WO2009133130A1

WO2009133130A1 - Casting device for producing hollow cast objects with non-rotationally symmetrical projectile

Info

Publication number: WO2009133130A1
Application number: PCT/EP2009/055178
Authority: WO
Inventors: Devid Mosca
Original assignee: Röchling Automotive AG & Co. KG
Priority date: 2008-04-30
Filing date: 2009-04-29
Publication date: 2009-11-05
Also published as: JP2011518698A; DE102008021592B3; DE102008021592C5; JP5361992B2

Abstract

A casting device for producing hollow cast objects comprises a cavity, a filling device for filling flowable casting material into the cavity, a displacement device designed to drive a projectile (10) into, preferably through, the casting material filled into the cavity, wherein the projectile extends along a projectile longitudinal axis (12), and wherein the projectile (10) has a non-rotationally symmetrical cross-section in at least one axial contour section (48) of the longitudinal extension thereof.

Description

Casting device for producing hollow cast articles with non-rotationally symmetrical projectile

description

5

The present invention relates to a casting apparatus for producing hollow cast articles, comprising a cavity, a filling device for filling flowable casting material into the cavity, a displacement device which is designed to project, preferably through, a projectile for movement into the casting material filled in the cavity therethrough, with the projectile extending along a projectile longitudinal axis.

Such a device is known, for example, from EP 0 757 936 A. Such a casting apparatus, disclosed in the cited document as an injection molding apparatus, is used to first fill a cavity with flowable casting material and subsequently displace casting material filled into the cavity partially through the projectile, which is driven for movement by the casting material. 2o The motion drive takes place through a fluid ejection nozzle, which directs fluid under pressure to a projectile provided and this drives it.

During the passage of the projectile through the casting material filled into the cavity, the projectile generally produces a cavity whose cross-section approximates a projection of the projectile in projectile longitudinal axis.

In the above-mentioned document is given as an example of a projectile, a 30 ball.

Although good results can be achieved with spheres if hollow cast articles having a substantially circular inner contour are desired, however, it is precisely in the field of manufacturing hollow molded sealing articles, such as elastomer sealing tubes, that there is a need for contoured shapes of the inner surface of the cavity of the casting to deviate from a circular cross-section.

It is therefore an object of the present invention, a casting device of the type mentioned in such a way that with her hollow castings with a greater variety of inner surface shapes can be produced, as is the case in the prior art.

This object is achieved by a generic casting device, wherein the projectile has a non-rotationally symmetrical cross section at least in an axial contour section of its longitudinal extent. This cross-section is to be considered in a cross-sectional plane orthogonal to the projectile longitudinal axis.

Since only rotationally symmetrical projectiles have hitherto been used in the prior art because of their positional stability when passing through the cavity, the possibility of using an at least partially non-rotationally symmetrical projectile offered by the inventors of the present application offers a significant expansion of producible inner surface shapes of the inner casting molds produced by the casting device according to the invention hollow cast objects.

Since, as mentioned above, only the projection of the projectile in projectile longitudinal axis with respect to the inner shape of the hollow casting object determines the shape, it is sufficient according to the invention that only one axial longitudinal section of the projectile has a non-rotationally symmetrical cross section. However, it should not be excluded that the projectile has a non-rotationally symmetrical cross-section over its substantially entire axial length. Incidentally, in this application, if it is mentioned that the filling device is designed to fill flowable casting material into the cavity, this should also include only a partial filling of the cavity with casting material, since the casting material should not be excluded a filled part of the cavity is displaced by the projectile and its movement into the initially unfilled portion of the cavity.

The axial longitudinal section of the projectile, which has a non-rotationally symmetrical cross section, is referred to in the present application as a "contour section".

In order to ensure that the contour section acts on the casting material filled in the cavity during the passage of the projectile, the contour section is preferably arranged and configured such that a virtual enveloping cylinder surrounding the projectile radially outwardly with the projectile longitudinal axis as the cylinder axis forms the projectile touched in the region of its contour section.

The term "envelope cylinder" here refers to a merely imaginary cylinder whose cylinder axis coincides with the projectile longitudinal axis and whose diameter is chosen such that it touches the point of the projectile which is located farthest away from the projectile longitudinal axis as a tilting cylinder.

One particularly frequently desired contouring of the inner surface of the produced hollow cast article is a groove extending longitudinally of the cast article which can be advantageously produced by having the projectile having a projectile core with a projectile jacket, the projectile jacket extending at least one from the projectile longitudinal axis Having radially away extending radial projection.

Should additionally or alternatively be thought of, the inner surface of the hollow cast article to be produced with a in the longitudinal direction Forming a projecting projection, this can be achieved with the aforementioned projectile in that its projectile jacket has at least one radial recess extending radially toward the projectile longitudinal axis.

The term "projectile core" refers to a radially outwardly projecting outer surface of the projectile, with a portion of the outer surface facing radially outward when its normal vector is one the projectile longitudinal axis has radially outwardly facing component.

For a reduction of the flow resistance of the projectile when penetrating into the casting material and thus for reducing the energy required to drive the projectile, it is advantageous if the radial height of the radial projection and / or the radial depth of the radial recess, based on the projectile core without radial projection or / and radial recess, at least partially changes in the axial direction.

It is particularly advantageous if the radial height of the radial projection at least partially increases in the axial direction from the leading end of the projectile to its trailing end, wherein particularly preferably the radial height of the radial projection increases in the axial direction continuously and without steps.

During its movement through the casting material filled into the cavity, the projectile may rotate about its projectile longitudinal axis. Nevertheless, satisfactory results can be achieved with the projectile described above if a defined contoured inner shape of the hollow cast article to be produced is required only in the region of its end region near the projectile stop position. This may be the case if the internal contouring, for example on a pipe, the connection with a pipe in the following longitudinal axis Object is used, which penetrates only along a certain depth of penetration of said longitudinal end ago in the generated hollow cast article.

However, the above-mentioned undesirable turning of the projectile around its longitudinal axis as it passes through the cavity can also be reduced or even prevented along the entire projectile trajectory in that at least one radial projection serves as a stabilizer rib, which passes through the cavity when passing the projectile their associated guide recess interacts.

The guide recess guides the projectile by means of the stabilizer rib, which protrudes radially into the guide recess. It is particularly advantageous if a recess already present in the cavity for shaping the casting object can be used as a guide recess.

Since casting material filled into the cavity generally first begins to solidify on the walls of the cavity, a solidified layer of casting material also forms on the guide recess, covering the wall regions of the guide recess, so that movement of the stabilizer rib as it passes through the cavity in the Essentially in the circumferential direction around the projectile trajectory is positively limited by the guide recess or the layers of solidified thereon casting material without undesirably high flow resistance. The guide recess, optionally in conjunction with the hardened Gießmaterialschichten adjacent thereto, thus forms a rotation of the projectile against rotation about its longitudinal axis, namely substantially over the entire projectile trajectory.

A particularly stable and secure guidance can be obtained according to an advantageous development of the present invention, characterized in that the stabilizer rib substantially over the entire axial length of the projectile.

A particularly wide variety of different possible designs of the projectile-generated inner surface of the hollow cast article can be obtained by having at least one radial projection, viewing a cross-section in a cross-sectional plane orthogonal to the projectile longitudinal axis, at least in an axial section of the projectile and at least in a radial section of the radial projection has a radially varying width. The width is to be measured in the circumferential direction around the projectile longitudinal axis. Such depending on the radial position widths of the radial projection are of particular interest in the region of its radially outer end, since they form the base of the groove produced by the respective radial projection. If it is desired to reduce the flow resistance of the projectile when passing through the casting material, then the radial projection can advantageously be designed such that it tapers towards its radially outer end.

According to preferred constructional embodiments, the radial projection, when viewing a cross-section in a cross-sectional plane orthogonally to the projectile longitudinal axis, at least in an axial portion of the projectile and at least in the region of its radially outer end have a triangular, trapezoidal or rectangular shape, preferably with rounded corners.

The positional stability of the projectile during its movement through the casting material filled into the cavity can be further improved in that the transitions from the projectile core to the radial projection are rounded in the circumferential direction. Sharp-edged transitions from the projectile core to the radial projection can cause unwanted turbulence or flow separation, which could cause the projectile to spin.

A particularly high precision of a radial projection in the higher formed groove casting can be achieved in that the radial projection over as large an axial length as possible in contact with the casting material. In order to provide the longest possible contact length of the radial projection with small projectile mass, it can be provided that at least one radial projection projects beyond the projectile core at its trailing longitudinal end in the axial direction. This applies in particular to the radial projection forming a stabilizer rib, since a higher guide fidelity is associated here with its increasing length. Particularly preferably, the radially outer end of the respective radial projection projects beyond the projectile core in the axial direction to a greater extent than radially inwardly located sections of the radial projection, since the radially outer end is usually designed with a small width in the circumferential direction about the projectile longitudinal axis and thus, despite its length, does not generate excessively high flow resistance.

The shape of an inner surface of a hollow cast article to be formed may be chosen in almost any manner when the projectile comprises a plurality of radial protrusions and / or radial recesses. Of course, it can basically be envisaged that the majority of radial projections and / or radial recesses are arranged equidistantly in the circumferential direction around the projectile longitudinal axis. However, due to the greater constructional freedom in the configuration of the inner surface of the hollow cast article, it is particularly preferred that the radial projections and / or radial depressions are arranged in the circumferential direction at different distances from each other.

The variety in the design of the inner surface of the hollow cast article to be produced can be further enhanced by the projectile comprising a plurality of radial projections and / or radial recesses, of which at least two radial projections and / or radial recesses, when viewed in cross-section and the same to the projectile longitudinal axis orthogonal cross-sectional plane different radial dimensions and / or different widths in the circumferential direction around the Projectile longitudinal axis and / or have a different width change in the radial direction.

In principle, the present casting device should be operable with any casting materials. However, the casting device described above is preferably an injection molding device which processes thermoplastic as casting material.

The above object of the present invention is also achieved by a projectile for an injection molding process with projectile injection technology, which is designed according to at least one of the above-mentioned aspects. Since such a projectile is an independently tradable good, the Applicant seeks independent patent protection for the building on the same inventive idea projectile.

It should be added that, to reduce its flow resistance, the projectile advantageously tapers along its projectile longitudinal axis to its leading longitudinal end.

The present invention will be explained in more detail with reference to the accompanying drawings. It shows:

1 is a perspective view of a projectile of a casting device according to the invention obliquely from behind,

FIG. 2 is a side view of the projectile of FIG. 1; FIG.

Fig. 3 is a rear view of the projectile of Figures 1 and 2 and

4 shows a cross-section of a hollow cast object produced by means of a casting device according to the invention and the projectile of FIGS. 1 to 3. In FIGS. 1 to 3, a projectile for use in a casting device according to the invention is designated generally by 10. The projectile 10 extends along a projectile longitudinal axis 12 with a projecting in projectile direction B longitudinal end 14 and a trailing longitudinal end 16th

The projectile has a projectile core 18 which is substantially rotationally symmetrical in the example of FIGS. 1 to 3 and has a projectile jacket 20. The projectile core 18 is the part of the projectile 10 located radially inside the lines 22, 24 and 26.

The projectile jacket 20 has a first region 20a, which also includes the leading longitudinal end 14 of the projectile 10, in which the projectile 10, in particular the projectile core 18, tapers in the direction of the projectile longitudinal axis 12 to the leading longitudinal end 14 of the projectile 10. Furthermore, the projectile jacket 20 has a second section 20b in which at least the projectile core 18 has a substantially cylindrical outer shell or, more generally, an outer shell whose cross section does not change along the same axis orthogonal to the projectile longitudinal axis 12. The boundary between regions 20a and 20b is shown by dashed line 28.

Across the circumference of the projectile 10, three radial projections on the projectile core 18 are formed radially outward. Of these, two essentially identical radial projections 30 and 32 lie diametrically opposite one another relative to the projectile longitudinal axis 12. A third radial projection 34 which extends farther radially outward than the first two radial projections 30 and 32 is located circumferentially about the projectile longitudinal axis 12 closer to the radial projection 32 than the radial projection 30th

All the radial projections 30, 32 and 34, like the projectile 10 itself, have a first region 30a, 32a and 34a in which their radial height he related to the projectile core 18 along the projectile longitudinal axis 12 from the leading longitudinal end 14 away to the trailing longitudinal end 16 of the projectile 10 gradually and continuously increased.

Likewise, each radial projection 30, 32 and 34 on the first portion 30 a, 32 a and 34 a in the direction of the projectile longitudinal axis 12 adjacent second portion 30 b, 32 b and 34 b, respectively, in which the cross section of the respective radial projection 30, 32 and 34 does not change when viewed in a direction of the projectile longitudinal axis 12 orthogonal cross-sectional plane along the projectile longitudinal axis 12.

The boundaries between the first region and the second region of the radial projections 30, 32 and 34 are marked with dashed lines around the projectile longitudinal axis 12 partially, for the radial projection 30 with a dashed line 36, for the radial projection 32 with a dashed line Line 38 and for the radial projection 34 with a dashed line 40th

The radial projections 30 and 32 are formed substantially triangular in cross-section and are limited at least in the region of its radially outer end by substantially flat surfaces. In order to reduce the flow resistance of the projectile and to stabilize its position during its movement through flowable casting material, a concave curve 42 or 44 is respectively formed at the foot of the radial projections 30 and 32 located at the projectile core 18, with which a substantially smooth, smooth transition is provided by the projecting in the circumferential direction of the projectile 10 projectile core 18 to the substantially flat boundary surfaces of the radial projections 30 and 32. The peripheral region of the curves 42 and 44 is characterized by dashed lines in its circumferential extent.

As can be seen in the illustrations of FIGS. 1 and 3, the radial projection 34 is delimited by a curved outer surface, which projects completely clings to the Projektivem 18 and thus forms a smooth transition. The peripheral region in which the radial projection 34 extends on the projectile core 18 is indicated by a dashed line 46.

As can be seen in Figure 2, the radial projection 34 extends almost the entire axial length of the projectile 10, so that the contour portion 48 extends over almost the entire axial length of the projectile.

The radial projection 34 with its significantly larger radial extent compared to the radial projections 30 and 32 serves in the example shown in Figures 1 to 3 as a stabilizer rib, which in the movement of the projectile 10 through a cavity of a casting mold with a radial projection 34 associated guide recess the cavity interacts to prevent or at least reduce rotation of the projectile 10 about its projectile longitudinal axis 12 as it moves through the cavity.

The substantially identically constructed radial projections 30 and 32 are formed axially shorter, although they extend to the trailing

Longitudinal end 16 of the projectile, but start only at a greater distance to the leading longitudinal end 14 than the radial projection 34th

In Figure 3, an enveloping cylinder 50 is indicated, the cylinder longitudinal axis 52 coincides with the projectile longitudinal axis 12 and which contacts the projectile 10 at its in the radial direction of the projectile longitudinal axis 12 furthest point 54 as a tilting cylinder.

It should be noted that in FIG. 1, areas 56, 58, 60 and 62 can be seen in the region of the trailing longitudinal section 16 of the projectile 10, which serve to receive the projectile on a fluid ejection nozzle.

FIG. 4 shows the non-hatched cross-section of a cross-section with a cross-section according to the invention. mäßen injection molding device produced tube shown with contoured inner shape. The component is designated 64.

On the inner surface 66 of the component 64 generated by the projectile 10, two grooves with a triangular cross section can be seen, which were generated by the radial projections 30 and 32, respectively. More specifically, the groove 68 is associated with the radial projection 32 and the groove 70 with the radial projection 30th

A located between the grooves 68 and 70 deeper groove 72 has been formed by the radial projection 34, wherein a projection 74 of the component 64 forming mold cavity of the component 64 as a whole forming cavity as a guide recess with the radial projection 34 for inhibiting a rotational movement of the projectile 10 to its projectile longitudinal axis 12 has cooperated.

Here, in the cavity, in particular in the regions 76 and 78 on the mold walls of the projection 74 forming guide recess zones of solidified casting material have formed, which have led the radial projection 34 during the movement of the projectile 10 through the cavity.

Claims

claims

A casting apparatus for producing hollow cast articles, comprising: - a cavity,

a filling device for filling flowable casting material into the cavity,

a displacement device, which is designed to drive a projectile (10) for movement into the casting material filled into the cavity, preferably through it, whereby the projectile extends along a projectile longitudinal axis (12), characterized in that the projectile (10) has a non-rotationally symmetrical cross-section at least in an axial contour section (48) of its longitudinal extension.

2. Casting apparatus according to claim 1, characterized in that the non-rotationally symmetrical contour portion (48) is arranged and configured such that a virtual, the projectile (10) radially outwardly surrounding enveloping cylinder (50) with the projectile longitudinal axis (12) Cylinder axis (52) touches the projectile (10) in the region of its contour portion (48).

3. Casting apparatus according to claim 1 or 2, characterized in that the projectile (10) has a projectile core (18) with a projectile jacket (20), wherein the projectile jacket

(20) at least one radial projection (30, 32, 34) extending radially away from the projectile longitudinal axis (12) and / or at least one radial recess extending radially toward the projectile longitudinal axis (12).

4. Casting device according to claim 3, characterized in that the radial height of the radial projection (30, 32, 34) and / or the radial depth of the radial recess, based on the same projectile jacket (20) without radial projection (30, 32, 34) and / or radial recess, at least partially changes in the axial direction.

5 5. Casting apparatus according to claim 4, characterized in that the radial height of the radial projection (30, 32, 34) increases in the axial direction from the leading end (14) of the projectile to the trailing end (16) out at least in sections.

10

6. Casting device according to one of claims 3 to 5, characterized in that at least one radial projection (34) serves as a stabilizer rib, which interacts with the passage of the projectile (10) through the cavity with an associated guide recess i5.

7. Casting device according to claim 6, characterized in that the stabilizer rib (34) extends substantially over the entire axial length of the projectile (10).

20

8. Casting device according to one of claims 3 to 7, characterized in that at least one radial projection (30, 32, 34), when viewing a cross section in a cross-sectional plane orthogonal to the projectile longitudinal axis (12), at least in an axial section 25 of the Projectile (10) and at least in a radial section of the

Radial projection (30, 32, 34), preferably in the region of its radially outer end, a radially varying width in the circumferential direction around the projectile longitudinal axis (12), preferably tapers towards its radially outer end.

30

9. Casting device according to one of claims 3 to 8, characterized in that a radial projection (30, 32), when viewed in cross-section in a cross-sectional plane orthogonal to Projectile longitudinal axis (12), at least in an axial portion of the projectile (10) and at least in the region of its radially outer end has a triangular, trapezoidal or rectangular shape, preferably with rounded corners.

5

10. Casting device according to one of claims 3 to 9, characterized in that the transitions from the projectile core (18) to the radial projection (30, 32, 34) are rounded in the circumferential direction.

10

11. Casting device according to one of claims 3 to 10, in particular with the inclusion of claim 6, characterized in that at least one radial projection (30, 32, 34), in particular a stabilizer rib forming Radialvor- jump (34), preferably the radially outer End of the radial projection, the projectile core (18) projects beyond the trailing longitudinal end in the axial direction.

12. Casting device according to one of claims 3 to 11,

20 characterized in that the projectile (10) has a plurality of

Radial projections (30, 32, 34) and / or radial recesses comprises, which are arranged in particular in the circumferential direction at different distances from each other.

13. Casting device according to one of claims 3 to 12, characterized in that the projectile (10) comprises a plurality of radial projections (30, 32, 34) and / or radial recesses, of which at least two radial projections (30, 32, 34) or / and radial depressions, when considering a cross section in one and

30 same to the projectile longitudinal axis (12) orthogonal cross-sectional plane have different radial dimensions and / or different widths in the circumferential direction about the projectile longitudinal axis (12) and / or a different width change in the radial direction.

14. Casting device according to one of the preceding claims, characterized in that it is an injection molding with thermoplastic material as the casting material.

15. projectile (10) for an injection molding process with projectile injection technology with the features of claim 1 and optionally with further features of one of claims 2 to 13.