GUIDING AND CENTERING DEVICE

Abstract

The present invention relates to a guiding and centering device (10) for a forming tool (2), in particular an injection molding or die-casting tool, comprising a first mold half (1) and a second mold half (5) which are guided by guide means (7) from a closed position in which the respective separating surfaces of both mold halves (1; 5) are pressed against one another into an opened position and vice versa. This guiding and centering device (10) comprises a protruding guiding body (4) formed as a circular cylindrical bolt (12) provided at the first mold half (1), a guiding recess (6) formed as a bush (14) with an circular cylindrical inner surface (20) provided at the second mold half (5) and a rolling element cage (16) with rolling elements (17) inserted in rows (18), by means of which the two mold halves (1; 5) are guided and precisely centered in the closed position. The rolling element cage (16) is supported by the circular cylindrical inner surface (20) of the bush (14) and positioned via positioning means (30) in such a way that when closing the forming tool the circular cylindrical bolt (12) runs practically simultaneously in a first row of rolling elements (18.1) and a second row of rolling elements (18.2) of the rolling element cage (16).

Claims

1. Guiding and centering device for a forming tool comprising a first mold half and a second mold half which are guided by guide means between a closed position in which respective separating surfaces of both mold halves are pressed against one another, into an opened position and vice versa, the guiding and centering device comprising a protruding guiding body formed as a circular cylindrical bolt provided at the first mold half, a guiding recess formed as a bush with a first circular cylindrical inner surface provided at the second mold half, and a rolling element cage with rolling elements inserted in rows, by means of which the first and second mold halves are guided and precisely centered in the closed position, wherein the rolling element cage is supported by the first circular cylindrical inner surface of the bush and positioned via positioning means in such a way that when closing the forming tool the circular cylindrical bolt runs substantially simultaneously in a first row of rolling elements and a second row of rolling elements of the rolling element cage.

2. Guiding and centering device for a forming tool according to claim 1, wherein the positioning means are formed from a spring element and an axial retainer element arranged such that the rolling element cage is axially positioned in the bush between them.

3. Guiding and centering device for a forming tool according to claim 1, wherein a groove is provided at an end portion of the first circular cylindrical inner surface of the bush, in which a circlip is insertable to axially position the positioning means.

4. Guiding and centering device for a forming tool according to claim 1, wherein a shoulder is formed at an end portion of the first circular cylindrical inner surface of the bush which forms a support of the positioning means.

5. Guiding and centering device for a forming tool according to claim 1, wherein connecting the bush to the second mold half is via a locking member, which is insertable into one of a series of circumferential grooves surrounding the bush and formed along an axial length of the bush and which protrudes into a recess formed at the second mold half.

6. Guiding and centering device for a forming tool according to claim 1, wherein connecting the circular cylindrical bolt to the first mold half is via a locking member, which is insertable into a series of circumferential grooves surrounding the bolt and formed along an axial length of the bolt and which protrudes into a recess formed at the first mold half.

7. Guiding and centering device for a forming tool according to claim 5, wherein the locking member is formed from a circlip.

8. Guiding and centering device for a forming tool according to claim 6, wherein the locking member is formed from a circlip.

9. Guiding and centering device for a forming tool according to claim 5, wherein the locking member is formed from two ring parts with a circumferential slot, which are connected to each other via a seal ring insertable into the slot.

10. Guiding and centering device for a forming tool according to claim 6, wherein the locking member is formed from two ring parts with a circumferential slot, which are connected to each other via a seal ring insertable into the slot.

11. Guiding and centering device for a forming tool according to claim 1, wherein the bush and/or the circular cylindrical bolt are configured with a lead-in geometry.

12. Guiding and centering device for a forming tool according to claim 1, wherein the circular cylindrical bolt has a conical retraction region adjacent to an edge, which concludes a circular circumferential surface of the bolt.

13. Guiding and centering device for a forming tool according to claim 1, wherein the first circular cylindrical inner surface of the bush is concluded by an edge adjacent to which a second circular cylindrical inner surface is formed, the second circular inner surface having a greater diameter than the first circular cylindrical inner surface.

14. Guiding and centering device for a forming tool according to claim 11, wherein the edge transits from the first circular cylindrical inner surface to the second circular cylindrical inner surface with a curvature, which is adapted to a curvature of the rolling elements.

15. Guiding and centering device for a forming tool according to claim 1, wherein the rolling elements are rollers or balls.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] For a more complete understanding of the invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures, in which like reference characters designate like parts and in which:

[0035] FIG. 1 is a schematically guiding and centering device according to prior art;

[0036] FIG. 2 is a schematically guiding and centering device according to an embodiment of the invention;

[0037] FIG. 3 is a schematically guiding and centering device in section according to the embodiment of the invention;

[0038] FIG. 4a is a schematically guiding and centering device partly in section according to the embodiment of the invention showing the movement of the guide body into the guide recess when the forming tool is closing;

[0039] FIG. 4b is a schematically guiding and centering device partly in section according to the embodiment of the invention shown in FIG. 4a in another position when closing the forming tool;

[0040] FIG. 5 is a schematically locking element of an embodiment of the invention for positioning the guiding and centering device relative to the forming tool.

DETAILED DESCRIPTION

[0041] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the invention and together with the description serve to explain the principles of the invention.

[0042] Referring to FIG. 1 shows a known mold configuration with a centering device and guide means. In a first mold half 1 of a forming tool 2 protruding guide bodies 4, which have the shape of cuboids are fastened in the region of the separating surface 3. Other forms of the protruding guide bodies are known such as conical or cylindrical. Furthermore, guide means 7 formed from known guide columns are positioned to guide the forming tool 2 during movement. Not shown in FIG. 1. on a second half mode 5 of the forming tool 2, guide recesses 6 are provided which have the shape of slots and which correspond to the guide bodies 4 of the first mold half 1. In the closed state of the molding tool 2, the guide bodies 4 are located in the guide recesses 6 enabling optimal alignment of the first mold half 1 with the second mold half 5. Due to the design of the guide bodies 4 and the guide recesses 6, these must be used at least in pairs and twice to order to be able to center in all directions. Therefore, the guide bodies 4 and the guide recesses 6 have to be arranged essentially opposite one another, which can result in space problems. In this known centering device, the surface pressure acting on the guide body and the guide recess can be very high. Furthermore, the corresponding guide surfaces must be moved against each other in a sliding manner, resulting in high wear, which in turns means that these centering devices have to be replaced after a certain time.

[0043] Referring to FIG. 2 and FIG. 3 showing a guiding and centering device 10 according to the invention in a possible arrangement in the forming tool 2. According to this embodiment, each protruding guide body 4 is formed from a circular cylindrical bolt 12, in particular the guide columns of the guide means 7. Each guide recess 6 is formed from a bush 14 with a circular cylindrical inner surface 20 supporting a rolling element cage 16 with rolling elements 17 inserted in rows 18. The circular cylindrical bolt 12 runs in the rolling elements 17 of the rolling element cage 16 when the forming tool 2 is closed. FIG. 2 shows a view of the first mold half 1 of the forming tool 2, in particular the molding tool, comprising guide means 7 designed as guide columns known in prior art and formed from the circular cylindrical bolt 12 according to the invention. Therefore, in the embodiment shown, four such bolts 12 are inserted into the first mold half 1 as in general the forming tool 2 comprises four guiding sets. Principally, for obtaining an optimal centering two bolts 12 are required, but any number of bolts 12 can be used in the forming tool 2, depending on the size and configuration of the forming tool 2.

[0044] FIG. 3 shows a view of the forming tool 2 with the first mold half 1 with an arranged circular cylindrical bolt 12 as the guide body 4, in particular the guide columns of the guide means 7 and of the second mold half 5 with an arranged bush 14 in which a rolling element cage 16 is inserted in an open position.

[0045] The guide recess 6, which is configured as the bush 14 with a circular cylindrical inner surface 20, is fastened in the second mold half 5 of the forming tool 2, as will be described later. The rolling element cage 16 is inserted into the bush 14 supported by the circular cylindrical inner surface 20. The rolling element cage 16 comprises rolling elements 17 arranged in rows 18, wherein the rolling elements 17 can be configured as rollers or balls.

[0046] For positioning the rolling element cage 16 positioning means 30 are provided. According to one embodiment shown in FIG. 3 positioning means 30 comprise a retainer element 32 formed from a circlip 34 or a snap ring positioned near an opening of the bush 14 toward the circular cylindrical bolt 12, wherein the circlip 34 is inserted into a groove provided in the circular cylindrical inner surface 20. Furthermore, the positioning means 30 comprise a spring element 31 configured to bias the rolling element cage 16 from an opposite end therefrom toward the retainer element 32. An end of the spring element 31 facing away from the rolling element cage 16 is supported by a stop element, which can be formed from another circlip 34 inserted into a groove provided at the circular cylindrical inner surface 20 at an end portion opposite the opening for inserting the bolt 12 or by a shoulder protruding inwardly from the circular cylindrical inner surface 20. The spring element 31 formed from a compression spring presses the rolling element cage 16 against the retainer element 32, which means that the rolling element cage 16 is in the correct position when the forming tool 2 is open. The correct position of the rolling element cage 16 is such that when closing the forming tool 2 the circular cylindrical bolt 12 runs practically simultaneously on the first row of the rolling elements 17 and the second row of rolling elements 17 at the same time, whereby the load on the rolling elements 17 and them supporting surfaces can be divided, which results in increased service life, shown in detail in FIGS. 4a, 4b.

[0047] Advantageously, the bush 14 is provided with an entrance portion with a lead-in geometry comprising an edge 21 concluding the circular cylindrical inner surface 20 and providing a transition into a second circular cylindrical inner surface 22. As a result, the point at which the full preload force is reached on the rolling elements 17 is precisely defined, with the rolling elements 17 being driven gently through the conical retraction area 22. The circular cylindrical bolt 12 is configured with a lead-in geometry at a head of the bolt 12, such that the bolt 12 can be easily inserted into the rolling element cage 16, as described later.

[0048] A further advantageous embodiment of the invention is that the bush 14 can be positioned relative to the second mold half 5 and the bolt 12 can be positioned relative to the first mold half 1 by means of a locking member 40 providing individual position and variability of the dimensions, in particular thickness of the plates of the forming tool 2. The locking member 40 is formed as a ring or ring parts 44 which are insertable into a circumferential groove 41. Therefore, a series of circumferential grooves 41 surrounding the bush 14 and/or the bolt 12 and formed along an axial length thereof is formed. The ring or ring parts 44 inserted into one of the circumferential grooves 41 protrudes into a recess 42 of the plates of the forming tool 2. The recess 42 can be formed from a shoulder between plates.

[0049] As can be seen from FIG. 3 the guide body 4 can be fastened to the first mold half 1 in a similar way via locking member 40 inserted into a circumferential groove 41 formed at an outer surface of the guide body 4 and protruding into a recess 42 formed in the first mold half 1 or between plates forming the first mold half 1.

[0050] FIGS. 4a and 4b show in section and enlarged details of the guiding and centering device 10 when the forming tool 2 is closing. Thereby, the circular cylindrical bolt 12 runs into the rolling element cage 16 positioned in the bush 14 via positioning means 30 formed as the spring element 31 (not shown) and the retainer element 32. The bush 14 has the circular cylindrical inner surface 20 which is concluded by an edge 21. Adjoining to the edge 21 a transition region is configured such to transit from the edge 21 into a second circular cylindrical inner surface 22 which has a greater diameter than the circular cylindrical inner surface 20. The transition region between the inner surfaces 20; 22 can be formed with a rounding or curvature which is preferably adapted to the rounding of the rolling elements 17. Furthermore, the circular cylindrical bolt 12 has a circular circumferential surface 52, which is concluded by an edge 51. Adjoining to the edge 51 the head of the bolt 12 is formed from a conical retraction area 50, which provides the lead-in geometry.

[0051] When the forming mold 2 is closing the circular cylindrical bolt 12 runs into the rolling element cage 16 with the lead-in geometry formed from the conical retraction area 50. As can be seen from FIG. 4a the bolt 12 passes over a first row 18.1 of rolling elements 17 arranged in the rolling element cage 16, since the rolling elements 17 of the first row 18.1 are located in the area of the second circular cylindrical inner surface 22, in particular in the region of the edge 21 and therefore in a relation to the bush 14 in a retracted position. As the circular cylindrical bolt 12 advances further, the edge 51 of the bolt 12 comes into contact with the second row 18.2 of the rolling elements 17 arranged in the rolling element cage 16. As soon as the edge 51 of the bolt 12 passes over the rollers 17 of the first row 18.1, these rolling elements 17 begin to rotate, the rolling element cage 16 is pushed into the bush 14 and sets the rolling elements 17 of the second row 18.2 in motion, as can be seen from FIG. 4b. With this arrangement, the rolling elements 17 of the first row 18.1 and of the second row 18.2 come under pretension practically at the same time, whereby the load can be divided.

[0052] During the further closing process of the forming tool 2, the circular cylindrical bolt 12 passes over the rolling elements 17 of further rows 18, which are arranged in the rolling element cage 16. In the complete closed position of the forming mold 2, the circular cylindrical bolt 12 is pushed into the rolling element cage 16 and thus the centering forces are transmitted from the rolling elements 17 of the rolling element cage 16. By opening the forming tool 2, the bolt 12 is retracted out of the bush 14 and the rolling element cage 16 is positioned accordingly such that the next centering process can be performed in an optimal manner.

[0053] In FIG. 5 the locking member 40 is shown in a perspective view. The locking member 40 is formed from two halves of a ring 44. The ring 44 provides a circumferential slot 45 configured that a seal ring 46 can be inserted to hold the halves of the ring together. With this arrangement it is easy to position the bush 14 in a predetermined position in the second mold half 5 and the bolt 12 in the first mold half 1. Therefore, the guiding and centering device 10 can be adapted to different dimensions of the plates of the forming mold 2 providing a universal applicable guiding and centering device with optimal centering and guiding properties.