KR20080041642A - Injection-moulding device with needle valve nozzle and guide bush - Google Patents

Abstract

Injection-moulding device (1) with a feed plate (3), in which at least one flow channel (4) for a flowable material is formed, with at least one needle valve nozzle, through which the flowable material can be fed in continuation of the flow channel to a separable mould insert, with at least one shut-off needle (20), at least a portion of which passes through the flow channel in a longitudinally displaceable manner and which can be brought by means of a drive into an open position and a closed position, and with a guide bush (30) for leading the shut-off needle (20) through and sealing it. The guide bush has a region which encloses the shut-off needle with a small amount of play and at least a portion of which lies in the flow channel. The region thereby has a contact surface for the flowable material, at least a portion of which lies in the flow channel. The region and the contact surface (44) are flowed around by flowable material on all sides.

Description

Injection-Moulding Device with Needle Valve Nozzle and Guide Bush}

The present invention relates to an injection molding apparatus having a needle valve nozzle according to the preamble of claim 1.

A needle valve nozzle is used in the injection molding apparatus to guide the flowable material to the detachable molding cartridge under high pressure at a preset temperature. The injection molding apparatus has a closing nozzle which is mainly operated pneumatically or hydraulically, the closing nozzle periodically opening and closing the sprue in the molding cartridge. This allows for accurate material metering, in particular for rapid continuous filling. However, the flowable material may also be injected in a segmented manner, for example in cascade casting.

Each blocking needle is axially displaceably supported in the tool side region of the injection molding apparatus and preferably through the flow channel for the material to be treated in the nozzle side region (for example DE 32 49 486 C3 or See DE 34 03 603 A1). The flow channel ends in a nozzle orifice that forms a nozzle outlet opening on the end side. In the blocking position the lower end of the blocking needle is inserted into a sealing sheet formed in the nozzle orifice or in the forming cartridge.

For sealing guidance of the blocking needle, a guide bush or sealing sleeve is usually used in the distribution plate of the injection molding apparatus, which receives the cylindrical leg of the blocking needle (for example DE 39 26 357). A1 or EP 1 223 020 B1). Between the blocking needle and the bush is maintained a cylindrical free space through which the flowable material is permeated during operation of the injection molding apparatus, whereby the needle is sealed against the flow channel. At the same time a lubricating effect is formed, which reduces the friction between the blocking needle and the bush.

Despite this optimal sealing system structure, due to the relatively high pressure in the tool and the reciprocating motion of the needle, it is not possible to prevent the material to be treated from passing through the guide bush or the sealing bush to the outside. The result is material loss. The residual material thereby contaminates the tool as well as the blocking needle, which not only impairs the sealing effect. It can continually interfere with the opening and closing movement of the blocking needle. Expensive cleaning or maintenance work is inevitable.

It is an object of the present invention to avoid the above and other disadvantages of the prior art and to further improve the guidance and sealing of the blocking needle in the injection molding apparatus. It is particularly aimed at a sealing device which can be formed inexpensively by simple means and can be easily handled.

The main features of the invention are set forth in claim 1. Embodiments are the subject matter of claims 2 to 23.

The present invention provides an injection molding apparatus having a distribution plate, at least one needle valve nozzle, at least one blocking needle, and a guide bush for penetrating and sealing the blocking needle, wherein the distribution plate has at least a portion of a fluid for the flow. One flow channel is formed, and the flow channel is continued by the needle valve nozzle, and the flow material can be supplied to the detachable molding cartridge, and the blocking needle penetrates the flow channel at least stepwise in a longitudinal direction to displace the driving unit. The guide bush comprises at least one region, which region comprises blocking needles with a slight movement clearance and is located at least stepwise in the flow channel.

The region of the guide bush is thereby always in direct contact with the flowing material which pressurizes the guide bush in each injection process. In this way, the contact area is pressed tightly against the blocking needle while overcoming the slight movement play, so that during the high pressure step the material can no longer reach the outside from the injection molding apparatus through the guide bush. At the same time, the blocking needle is fixed in the center position by the guide bush, so that the deflection movement of the needle during the injection pressure step cannot be shown. As the injection pressure decreases, the needle is freed again by the guide bush and can be immediately placed in the closed position.

In addition to the above advantages, the region has or forms at least one contact surface for the flow material, which is likewise located at least stepwise in the flow channel. Thus the material to be treated can directly affect the contact surface and the guide bush can act like a check valve in this region.

The area having the contact surface has a structural advantage when protruding in the flow channel in the radial or axial direction. This not only simplifies the structure of the guide bush, but also simplifies its assembly, which benefits the manufacturing cost and the assembly cost as a whole.

It is particularly preferred when a flowing material flows on all sides in the region and / or the contact surface. The flow material may simultaneously affect the guide bush or the contact surface such that the protruding areas within the flow area are compressed evenly over the entire periphery of the blocking needle. The needle is sealed on all sides and centered in the central position. The region also includes a cylindrical inner circumference oriented coaxially with respect to the blocking needle. The inner circumference forms a centering element for the needle as well as the sealing surface between the needle and the guide bush.

The cylindrical inner circumference and the contact surface are substantially at the same height in the axial direction, ie the cylindrical inner circumference is likewise directly located in the flow channel so that pressure can act directly on the sealing surface or the centering element.

A preferred refinement provides that a region projecting into the flow channel forms an end region of the guide bush and the contact surface is formed by the outer periphery of the region. It can also be made as simple as the inexpensive structure of the guide bush, which can preferably be produced as a rotating member.

In order to ensure uniform pressing of the guide bush, the outer periphery of the end region is preferably an inclined plane, preferably a conical plane. This does not only improve contact with the flowing material. At the same time, the wall thickness of the end region, which can always be reliably pressed radially, also decreases. In this case the conical surface may be desirable when formed concave or convex.

According to another aspect of the invention, the guide bush having an axial gap with respect to the protruding region in the flow channel comprises at least one further region comprising a cylindrical inner circumference oriented coaxially with respect to the blocking needle, and preferably The stacked end regions receive blocking needles with as little movement play as possible. This ensures that the blocking needle is always correctly held and guided at the midpoint so that deflection from the central position is effectively prevented at least in the guide bush.

The free space formed between the end regions, the inner diameter of which is slightly larger than the outer diameter of the blocking needle, is lubricated of the guided blocking needle in the guide bush through the material to be treated which reduces the friction in the guide bush.

The end region and the free space preferably form a central through bore.

According to another important embodiment of the invention, the guide bush is arranged in the distribution plate. However, the guide bush may alternatively or additionally be arranged in the needle valve nozzle. In this case, the guide bush is preferably located in the recess in the distribution plate and / or the needle valve nozzle, and the guide bush is fixable in the recess.

The guide bush is thus sealed perpendicularly to the longitudinal axis through at least one surface inside the recess, in order to prevent material from passing through the recess and exiting the tool, the surface preferably forming the bottom of the recess. .

For the manipulation and manufacture of the guide bush, it is preferred when the guide bush comprises a flange located centrally in the recess. A neck section is formed in the flange that supports or forms a protruding region in the flow channel at the end side.

If the wall thickness of the end region is chosen to be less than the wall thickness of the neck section as a whole, the end region is compressed particularly uniformly in the radial direction during each injection process. The inner circumference of the end region is positioned around the outer circumference of the blocking needle in a formally coupled manner, such as, for example, a valve, so that no more material can penetrate from the flow channel into the bush 30 and thus cannot reach the outside.

The flange and neck section are preferably integral. However, they may be constructed separately and made of different materials.

Other features, details, and advantages of the invention are provided from the description of the embodiments with reference to the claims and the following figures.

1 is a schematic partial cross-sectional view of an injection molding apparatus with a sealing device for a blocking needle.

2 is another cross-sectional view of the sealing device of FIG.

The injection molding apparatus, commonly designated by reference number 1 in FIG. 1, is used for the production of molded articles from flowable materials, such as plastic melts. The injection molding apparatus comprises a stationary plate 2 and a distribution plate 3 parallel thereto, in which a flow channel 4 system is formed. The flow channel 4 joins into each needle valve nozzle (not shown), which is assembled to the lower surface 5 of the distribution plate 3.

Each needle valve nozzle preferably comprises an externally heated nozzle (not shown), in which material conduits to the extension of the flow channel 4 are formed concentric about the longitudinal axis L. do. The flow channel terminates in a nozzle orifice integrally formed with the nozzle outlet opening, wherein the material to be treated is supplied by the nozzle outlet opening to a moldable cartridge (not shown) which is separable through the spout.

A blocking needle 20 is preferably provided for opening and closing of the spout formed in the molding cartridge, which blocks the flow channel in the needle valve nozzle and the section of the flow channel 4 in the distribution plate 3 in the longitudinal direction. It is movably penetrated to move from the mechanical, electrical, pneumatic or hydraulic drive (not shown) to the closed and open positions. A blocking needle 20 having a blocking component (not shown) formed at the end side is sealedly inserted into the spout through the nozzle discharge opening in the closed position.

In the tool side region the blocking needle 20 is connected with the drive through the distribution plate 3 and the fixing plate 2, the needle 20 being provided with an end side adapter 22 provided with an angular end section 23 in cross section. Support. The adapter 22 is used for setting up the tool (not shown) so that the needle 20 can be assembled and the length can be adjusted. A needle nut (not shown) may be used to secure the needle 20 in a rotatable manner.

A through bore 6 is inserted into the fixing plate 2 for the penetration of the needle 20, the inner diameter of the through bore being larger than the outer diameter of the blocking needle 20.

In addition, a cleaning device 10 for the blocking needle is formed in the fixed plate 2. The cleaning device 10 comprises a housing 11 having a substantially cylindrical wall and a flange edge 13 protruding radially inwardly on the end side. The flange edge 13 axially supports a plurality of disc shaped cleaning elements 40, which are maintained at a uniform spacing by the annular spacer 14 on the edge side. In order to secure the cleaning element 40 formed as a flat body and the spacer 14 positioned therebetween in the cleaning apparatus 10, a fixing ring 15 which is preferably axially screwed to the housing 11. This is used.

Each cleaning element 40 is provided at its center with an opening (not shown) for the penetration of the blocking needle 20. In this case the inner diameter of the opening is chosen such that the edge formed by the opening is in formally and frictionally engaging contact with the outer periphery 24 of the blocking needle 20. Residual material condensed on the outer periphery 24 of the blocking needle 20 and transmitted, for example, from the guide bush 30, is always reliably detected by the edge adapted to the shape of the cleaning element 40 and thus from the needle 20. It is removed, ie the blocking needle 20 penetrating through the cleaning device 10 or the cleaning element 40 remains clean during the operation of the injection molding device 1 in each reciprocating motion.

Located in the distribution plate 3 is a guide bush 30 with a central through bore 31 as a needle seal, the inner diameter of the through bore being at the end regions 32 and 33 of the bush 30. It corresponds to the outer diameter of the blocking needle 20 without slight movement play. Thus, the blocking needle has a center guide and a support inside the bush 30.

An axial cylindrical free space 34 is formed between the end region or the guide region 32, 33, the inner diameter of which is slightly larger than the outer diameter of the blocking needle 20. The free space intentionally receives a small amount of flow material from the flow channel 4 during the operation of the injection molding apparatus, which causes the sealing needle 20 to be sealed about the flow channel 4 and the tool periphery. At the same time, the flowable material acts as an antifriction agent in the free space 34, thereby reducing the friction between the blocking needle 20 and the guide bush 30. The guide bush is located coaxially with respect to the longitudinal needle L of the blocking needle 20 or the blocking needle-likewise through the guide bore 6 in the stationary plate 2.

The guide bush 30 comprises an extended flange 35 centered in the recess 36 in the distribution plate 3. Through the flange 35 the bush 30 comprises a small main part 38 in the outer diameter (in the direction of the fixing plate 2), which main part forms a guide area 32 (top) towards the end side. . The guide region surrounds the blocking needle 20 with a cylindrical inner circumference 42 without slight movement play. At the same time the region limits the cylindrical free space 34 at the top so that the material present therein cannot reach the outside.

The main part 38 is coaxially surrounded by the screw bush 37. The screw bush has an outer thread 47 that engages a corresponding inner thread 56 of the recess 36. When the screw bush 37 is rotationally inserted into the recess 36 and the distribution plate 3, the bush 30 is fixed in the tool. The bottom 41 of the recess 36 and the bottom face of the flange 35 (not shown in more detail) are positioned in form of each other so that the guide bush 30 is not only fixed in the distribution plate 3, At the same time, perpendicular to the longitudinal axis L through a predetermined surface.

The bush 30 includes a neck section 39 (in the direction of the needle valve nozzle) below the flange 35, the outer diameter of which is likewise smaller than the outer diameter of the flange 35. The lower end of the neck section 39 forms a (lower) guide region 33 which surrounds the blocking needle 20 without slight movement play by the cylindrical inner circumference 43 and the cylindrical free space 34. Restricts to the bottom correspondingly. In this case-as shown in more detail in FIG. 2-the wall thickness W of the end region or guide region 33 is preferably formed smaller than the wall thickness U of the neck section 39. The outer circumference 44 of the region 33 also forms an inclined surface 44, preferably a conical surface at the height of the inner circumference 43, so that the wall thickness W is further reduced with respect to the needle valve nozzle.

In order to receive the neck section 39 in the distribution plate 3, a through bore 46 is inserted between the recess 36 and the flow channel 4, the inner diameter of the through bore being substantially in the neck section 39. Matches the outer diameter of). The neck section reaches the flow channel 4, and the end region 33 is radially and concentric with respect to the longitudinal axis L using an inner periphery 43 and a conical surface 44 surrounding the blocking needle 20. Protrude into the flow channel 4. Thus, the guide area 33 for the blocking needle 20 is completely located in the flowable material, and the inclined or conical surface 44 forms a contact surface for the material, which is likewise the blocking needle 20. The material to be treated in the flow channel 4 is generally flowed.

The manner of functioning of the needle seal or guide bush 30 is in effect based on the elastically deformable wall of the end region 33 located in the flow channel 4. When the blocking needle 20 is opened, it first slides undisturbed from the closed position to the open position inside the guide bush 30, and the end regions 32, 33 are circumferentially peripheral to the needle 20 by slight movement play. Slide at 24. When the needle reaches the end position or the open position, an injection pressure is formed, that is, the melt to be processed is pressed by means of high pressure through the melt channel 4 into the molding nest. In this case, the flowable material simultaneously flows the contact surface 44 of the blocking needle 20 and the end region 33 from all sides, and the end region 33 is pressed radially due to the relatively small wall thickness. The cylindrical inner circumference 43 is positioned formally and sealed to the outer circumference 24 of the blocking needle 20, such as a closing element or a valve element, so that the material is guided from the flow channel 4 during the spraying process. It is no longer possible to penetrate into the free space 34 of 30. Since the material at the high pressure loading point in the flow channel 4 can no longer pass through the guide bush 30 and out of the tool, the seal of the blocking needle 20 is reliably improved over the conventional structure. At the same time the needle 20 is fixed in its position concentrically with respect to the longitudinal axis L. The needle can no longer be deflected from its central position through the flow material, which advantageously affects the flow characteristics in the flow channel 4.

At the end of the injection cycle, the pressure in the flow channel 4 again decreases. The end region 33 is again in its original shape due to its elasticity and the inner circumference 43 of the end region is separated from the outer circumference 24 of the blocking needle 20. The blocking needle can be moved undisturbed to the blocking position.

The wall thickness W of the end region 33, preferably made of steel material, is deformable within the elastic region of the material and the slight movement play between the blocking needle 20 and the inner circumference 43 is achieved through the material pressure. By being selected to overcome, the needle 20 in the tool is fixed in the center during the high pressure step so that the material cannot reach the outside. Also between each pressure cycle the needle 20 is accurately guided in the end regions 32, 33 arranged spaced apart from each other.

The present invention is not limited to the above described embodiments but may be applied in various ways. For example, the guide bush 30 does not necessarily need to be arranged in the distribution plate 3. Rather, the guide bush can be assembled in the needle valve nozzle, for example in the nozzle body 5 assembled to the lower surface of the distribution plate 3. To this end the distribution plate has a simple through bore for frictionless penetration of the blocking needle 20 with respect to the drive, while the nozzle body is recessed for receiving the guide bush 30 and the screw bush 37 at the end side. 36) is provided. The neck section 39 of the bush 30 projects axially into the material conduit, while the flow channel 4 directly joins the material conduit on the side below it. Thereby the end region 33, preferably narrowed with respect to the neck section 39 in the outer circumference, is located in the flow region in the axial direction. The contact surface 44 of the flow zone is likewise flowed from all sides by the material to be treated-like the blocking needle 20, so that the pressure present in the flow channel 4 acts as a kind of check valve. ) Can be pressed against the outer periphery 24 of the blocking needle 20 by elastically pressing. The flow channel 4 is thereby completely sealed outward during the spraying process. At this time, the needle 20 is fixed at the central position.

The wall thickness W of the end region or guide region 33 need not necessarily be less than the wall thickness U of the neck section 39. The two regions may comprise almost the wall thickness of the neck section. However, it is important that the end region 33 through which the flow material flows can be elastically deformed during the high pressure phase, so that the inner circumference 43 is located sealed around the outer circumference 24 of the blocking needle 20. It is only.

In some cases, the contact surface 44 formed at the end of the end region 33 can be concave or convex, which can likewise be produced simply and accurately. The progress of the surface advantageously affects the pressure gradient.

For the manufacture of the guide bush 30 in the tool 1, instead of the screw bush 37, a flange ring (not shown) which is screwed with a nozzle to the distribution plate 3 or the needle valve may be used. It is important here that the guide bush 30 must be sealed perpendicularly to the longitudinal axis L via at least one surface 41 inside the recess 36.

The flange 35, the main portion 38 and the neck section 39 are preferably integral. However, the main part 38 and / or the neck section 39 can be formed separately, for example, connected to the flange 35 using a screw connection. This may make the neck section 39 into the end region 33 and the rest of the guide bush 30 from a different material. Alternatively, the neck section 39 can be replaced for a new element whenever necessary without the need for the entire guide bush 30 to be replaced in the treatment by the grinding element.

All of the features and advantages presented from the claims, the specification and the drawings may be important to the invention in different combinations as well as by themselves, including structural details, spatial arrangements and method steps.

<Explanation of symbols for the main parts of the drawings>

L: longitudinal axis 36: recess

U: wall thickness 37: screw bush

W: wall thickness 38: main part

1: injection molding apparatus 39: neck section

2: fixed plate 40: cleaning element

3: distribution plate 41: bottom

4: flow channel 42: inner peripheral

5: bottom surface 43: inner circumference

6: through bore 44: contact surface / peripheral / inclined surface

10: cleaning device 46: through bore

11: housing 47: outer wall

14: spaced apart member 56: inner wall

15: fixed ring

20: blocking needle

22: adapter

23: end section

24: Outer Cast

30; Guide bush

31: through bore

32: end area / guide area

33: end area / guide area

34: free space

35: flange

Claims (23)

Injection molding apparatus 1 having a distribution plate 3, at least one needle valve nozzle, at least one blocking needle 20, and a guide bush 30 for penetrating and sealing the blocking needle 20. At least one flow channel 4 for the flow material is formed in the distribution plate, and the needle valve nozzle allows the flow material to be supplied to the detachable molding cartridge while the flow channel 4 continues. In the injection molding apparatus, the blocking needle can be provided in the open and closed positions by the drive unit at least stepwise displaceably penetrating the flow channel (4), The guide bush (30) comprises at least one area (33) which comprises a blocking needle (20) having a slight movement play and which is located at least stepwise in the flow channel (4). 2. Injection molding apparatus according to claim 1, characterized in that the region (33) has or forms at least one contact surface (44) for the flow material located in the flow channel (4) at least stepwise. The injection molding apparatus according to claim 1 or 2, characterized in that the region (33) projects into the flow channel (4) in the radial or axial direction. 4. Injection molding apparatus according to any one of the preceding claims, characterized in that the region (33) comprises a cylindrical inner circumference (43) oriented coaxially with respect to the blocking needle (20). 5. Injection molding apparatus according to claim 4, characterized in that the cylindrical inner circumference (43) and the contact surface (44) are substantially at the same height in the axial direction. 6. Injection molding apparatus according to any one of the preceding claims, characterized in that the region (33) forms an end region of the guide bush (30). The injection molding apparatus according to any one of claims 1 to 6, wherein the contact surface (44) is formed by the outer periphery of the region (33). Injection molding apparatus according to claim 7, characterized in that the outer periphery (44) is an inclined surface, preferably a conical surface. 9. Injection molding apparatus according to claim 8, characterized in that the conical surface (44) is concave or convex. 10. The guide bush 30 according to claim 1, comprising at least one other region 32 axially spaced relative to the region 33 protruding into the flow channel 4. And the region comprises a cylindrical inner circumference (42) oriented coaxially with respect to the blocking needle (20). 12. Injection molding apparatus according to claim 10, characterized in that the end region (32, 33) receives a blocking needle (20) with as little movement play as possible. 12. The free space 34 is formed between the end regions 32, 33, wherein the inner diameter of the free space is slightly larger than the outer diameter of the blocking needle 20. Injection molding machine. The injection molding apparatus according to claim 10, wherein the end region (32, 33) and the free space (34) form a central through bore (31). 14. Injection molding apparatus according to any one of the preceding claims, characterized in that the guide bush (30) is arranged in the distribution plate (3). The injection molding apparatus according to any one of claims 1 to 13, wherein the guide bush (30) is disposed in the needle valve nozzle. 16. The injection molding apparatus according to any one of the preceding claims, wherein the guide bush (30) is in the recess (36) at the distribution plate (33) and / or needle valve nozzle. The injection molding apparatus according to claim 16, wherein the guide bush (30) is fixable in the recess (36). 18. Injection molding apparatus according to claim 16 or 17, characterized in that the guide bush (30) is sealed perpendicularly to the longitudinal axis (L) via at least one surface (41) inside the recess (36). . 20. The injection molding apparatus according to claim 18, wherein the surface (41) is the bottom of the recess (36). 20. The injection molding apparatus according to any one of claims 16 to 19, wherein the guide bush (30) comprises a flange (35) centered in the recess (36). 21. The injection molding apparatus according to any one of claims 16 to 20, wherein the guide bush (30) comprises a neck section (39) which supports or forms an area (33) at the end side. The injection molding apparatus according to claim 21, wherein the wall thickness (W) of the end region (33) is smaller than the wall thickness (U) of the neck section (39). 23. The injection molding apparatus according to claim 21 or 22, wherein the flange (35) and the neck section (39) are integral.

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