. FIG. 3 shows an initial stage in which the mold 6 is released, in which the balance of mold pressing is regarded as most important. FIG. 4 shows the final stage of demolding after the initial stage. In this final stage, the second pressing pin 42 is held at the fixed position where the inside of the cylindrical case 43 is pushed up with the maximum stroke, and the lower end 32c of the mold pressing shaft 32 projects from the lower end of the cylindrical body 31 with the maximum stroke. Is held. After the final stage of the release shown in FIG. 4, after the mold 6 is taken out, a mold clamping operation for closing the upper mold 3 is performed.
The mold pressing shaft 32 automatically returns to the original normal position by the returning force of the closing spring material 33, and the second pressing pin 42 of the upper pressing plate 40 automatically returns to the original normal position by the returning force of the second spring material 44. I do. FIG. 5A shows a specific example of the mold 6 molded by the mold for molding in FIG. A black circle 8 shown in the mold 6 in FIG. 1 is a portion pressed by the mold pressing shaft 32 on the upper surface of the mold 6, and the pressed portion 8 is not only a flat surface on which a blow candle can be formed, but also slightly inclined. Since the pressing force of the mold pressing shaft 32 can be increased / decreased even in the portion described above, it can be set freely. Therefore, the required minimum number of blow candles 7 are arranged on the upper surface of
By additionally forming the pressing portion 8 at a position that is well-balanced with the arrangement of the mold, the mold 6 can be pressed with a better balance as a whole at the time of release from the mold, thereby suppressing mold breakage. Further, in a mold in which the number of blow holes is forcibly increased, changing some of them to the mold pressing shaft 32 increases the degree of freedom in designing the mold shape, and increases the amount of sand used for the broad candle 7. Therefore, the manufacturing cost of the mold 6 can be reduced. Further, even if the number of the pressing portions 8 formed on the upper surface of the mold 6 is increased, no excessive pressing force acts on the pressing portions 8, so that the pressing portions 8 are not deformed, and the number of finishing steps after the molding of the mold is reduced. Is done. According to the present invention, in addition to pressing the blow candle with the first pressing pin of the upper pressing plate at the time of mold release as in the prior art, a cushioning spring material is applied to the upper pressing plate. Since the upper surface of the mold is released by pressing the upper surface of the mold via the second pressing pin and the mold pressing shaft, the mold is pressed sufficiently for releasing the mold even if the number of blow holes or blow candles is relatively small. The pressure can be applied to the mold without difficulty. In addition, the mold manufacturing cost can be reduced compared to a mold with more blow holes than usual, and the number of finishing man-hours can be reduced by the less traces of blow candle removal, and the entire mold can be balanced. The mold can be released from the upper mold by being pressed well, and the breakage of the mold during the release can be greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a mold according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of FIG. FIG. 3 is an enlarged sectional view of a main part of FIG. 1 at the time of a releasing operation. FIG. 4 is an enlarged cross-sectional view of the main part of FIG. 1 at the end of a releasing operation. FIG. 5A is a perspective view of a mold released by a release device of the present invention, and FIG. 5B is a perspective view of a mold released by a conventional release device. FIG. 6 is a cross-sectional view of a mold for mold making provided with a conventional release device. DESCRIPTION OF SYMBOLS 1 Mold 2 Lower mold 3 Upper mold 4 Cavity 5 Blow hole 6 Mold 7 Blow candle 32 Mold pressing shaft 33 Closing spring material 40 Upper pressing plate 41 First pressing pin 42 Second pressing pin 44 Spring material for buffer 45 Pressing force adjusting member

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22C 15/24

Claims (1)

(57) [Claims] [Claim 1] Sand for molding is blown through a blow hole of an upper mold into a cavity formed between an upper mold and a lower mold, and blown at the time of mold release. In a blow mold mold for molding, wherein an upper end of a candle is pressed by a first pressing pin of an upper pressing plate disposed above an upper die, the blow hole and the blow hole are formed with respect to the upper die. A mold pressing shaft disposed vertically movably in a shaft hole formed through in parallel in the vertical direction, and urges the mold pressing shaft upward, and the lower end of the mold pressing shaft always has A closing spring member for closing the lower end opening; and a buffer spring member attached to the upper pressing plate, and presses the upper end of the mold pressing shaft against the closing spring member when releasing the mold. A second pressing pin, and the second pressing pin, which is disposed between the upper pressing plate and the cushioning spring material,
2. A mold release device for a blow mold, comprising: a pressing force adjusting member capable of adjusting and moving the pressing pin in the longitudinal direction .