KR101591892B1

KR101591892B1 - Casting mold for piston

Info

Publication number: KR101591892B1
Application number: KR1020150107964A
Authority: KR
Inventors: 최정훈
Original assignee: 최정훈
Priority date: 2015-07-30
Filing date: 2015-07-30
Publication date: 2016-02-04

Abstract

The present invention relates to a method of forming a comb tooth on one surface or both surfaces of a branch path of a side mold when simultaneously casting two pistons through a single mold assembly to easily separate and mold the semi-finished product of the cast- And can improve the accuracy of the piston by separating and finishing the piston from the semi-finished product using a machining center, an MCT, a computer application processing, a CNC, a lathe, and the like.
In order to achieve the above object, a piston-casting mold forming apparatus according to the present invention comprises a molten metal injection unit, a branch connected to the molten metal injection unit, And a side mold including a groove portion, wherein the branch furnace is formed with a comb groove on one surface or both surfaces thereof.

Description

[0001] CASTING MOLD FOR PISTON [0002]

The present invention relates to a method of forming a comb tooth on one side or both sides of a branch of a side mold when the two pistons are simultaneously cast through a single mold assembly to easily separate and mold the semi-finished product of the cast- And can improve the accuracy of the piston by separating and finishing the piston in the semi-finished product using a machining center, an MCT, a computer application processing, a CNC, a lathe, and the like.

Generally, an engine is a typical internal combustion engine that obtains power by introducing air and fuel into a combustion chamber and burning it.

A piston which reciprocates at a high speed due to the combustion of fuel is installed inside the cylinder of the engine. The installed piston receives the pressure of the high temperature and high pressure combustion gas generated in the combustion chamber and rotates the crankshaft through the connecting rod.

Such a piston is formed by casting a molten metal such as aluminum by injecting a molten metal into a piston casting mold forming apparatus and naturally solidifying it. The piston is continuously exposed to a harsh environment such as high temperature and high pressure, In addition, it requires the highest precision.

As a conventional technique for casting such a piston, there is disclosed in Japanese Patent Application Laid-Open No. 10-2011-0076740 (issued on Aug. 31, 2011) "piston manufacturing mold of vehicle engine".

The above prior art is composed of an upper mold for molding the head portion of the piston, a core mold for conditioning the space of the lower and lower portions of the piston, and two side molds for molding the cylinder portion of the piston.

However, in general, the mold apparatus according to the prior art is manufactured by processing the mold base of SKD6 type and the lump shape due to the durability problem of the mold,

In order to improve the precision, it is necessary to process the mold by using all the various machining methods such as milling, wire, discharge, grinding, and lapping, and also manual machining and manual line machining must be performed. Therefore, However,

Even if the machining of the mold apparatus is completed, only one piston is cast for each mold apparatus, resulting in a problem that the productivity is lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a mold for casting a piston casting mold by dividing the mold into a plurality of molds for easy machining,

Two piston forming spaces are provided in one side mold, and two pistons are cast by one injection of molten metal to improve the productivity of the piston. After machining the piston in the semi-finished product, the machining center, MCT, It is an object of the present invention to provide a piston casting mold forming apparatus which can improve the precision of a piston by performing various types of grinding using application machining, CNC, and a lathe.

It is another object of the present invention to provide a piston-casting die molding apparatus in which a comb-like groove is formed on one or both surfaces of a branch furnace so that a runner-forming section, in which molten metal injected into two molding spaces, .

In addition, the present invention provides a method of manufacturing a metal mold, which is mounted on a mounting hole of an upper mold, which is assembled to an upper opening of a molding space to facilitate discharge of gas including air contained in the molten metal during natural solidification of the molten metal, And a pushing means for preventing the thermoforming ring from separating from the mold. The present invention also provides a molding apparatus for a piston casting mold, comprising: a heat-molding ring having a discharge hole having an inclined structure;

In order to achieve the above object, a piston-casting mold forming apparatus according to the present invention comprises:

The molten metal injection part,

A branch connected to the molten metal injection unit,

And a side mold part connected to both sides of the branch to form an outer side surface of the piston,

The branch path

And comb teeth grooves are formed on one surface or both surfaces.

The piston casting mold forming apparatus according to the present invention comprises:

And an upper mold assembled to an upper opening of the molding space to mold a head surface of the piston,

The upper mold

A mounting hole communicating with the molding space,

A thermoforming ring mounted in the mounting hole and having an exit hole punctured in an oblique-light inclined structure so as to communicate with the molding space,

And a pressing means provided at one side of the fitting hole for pressing the warming-forming ring in the direction toward the molding space.

The mold base can be easily processed and the entire manufacturing time can be shortened by being assembled by dividing and machining one mold assembly into a plurality of molds,

There is provided an effect that the productivity of the piston can be improved by forming two molding spaces in one side mold and casting two pistons at the same time by one injection of molten metal,

In this way, it is possible to precisely process the piston through various machining processes using machining center, MCT, computer application processing, CNC,

By providing the comb tooth groove on one side or both sides of the branch roller, it is easy to separate the runner formed portion, which naturally coagulates on the branch roller, from the side mold and to easily take out the piston.

In addition, the apparatus for molding a casting mold for a piston according to the present invention includes a mounting hole, and a thermoforming ring mounted in the mounting hole and having a vent hole having a tilted structure of a downwardly directed light, is introduced into an upper mold to be assembled in an upper- So,

The molten metal injected into the discharge hole is naturally solidified by the excess forming part, so that the gas including the air contained in the molten metal can be smoothly discharged, thereby preventing defective bubbles generated in the piston,

There is an effect that pressure can be applied to the piston molding which naturally coagulates while introducing a pressing means for pressurizing and fixing the warming-forming ring to prevent the separation of the warming-forming ring.

1 is an assembled sectional view of a piston-casting mold forming apparatus according to the present invention;
2 is an exploded perspective view of a side mold according to the present invention.
3 is a front view of a semi-finished molded article molded by a piston-casting die molding apparatus according to the present invention.
4 is a plan view for explaining the pressing means of the piston-casting die molding apparatus according to the present invention.

While the present invention has been described in connection with certain embodiments, it is obvious that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the drawings, the same reference numerals are used for the same reference numerals, and in particular, the numerals of the tens and the digits of the digits, the digits of the tens, the digits of the digits and the alphabets are the same, Members referred to by reference numerals can be identified as members corresponding to these standards.

In the drawings, the components are expressed by exaggeratingly larger (or thicker) or smaller (or thinner) in size or thickness in consideration of the convenience of understanding, etc. However, It should not be.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the term " comprising " or " consisting of ", or the like, refers to the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

It is to be understood that the first to second aspects described in the present specification are merely referred to in order to distinguish between different components and are not limited to the order in which they are manufactured, It may not match.

In describing the piston-casting die molding apparatus according to the present invention, when a rigid approximate direction reference is specified with reference to FIG. 1 for convenience, the upper, lower, left, and right directions are determined in the direction in which gravity acts, Unless otherwise specified in the description and the claims of the invention relating to the drawings, the directions are specified in accordance with this standard.

Hereinafter, a piston casting mold forming apparatus according to the present invention will be described with reference to the accompanying drawings.

1 which is a sectional view of the mold assembly A, Fig. 2 which is a perspective view of the side mold 10, Fig. 3 which is a front view of the semi-finished product C and Fig. 4 which is a plan view of the side mold 10. Fig. The piston casting mold forming apparatus according to the present invention mainly includes a side mold 10 and a mold assembly A in which the upper mold 20 and the core mold 30 are assembled together.

The side mold 10 is connected to both sides of the branch passage 14 connected to the molten metal injection portion 13 and the molten metal injection portion 13 pierced at the upper center, Side molding space portions 15 and 16 for molding the outer side surfaces of the first and second mold-

The upper and lower molding spaces 15 and 16 are formed to be open at upper and lower portions so that the upper mold 20 and the core mold 30 are assembled to the openings of the respective molding spaces.

The present invention is characterized in that two pistons are cast and formed in the both side molding space parts 15 and 16 through the branch path 14 so that one side mold 10 has two upper molds 20 and two So that the core metal mold 30 is assembled.

The side mold 10 is formed so that the molten metal injection portion 13, the branch passage 14 and the both-side molding space portions 15 and 16 correspond to each other to take out the molded semi-finished product C (I.e., a structure in which the first and second bodies 11 and 12 are separable and assembled), that is, the first body 11 and the second body 12, .

The first and second bodies 11 and 12 are separated and joined together through separate mold opening / closing means (not shown). The mold opening / A cylinder member (not shown) coupled to the other body or a cylinder member coupled to the other body in a state where one body is fixed, and the like.

The molten metal injection portion 13, the branch passage 14 and the both-side molding space portions 15 and 16 are formed in the inner contact surface where the bodies 11 and 12 are in contact with each other. Front and rear left and right surfaces of the part 13, the branch passage 14 and the both-side molding spaces 15 and 16 are sealed to function as a casting for the outer casting molding of the semi-finished product C.

That is, the inner surface of the first and second bodies 11 and 12 surrounding the forming space portions 15 and 16, the bottom surface of the upper mold 20, and the outer surface of the core portion 31, ), And a fitting groove, various bosses and inserts for compression ring and oil ring of the piston, crown, skirt and piston of the piston are formed (the specific construction including the fitting groove of the piston is omitted in FIG. 3). .

A comb tooth groove 14a is formed on one or both surfaces of the branch path 14 formed by combining the first and second bodies 11 and 12.

The comb teeth groove 14a has a structure in which a plurality of grooves formed in a recessed shape in left and right directions are formed in a lattice shape.

The reference numerals 15a and 16a denote shaft members that can be formed into a structure in which a coupling hole P1 through which the piston is engaged with the connecting rod is penetrated.

The upper mold 20 is coupled to a driving means such as a cylinder member and lifted and raised from the upper side of the side mold 10 so that when the first and second bodies 11 and 12 are assembled, The bottom surface of the upper mold 20 has a structure corresponding to the head surface of the piston so that the head surface of the piston is formed.

The upper mold (20) of the present invention

A mounting hole 21 formed to penetrate and communicate with the molding space portions 15 and 16,

A thermoforming ring 22 mounted on the mounting hole 21 and having a discharge hole 22A punctured in an oblique downward optical path to communicate with the molding space 15,

And a pressing means (23) provided at one side of the mounting hole (21) for pressing the thermoforming ring (22) toward the molding space portions (15, 16).

The reason why the warming-up ring 22 having the discharge hole 22A is introduced into the upper mold 20 is that the air contained in the melt is discharged through the discharge hole 22A of the warming- So that the gas can be easily discharged.

That is, when an upper mold having a completely closed structure is introduced, like a conventional piston-casting mold forming apparatus, gas generated as the molten metal solidifies in the molding space is discharged. In order to prevent the gas from being completely discharged to the outside of the mold assembly There arises a problem that bubble defects occur where holes are formed on the surface of the piston due to gas.

In addition, in order to solve the above-mentioned problems in the conventional piston molding machine, it is necessary to map the air vent structure such as the fine grooves into various shapes in the contact surfaces between the respective molds. And it takes a long processing time.

On the other hand, when the upper mold 20 having the same structure as the present invention is introduced, the molten metal filled in the molding spaces 15 and 16 is injected onto the discharge hole 22A, There is an advantage in that the gas can be smoothly discharged using the piston 22A. In the structure of the piston-casting die molding apparatus, there is an advantage that it is not necessary to perform post-machining such as an air vent structure.

This is because, when only one molding space portion is provided, the molten metal injection portion formed on the molding space portion functions as a gas discharge passage, so that even if the air vent structure is simply implemented,

Since the two pistons are simultaneously cast using the branch passage 14 and the two side molding space portions 15 and 16, the molten metal is injected from the lower portion of the molding space portions 15 and 16 on the molten metal injection structure, When the upper portions of the portions 15 and 16 are sealed, it becomes difficult to secure the gas discharge passage, and a large number of air vent structures are required and complicated.

In this case, the thermoforming ring 22 is made of an alloy material excellent in thermal insulation, unlike the other mold parts, and is made of a piston P molded in the molding space portions 15 and 16, a surplus molded in the discharge hole 22A So that the solidification (cooling) times of the molded part 3 are made to be different from each other.

That is, the excess forming portion 3 of the discharge hole 22A is made to coagulate the piston P of the molding space portions 15, 16 at a slower rate of time than the piston P of the molding space portions 15, 16, (3).

In this regard, details of machining the excess forming portion 3 solidified in the discharge hole 22A by using a machining center, an MCT, a computer application processing, a CNC, a lathe or the like will be described later in detail.

The reason why the heat-insulating molding ring 22 is separately provided and mounted in the mounting hole 21 is that the excess molded part 3, which is shaped like a wedge when the semi-finished molded product C is separated, To prevent the entire mold 20 from being separated from the semi-finished molded product C.

The pressing means 23 is for preventing the heat-generating molding ring 22 from being detached or detached from the mounting hole 21 due to the pressure generated when the molten metal is filled in the discharge hole 22A or natural coagulation is performed ,

And a fixing bar 24 whose one end is in contact with the at least one heat-retaining ring 22 and the other end is engaged with the upper surface of the upper mold 20. [

The fixing bar 24 is coupled to a position corresponding to the height of the warming-up ring 22 by using the nut 25 and the bolt 26 and the fixing bar 24 is rotated by tightening or loosening the bolt 26 Can be fixed.

Reference numeral 21a denotes a mounting ring fixed to the mounting hole 21 and guiding the mounting of the warm-holding ring 22.

The upper mold 20 includes a pair of support bars 27 coupled to the mounting hole 21, a connection bar 28 having both ends thereof coupled to the upper end of the support bar 27, (29) coupled to the center of the second housing (28).

The upper mold 20 of the present invention is different from a general mold structure in that a lifting rod (not shown) of a cylinder member is fastened to the upper mold 20 for lifting and lowering the upper mold 20, 22 and the pressing means 23 are provided so that the binding means 29 can not be directly provided at the center of the upper metal mold 20,

A binding port 29 is provided at the upper center of the upper mold 20 by using the pair of supporting bars 27 and the connecting bar 28 as described above.

At this time, depending on the type of the piston, a depressed portion in the form of a female thread may be formed on the head surface. In this case, since the semi-finished product C can not be separated and taken out when the upper mold 20 is lifted in a straight line, 29 is provided with a tongue-shaped coupling groove 29a, so that the upper mold 20 can be rotated and lifted while the lifting rod is coupled to the coupling groove.

Next, the core metal mold 30 is fixed to a jig (not shown) of a molding apparatus, and when the first and second bodies 11 and 12 are assembled, The core portion 31 protruded upward is assembled into the molding space portions 15 and 16 so that the outer surface of the core portion 31 has a structure corresponding to the inner cavity structure of the piston So that the internal cavity of the piston is formed.

The core mold 30 includes lifting means (not shown) for lifting the core portion 31 individually so that only the core portion 31 can be easily separated from the cavity of the solidified semi-finished product C at this time .

The elevating means may be realized by a cam member (not shown) connected to the core portion 31 and rotating in conjunction with a motor or the like.

Although not shown in the drawings, the cooling passages are formed in the first and second bodies 11 and 12, the upper mold 20 and the core mold 30 of the side mold 10, And communicates with the air inlet port and the air discharge port of the mold, so that air cooling is performed during the casting of the piston.

Hereinafter, the casting and molding of a piston using the piston-casting mold forming apparatus having the above-described configuration and the operation and effect of the present invention will be described.

First, the piston-casting mold forming apparatus of the present invention is characterized in that a core mold 30 is fixedly mounted on a jig (not shown), and first and second end portions of a side mold 10 provided on both sides of the jig, And the upper and lower molds 20 and 20 are fastened to a lifting rod (not shown) of a cylinder member provided at an upper portion of the jig.

In this state, when the first and second bodies 11 and 12 are moved forward by the cylinder member (not shown) toward the core metal mold 30, they are joined to each other so that the molding space portions 15 and 16 The core mold 30 is assembled and the upper mold 20 is lowered by the cylinder member so as to be assembled to the upper opening of the molding space portions 15 and 16 and the core portion 31 is raised So that the molding space portions 15 and 16 are sealed while being inserted into the molding space portions 15 and 16.

Next, the molten metal is injected into the molten metal injection unit 13 in which the nozzle (not shown) of the piston-casting mold-shaping apparatus is assembled.

The molten metal injected into the melt injection section 13 is transferred to the molding spaces 15 and 16 through the branch passage 14 and the molten metal passing through the branch passage 14 flows into the molding space 15, The fluidity is controlled by the comb teeth groove 14a, the flow is controlled, and impurities or oxides contained in the molten metal are filtered.

The molten metal moved to the molding spaces 15 and 16 is filled up from the lower part to the upper part. At this time, the present invention is characterized in that the upper mold 20 has the discharge hole 22A communicated with the molding space parts 15 and 16, The molten metal filled in the molding space portions 15 and 16 is filled up to the discharge hole 22A beyond the molding space portions 15 and 16.

When the molten metal is filled up to the predetermined height of the discharge hole 22A, the injection of the molten metal is stopped, and in this state, the air-cooling means is operated and natural coagulation of the molten metal is performed for a predetermined time (about 3 to 5 minutes).

At this time, the gas contained in the molten metal is discharged to the outside of the mold assembly (A) through the excess forming part (3) due to the structure of the discharge hole (22A)

In this case, a vibrator (not shown) is provided in the opened discharge hole 22A for quick and complete discharge of the gas, so that vibration can be applied to the filled molten metal to accelerate discharge of the gas.

When the natural coagulation of the molten metal is completed while the gas is discharged, the operator rotates the fixing bar 24 of the pressing means 23 to first separate the heating-forming ring 22 from the mold assembly A, It is possible to separate the warming-up ring 22 due to the low-temperature lowering structure of the heat exchanger.

When the cylinder member (not shown) and the elevating means (not shown) of the side mold 10 and the upper mold 20 are sequentially operated, the first and second bodies 11 and 12, the upper mold 20, And the core portion 31 are separated from each other.

At this time, the upper mold 20 having a structure in which the contact area with the molten metal naturally coagulating is apt to be easily released, and the first and second bodies 11 and 12 of the side mold 10, unlike the core portion 31, The contact area between the branch path 14 and the runner forming part 2 is formed in a flat plate shape and the adhesive force between the runner forming part 2 and the branch path 14 is increased The first and second bodies 11 and 12 may not be separated easily,

Since the comb teeth 14a are formed on one or both surfaces of the branch furnace 14, the waste portions 2a corresponding to the comb teeth 14a are formed on one or both surfaces of the solidifying runner forming portion 2 As a result, the first and second bodies 11 and 12 can be easily separated from each other.

3, the semi-finished product C taken out through the separation of the mold assembly A includes a central gate portion 1, a runner molding portion 2 connected to the lower portion of the gate portion 1, a runner molding portion 2) the two pistons P connected to both sides and the excess forming part 3 connected to the upper part of each piston P are taken out in an integrated form.

The semi-finished molded product (C) taken out is cut (cut) into a connecting portion between the two pistons (P) and the runner forming portion 2 and a connecting portion between the two pistons P and the excess forming portion 3, And the surface of the piston P is finished, the casting of the two pistons P is completed.

In this case, it is generally necessary to perform various machining operations such as machining center, MCT, computational application, CNC, and grinding using a lathe, etc., on the entire surface of the casted piston during casting of the piston. , The grinding time for the cutting part of the excess forming part 3 is not different from that of the conventional casting molding machine.

The waterproofness of the mold assembly A is ensured in the mold closing state of the mold assembly A due to the operation of the pressurizing means 40 to be described later during mold closing of the side mold 10 and the mold opening through the mold opening, The first and second bodies 11 and 12 are separated and fixed, and a detailed description thereof will be described later.

In the present invention, when the molten metal injected into the mold assembly A is naturally solidified, the assembly pressure of the entire mold assembly A, that is, the pressure of the side mold 10, the upper mold 20, The mold clamping force is dependent on the mold closing force of the first and second bodies 11 and 12 which are mutually combined. This mold clamping force secures watertightness of the mold assembly A so that the molten metal leaks to the outside of the mold assembly A It is an important factor to prevent

As shown in FIG. 4, the present invention introduces the pressurizing means 40 for holding the first and second bodies 11 and 12 in a mixed state during the solidification of the molten metal, separately from the pressure of the cylinder member.

The pressing means (40) of the present invention

A first connecting piece 41 coupled to a side surface of the second body 12, a second connecting piece 42,

And a coil spring 43 having both ends connected to the first connection piece 41 and the second connection piece 42 to exert an elastic force in a direction in which the first and second bodies 11 and 12 are joined together do.

It is more preferable that the first and second connecting pieces 41 and 42 are provided on both sides of the first and second bodies 11 and 12, respectively.

The first and second connection pieces 41 and 42 coupled to the first and second bodies 11 and 12 may include first and second extension portions 41A and 42B extending in different body directions, And first and second supporting portions 41B and 42B which are laterally bent at the end portions of the first and second extending portions 41A and 42B,

The coil spring 43 exerts an elastic force in a direction opposite to the compression in a state where both ends of the coil spring 43 are coupled to the first and second support portions 41B and 42B.

That is, the first and second connecting pieces 41 and 42 are bent so as to have first and second supporting portions 41B and 42B facing each other and bypassing each other, A coil spring 43 is provided between the two support portions 41B and 42B to exert an elastic force in the direction opposite to the compression.

The reason for introducing the pressing means 40 having the above-

In the case of the coil spring which exerts the elastic force in the compression direction, there is a high possibility that the elastic force is deteriorated due to the extension of the coil spring in the state where the first and second bodies 11 and 12 are separated,

The first and second connecting pieces 41 and 42 which extend and bend in different directions from the corresponding body and the first and second connecting pieces 41 and 42 exert an elastic force in the direction opposite to the compression The elastic force is not lowered due to the compression of the coil spring 43 in a state where the first and second bodies 11 and 12 are separated from each other.

At this time, if a coil spring 43 that exerts an elastic force in the direction opposite to the compression is introduced, there is a problem that the coil spring 43 is folded without being compressed when the first and second bodies 11 and 12 are assembled As a result,

The pressing means 40 of the present invention is a telescopic type in which the coil spring 43 is inserted therein and the both ends thereof are coupled to the first and second supporting portions 41B and 42B to be displaced in length And a support member 44 for supporting the support member.

The support member 44 of the telescopic type is coupled to the tubular bodies having different diameters so as to be continuously inserted so that the entire length thereof can be adjusted. The coil spring 43 is attached to the telescopic type support member 44, Once embedded,

The coil springs 43 that are compressed as the distance between the first and second supporting portions 41B and 42B become narrower as the first and second bodies 11 and 12 are assembled together are restrained by the supporting member 44, The support member 44 guides the extension of the coil spring 43 due to the elastic force even when the first and second bodies 11 and 12 are separated from each other.

The support member 44 of the telescopic type includes an outermost pipe 44A and an outermost pipe 44B disposed at the outermost side in the longitudinal direction of the support member 44. The support member 44 has hook protrusions 44a and 44b,

The first and second support portions 41B and 42B are provided with hook grooves 41a and 42a to which the hook protrusions 44a and 44b are respectively fastened.

Therefore, when the tubular bodies of the telescopic type support member 44 are compressed while being inserted into each other by the separation of the first and second bodies 11 and 12, the ends of the innermost tube 44A and the outermost tube 44B The hook protrusions 44a and 44b are inserted into and engaged with the corresponding hook grooves 41a and 42a while contacting the opposed first and second support portions 41B and 42B.

The first and second bodies 11 and 12 which are pressurized to be combined by the elastic force of the coil spring 43 by the engagement of the hook projections 44a and 44b and the hook grooves 41a and 42a, Lt; / RTI >

At this time, the disengagement of the hook protrusions 44a, 44b and the hook grooves 41a, 42a when the first and second bodies 11, 12 are assembled can be implemented in a forced subtraction manner,

It is preferable that a separate release button (not shown) is provided for forcing the hook protrusions 44a and 44b to the first and second support portions 41B and 42B,

It is preferable that the release button is controlled by interlocking with the combination of the first and second bodies 11 and 12 through electronic control using a solenoid valve or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood that various changes, omissions and substitutions may be made without departing from the spirit and scope of the invention as defined by the appended claims. Substitutions should be construed as falling within the scope of protection of the present invention.

P: Piston C: Semifinished product molding
1: gate part 2: runner forming part
2a: Weight loss part 3: Surplus molding part
10: side mold 11, 12: body
13: molten metal injection part 14:
14a: comb teeth groove 15, 16: forming space part
20: Upper mold 21: Mounting hole
22: discharge hole 23: pressing means
24: fixed bar 25: nut
26: bolt 27: support bar
28: Connection bar 29:
30: core mold 31: core part
40: pressing means 41, 42: connecting piece
41A, 41B: extension part 41B, 42B:
41a, 42b: hook groove 43: coil spring
44: support member 44a, 44b: hook projection

Claims

The molten metal injection part,
A branch connected to the molten metal injection unit,
And a side mold part connected to both sides of the branch to form an outer side surface of the piston,
The branch path
A comb tooth groove is formed on one surface or both surfaces,

And pressing means for holding the first body of the side mold and the second body in a combined state,
The pressing means
A first connecting piece coupled to a side surface of the second body, a second connecting piece coupled to a side surface of the second body,
And a coil spring having both ends connected to the first connection piece and the second connection piece, respectively, and exerting an elastic force in a direction in which the first and second bodies are assembled.

The method according to claim 1,
And an upper mold assembled to an upper opening of the molding space to mold a head surface of the piston,
The upper mold
A mounting hole communicating with the molding space,
A thermoforming ring mounted in the mounting hole and having an exit hole punctured in an oblique-light inclined structure so as to communicate with the molding space,
And a pressing means provided at one side of the mounting hole for pressing the at least one thermoforming ring toward the molding space portion.