RU145021U1 - PRESS FORM FOR PRESSURE CASTING - Google Patents

Abstract

1. A mold for injection molding, containing a fixed detachable part and a movable detachable part, made with the possibility of its direct and reverse motion and with a variable-volume cavity located in it, in which a sign in the form of a piston mating with its surface is located and equipped with at least one rod, and the sign is made with the possibility of its direct course under the action of the melt injected through the fixed part, and with the possibility of extracting the casting formed in the forming cavity p IG Petritskaya portion, characterized in that the token is adapted to extract the direct casting during chasti.2 movable split. The mold according to claim 1, characterized in that the piston surface and the surface of the forming cavity mating with it are different from the cylindrical shape. The mold according to claim 1, characterized in that at least one recess is made in the end face of the sign on the piston side. 4. A mold according to claim 1, characterized in that at least one recess is made in its detachable fixed part. The mold according to claim 1, characterized in that the detachable movable part of the mold is assembled from at least two halves. The mold according to claim 1, characterized in that a pusher is passed through the rod and piston. 7. The mold according to claim 1, characterized in that the piston is spring-loaded. The mold according to claim 1, characterized in that the forming cavity is in communication with a source of compressed air. The mold according to claim 1, characterized in that the rod is covered by friction elements of the brake mechanism.

Description

The utility model relates to foundry for the production of products, mainly from thermoplastic polymer injection molding, mainly thick-walled products. The technical solution of the invention can also extend to the receipt of products from other materials.

Known mold for injection molding [2], containing detachable parts, in one of which a forming cavity is made and an ejector is located, and the nozzle is made in the other.

However, the disadvantage of the analogue [1] is that using such a mold it is impossible to obtain thick-walled products of good quality without sinks, without gas and shrinkage porosity. The fact is that with the help of a casting machine, the material is melted through the nozzle of the mold, which determines its laminar (jet) flow when filling the forming cavity (in the case of casting thick-walled products). As a result, the negative effect of the “free stream” is formed, “cold junctions” appear in boundary flows close to the surface of the forming cavity, and the likelihood of formation of gas and shrinkage porosity and shells increases. In addition, a negative “diesel effect” may also occur, accompanied by the explosion of a mixture of melt vapor and displaced air in the forming cavity to produce an unwanted burn in the manufactured product and on the surface of the forming cavity. All this reduces the efficiency of the mold.

A more efficient injection mold [2], adopted as a prototype of a utility model.

It contains movable and fixed detachable parts. Moreover, a nozzle is made in the fixed detachable part, and a forming cavity with a variable volume is made in the movable detachable part. In such a forming cavity, a sign is arranged in the form of a piston equipped with two rods with a support platform, which is connected to a sign movement drive. Moreover, it is made with the possibility of its direct movement under the action of a melt injected through the nozzle of the fixed part and with the possibility of its reverse movement under the action of a servo to move the sign. Therefore, the movable sign also performs the function of an ejector of the casting obtained in this mold after solidification in the forming cavity of its movable part of the injected melt.

This embodiment of the forming cavity and the use of a movable sign for this purpose in the prototype [2] is aimed at providing the possibility of creating a kind of initial barrier (movable partition) for the formed laminar stream of the melt supplied through the nozzle, in order to prevent the spread of negative effects formed in the case of using a press -forms by analogy [1]. Performing as a sign of the piston with its location in the forming cavity contributes to the gradual filling of the resulting variable volume of the cavity with the melt.

However, such a mold for injection molding [2] has a design complexity, since a special drive for moving it is required to perform the movement of the movable sign. This also complicates the manufacture and use of the injection mold.

Another disadvantage of the prototype [2] is the lack of preservation of the quality of the casting, since it, being pushed out of the mold of this design, can change the geometry by moving the volume of the non-solidified material inside. As a result, for example, a thickening of the surface of the casting of a cylindrical shape along its diameter from the side of the gate) will be formed.

Therefore, the objective of the utility model is to obtain a technical result to simplify the design of the mold for injection molding, which will also facilitate the simplification of its manufacturing technology, application and improve the quality of castings.

The problem is solved in that the mold for injection molding (Fig. 1), containing a fixed detachable part 1 and a movable detachable part 2, made with the possibility of its forward and reverse motion, and with a forming cavity 3 of variable volume located in it , in which there is a sign in the form of a piston 4, mating with its surface and provided with at least one rod 5, and the sign is made with the possibility of its direct course under the action of the melt injected through the fixed part 1, and with the possibility of extraction the casting formed in the forming cavity 3 of the movable part 2 has a distinctive feature: the sign is made with the possibility of extraction of the casting during the forward stroke of the movable detachable part 2.

Such a sign will simplify the design, as well as the manufacturing technology and application of the injection mold, since it does not require the use of special mechanical, hydraulic and other devices that serve as autonomous drive units of the sign.

Options for performing a utility model:

- the surface of the piston 4 and the mating surface of the forming cavity 3 are different from the cylindrical shape;

- at the end of the sign from the side of the piston 4 is made at least one recess 6;

- in the detachable fixed part 1, at least one recess 6 is made;

- detachable movable part of the mold is assembled from at least two halves;

- a pusher is passed through the rod and piston;

- the piston is spring loaded;

- the forming cavity is in communication with a source of compressed air;

- the rod is covered by friction elements of the brake mechanism.

The essence of the utility model is illustrated by illustrations, where in FIG. 1 shows a general diagram of a mold for injection molding in its initial position; in FIG. 2 is the same as in FIG. 1, but when melt is injected into it (intermediate position of the piston); in FIG. 3 is the same as in FIG. 2, but when pushing the casting; in FIG. 4 is the same as in FIG. 3, but upon release of the casting from the mold sign; in FIG. 5 and 6 show local views A and B of FIG. 3 to the junction of the casting, respectively, with a sign and with the end of the movable part of the injection mold; in FIG. 7 and 8 are the same as in FIG. 5 and 6, but at the time the casting is torn off, respectively, from the sign and from the mentioned end face; in FIG. 9 and 10 show diagrams of the execution of the movable part of the mold from two halves along section BB in FIG. 3, respectively, in open and closed state; in FIG. 11 shows an embodiment of a mold in which the sign is spring-loaded; in FIG. 12 shows an embodiment of a mold in which its movable part is provided with an air channel; in FIG. 13 shows an embodiment of a mold, which is further provided with casting followers; in FIG. 14 and 15 — an embodiment of a mold in which the sign is braked is shown, respectively, in its free and inhibited state.

Mold for injection molding (Fig. 1), contains a fixed detachable part 1 and a movable detachable part 2, made with the possibility of its direct and reverse, and, located in it forming cavity 3 of variable volume, in which there is a sign in in the form of a piston 4, mating with its surface and provided with at least one rod 5, which may be integral with the piston 4. More than one rod 5, the sign may contain (not shown) in the case, for example, of strengthening its design or in the case of casting under pressure from the center nym hole. For better extraction of the casting from the mold, the surface of the piston 4 and the surface of the forming cavity 3 mating with it are different from the cylindrical shape.

The surface of the piston 4 and the mating surface of the forming cavity 3 may be different from a cylindrical shape. For example, they can be made (not shown) rectilinear or with curved mating surfaces of complex shape.

At the end of the sign on the piston 4 side and in the detachable fixed part 1, at least one hole 6 is made (in Fig. 1-4 one such hole is shown on the sign and two on the detachable fixed part 1). Moreover, the hole 6 in the end of the sign from the side of the piston 4 is made at the end of the rod 5, passed through the piston 4.

Moreover, the sign is made with the possibility of its direct stroke X (in Fig. 2 - in the arrow to the left) under the action of the melt 7 injected under pressure p (in Fig. 2 - in the curved arrow to the right) through the fixed part 1 into the forming cavity 3 of the moving part 2 , and with the possibility of pushing out the casting 8 (Fig. 3, 4) from the forward stroke Y (in Fig. 3 - in the arrow to the left).

For injection of the melt 7 (Fig. 2), the fixed part 7 is provided with a nozzle 9, to which the output part of the injection machine (not shown) is supplied for feeding the melt 7.

The rod 5 is movably located in the guide 10, sandwiched between the insert 11 and the cover 12 of the detachable part 1. The insert 11 therein is enclosed by a housing 13 and provided with a cooling jacket 14 where coolant (not shown) is supplied.

The detachable part 7 is made with the possibility of its movement using the closing-opening unit of the injection machine (only its fixed and movable plates 15 and 16 are shown). Between the end of the sign and the nozzle 9, a feature of the device (not shown) of the movable plate 16, a guaranteed gap Δ (Fig. 1) is formed as an element of the hydraulic resistance "nozzle-damper".

The holes 6 in the end face of the sign on the piston 4 side and in the detachable fixed part 1 are configured to form (Fig. 5, 6) contour lines 17 of complex configuration in the casting 8 due to its protrusions 18 obtained by melt flowing 7 (Fig. 2) into these holes 6, as well as with the possibility of formation (Fig. 7, 8) of the shanks 19 at the ends of the casting 8 after it is removed from the mold.

To improve the extraction of the casting 8 from the mold, it may have the following additional improvements.

The movable part 2 of the mold can be made of two halves 20 (Fig. 9), covering the casting 8 with the possibility of its release (Fig. 10). In this case, a mechanical, hydraulic or pneumatic drive (not shown) can be used to open and close the halves 20 of the movable part 2 of the mold.

The piston 4 of the mold sign can be preloaded by the compression spring 21 relative to the guide 10 of the rod 5 (Fig. 11).

An embodiment of the mold is also possible (FIG. 12), the movable part 2 of which can be provided with an air channel 22 communicating the forming cavity 3 through a hose 23 with a source of compressed air pressure (not shown). As an embodiment of the method, it is possible to communicate (shown by dashed lines) a source of compressed air with a forming cavity 3 behind the piston 4 through an air channel 24 made directly in the piston 4 through a check valve 25 located therein.

It is also possible for the mold to have one or more pushers 26 (Fig. 13), which are passed, as shown, through the guide 10 and piston 4, or (not shown) through the rod 5 and piston 4.

The mold can also be equipped with a braking mechanism, the friction elements 27 (Fig. 14) of which are located near the rod 5, with the possibility of preloading it (Fig. 15) and ensuring the braking of the movement of the piston 4 during injection under pressure through the nozzle 9 of the melt. An option to slow down the movement of the piston 4 can also be a variant with a compression spring 21 placed behind the piston 4 (Fig. 1, which will restrain the piston 4 with its force. Another variant of the mentioned braking can be the location (not shown) of the brake mechanism directly inside the forming cavity 3.

Injection molding is carried out using the above-described mold as follows.

In the initial position (Fig. 1) of the plates 15 and 16 of the injection molding machine, the releasable parts 7 and 2 of the mold are closed and under pressure, and the rod 5 together with the piston 4 are in the extreme right position.

Then (Fig. 2), an injection unit of the injection machine (not shown) is brought to the inlet of the mold, through which the melt 7 is fed through the nozzle 9 under pressure p. Overcoming the hydraulic resistance created by the mutual arrangement with a guaranteed gap Δ of the nozzle 9 and the piston 4, the laminar jet of the melt 7, entering the gap Δ, hits the end face of the piston 4, sharply changing its direction along this end. Therefore, together with the movement of X of the piston 4 with its rod 5 under the pressure of the melt 7, particles of this melt mix (its turbulent motion), which helps to eliminate the negative effects of the “free stream”, “cold junctions” when filling with melt 7, the forming cavity 3 in the boundary flows of melt 7, close to the surface of the forming cavity 3, which are present in the mold of analogue [1] and prototype [2].

In this case, the thermal casting is controlled by the supply of coolant (not shown) to the cooling jacket 14, and, if necessary, around the stationary part 2 (not shown).

Under the influence of the pressure of the melt 7, the rod 5 with the support platform 17 will move to the leftmost position, while the support platform will abut against the limiter (not shown). The piston 4 also occupies the extreme left position, forming the necessary volume of the forming cavity 3, in which the hot melt will be located.

After that, the flow of melt 7 through the nozzle 9 is stopped. The melt 7 cools down, hardening and forming in the forming cavity a specific shape defined by the contour of the forming cavity 3. Due to the previously obtained turbulence effect of the flow of melt 7, which eliminates the above-mentioned negative effects, inside the obtained casting cold junctions are not formed, gas and shrinkage porosities, shells are significantly reduced, and on its surface, as well as on the surface of the forming cavity 3, it is not formed soot.

To extract the molded casting 8 (Fig. 3), a direct stroke Y of the movable detachable part 2. In this case (Fig. 3), the piston 4, remaining in place due to the engagement of the protrusion 18 (Fig. 5) of the casting 8 with the end face of the rod 5, pushes the casting 8, when moving the movable part 2, which is located at a distance from the fixed part 1. At the same time, the casting 8 is located between them, holding its protrusions 18 in the holes 6 (Fig. 5 and 6) of the end of the rod 5 and the end of the fixed part 1.

In the final stage of the forward stroke of the movable detachable part 2 (Fig. 4), the casting 8 (Figs. 4 and 7) is detached from the piston 4 of the sign, due to the fact that the number of protrusions 18 located in the holes 6 is greater in the casting 8 in the place of its conjugation with the fixed part 7 (Fig. 6) than at the place of conjugation of this casting with the end face of the rod 5 (Fig. 5). At the end of the stroke of the movable plate 16 of the injection molding machine when working on the aforementioned opening of the movable part 2 with the fixed part 1, the protrusion 18 leaves the hole 6 at the end of the rod 5, forming a shank 19 in the casting 8 9 of FIG. 7), and the protrusion 18 on the fixed part 1 is still held in its hole 6 (Fig. 8). This can be implemented in several ways:

- holes 6 at the end of the rod 5 and the fixed part 1 are the same in size and shape, but on the fixed part 1 they are larger in number (as shown), respectively, the holding force of the casting 8 there is more;

- holes 6 are the same in number (not shown) in the mentioned places, but at the end of the rod 5, the size of the holes 6 is smaller, therefore, the casting 8 remains on the stationary part 1 of the mold.

- holes at the end of the rod 5 and fewer in number, and they are smaller in size than on the plate (not shown), so the casting 8 also remains on the stationary part 1 of the mold.

As a result, the piston 4 with the rod 5 and the supporting platform 17 occupy their original position with respect to their location in the mold (Fig. 1).

The final removal of the casting 8 from the end of the stationary part 1 (Fig. 4) occurs either by tearing the material out of the holes 6 (Fig. 6) under the action of the applied force, manually or using an automatic device (not shown), or due to the shrinkage of the material of the casting 8, when the size of the protrusion 18 in the holes 6 decreases, and he freely leaves from there with the formation of shanks 19 (Fig. 8) at the end of the casting 8.

After removing the casting 8 from the mold, the detachable parts 7 and 2 are closed under the action of the movable plate 16 of the injection machine, and are under pressure, according to FIG. 1. Next, the mold cycle is repeated.

Another way to remove the casting 8 from the mold is to ensure its free fall under the action of gravity. In this case (Figs. 9 and 10), the movable part 2 is structurally able to disconnect its two halves 20 at the end of the mold opening stroke, and the freed casting 8 freely falls down, for example, into a special technological container. The opening and closing of the halves 20 can be carried out using any known mechanical, hydraulic or pneumatic actuators (not shown).

There is also a way to extract the casting using the piston 4 (Fig. 11), for example, by the force of a compression spring 21 located behind the piston 4. The cycle of the mold with such a spring-loaded piston 4 is similar to that for a mold without it (Fig. 1 -four).

A method is also possible for extracting the casting by supplying compressed air to the forming cavity 3 behind the piston 4 (Fig. 12) through the air channel 22 through the hose 23. As a result, the piston 4 returns to its original position.

As an embodiment of this method, it is possible for compressed air to flow through the air channel 24, made directly in the stem 5, through a check valve 25 located in the piston 4.

In this case, compressed air through the opening check valve 25 will act directly on the casting 8 (Fig. 2), pushing it out of the forming cavity 3.

It is also possible to extract the casting 8 using the pushers 26 (Fig. 13), passed through the piston or through the piston rod and piston. When the movable part 2 of the press-form is opened to the left during the opening (Fig. 3), the pushers 26 (Fig. 13) push the casting 8 under the action of its drive mechanism (not shown).

It is useful to apply during operation of the mold the braking of the stroke of the piston 4 when it moves under the action of the injected melt 7 (Fig. 15). Braking can be achieved, for example, by clamping the piston rod 5 by friction elements 27 of the brake mechanism (not shown) with a force that provides incomplete fixation of the rod 5. This provides better “shedding” of the forming cavity, eliminates the effect of the “free stream”, reduces the formation of pores in casting 8 (Fig. 3).

A variant of the method of braking the piston 4 can also be a variant with a compression spring 21 located behind the piston (Fig. 11), which restrains the piston 5 with its force.

Another option for braking the piston 4 may be braking (not shown) directly of the piston in the cylinder itself.

Information sources:

1. Patent RU 2010667 C1, IPC B22D 17/22, priority from 1990.12.13, published 1994.04.15.

2. Patent RU 94903 U1, IPC B29C 45/00, B29C 45/12, B22D 17/22, priority from 2009.04.22, published 2012.02.20 / prototype /.

Claims (9)

1. A mold for injection molding, containing a fixed detachable part and a movable detachable part, made with the possibility of its direct and reverse motion and with a variable-volume cavity located in it, in which a sign in the form of a piston mating with its surface is located and equipped with at least one rod, and the sign is made with the possibility of its direct course under the action of the melt injected through the fixed part, and with the possibility of extracting the casting formed in the forming cavity p IG Petritskaya portion, characterized in that the token is adapted to extract the direct casting during the moving of the split portion. 2. The mold according to claim 1, characterized in that the surface of the piston and the surface of the forming cavity mating with it are different from the cylindrical shape. 3. The mold according to claim 1, characterized in that at least one recess is made in the end face of the sign on the piston side. 4. The mold according to claim 1, characterized in that at least one recess is made in its detachable fixed part. 5. The mold according to claim 1, characterized in that the detachable movable part of the mold is assembled from at least two halves. 6. The mold according to claim 1, characterized in that a pusher is passed through the rod and piston. 7. The mold according to claim 1, characterized in that the piston is spring-loaded. 8. The mold according to claim 1, characterized in that the forming cavity is in communication with a source of compressed air. 9. The mold according to claim 1, characterized in that the rod is covered by friction elements of the brake mechanism.