INJECTION MOLD AND METHOD FOR MANUFACTURING INJECTION-MOLDED PARTS

Abstract

An injection mold for manufacturing injection-molded parts by injecting injection molding material into a cavity having a contour corresponding to the injection-molded part to be manufactured. The injection mold includes a distribution channel for injection molding material which is connectable to an injection nozzle and is in communicative connection with the cavity. The distribution channel includes a compensating volume region having a volume, determined by the type and number of cavities connected to the distribution channel, for accommodating injection molding material during the injection molding process.

Claims

1. An injection mold for manufacturing injection-molded parts by injecting injection molding material into a cavity having a contour substantially corresponding to the injection-molded part to be manufactured, the injection mold comprising: a distribution channel for injection molding material which is connectable to an injection nozzle and is in communicative connection with the cavity; a compensating volume region provided for the distribution channel, the compensating volume region having a volume determined by a type and number of cavities connected to the distribution channel to accommodate injection molding material during the injection molding process.

2. The injection mold according to claim 1, wherein the compensating volume region has a receiving opening, and wherein a compensation insert is present which is selectively insertable into the receiving opening, the compensation insert having an indentation, which communicates with the distribution channel to provide a compensating volume, and wherein different compensation inserts having different compensating volumes being selectively insertable into the receiving opening.

3. The injection mold according to claim 2, wherein the compensation inserts have an end-face side with an indentation that provides the compensating volume with a radially outwardly leading groove merging into the indentation, and the distribution channel being communicatively connectable to the indentation via the groove when the compensation insert is inserted into the receiving opening of the injection mold.

4. The injection mold according to claim 2, wherein the compensation inserts are cylindrical.

5. The injection mold according to claim 2, wherein a set of compensation inserts is present which at their end-face side have indentations having different diameters.

6. The injection mold according to claim 2, wherein a set of compensation inserts is present which have at least two different outer diameters, the injection mold having receiving openings determined by the cavities and having a diameter that provides a compensating volume that is adapted to the cavities.

7. The injection mold according to claim 1, wherein two or more cavities are connected to a distribution channel, and the distribution channel is in communicative connection with at least one compensating volume, a position of one of the compensating volumes with respect to one of the cavities, and a size of the compensating volume being determined by the combination of the cavities.

8. The injection mold according to claim 1, wherein the compensating volume region, as a branch, is connected to the distribution channel in the region of the transition of the distribution channel into the associated cavity.

9. The injection mold according to claim 1, wherein for at least one cavity connected to the distribution channel, a compensating volume is connected to the distribution channel adjacent to a transition of the distribution channel into a cavity.

10. The injection mold according to claim 1, wherein the injection mold has an injection molding material distribution unit with a nozzle-side mounting frame and an ejection-side mounting frame, the nozzle-side mounting frame and/or the ejection-side mounting frame being designed for accommodating mold inserts having cavities, and the distribution channels with the compensating volume regions being introduced into the mold inserts or into the nozzle-side mounting frame and/or the ejection-side mounting frame.

11. A method for manufacturing injection-molded parts using an injection mold according to claim 1, the method comprising: introducing a compensating volume for forming the injection mold, the compensating volume being in communicative connection with the distribution channel, and providing a volume for accommodating injection molding material that is adapted to the type and number of cavities connected to the distribution channel.

12. The method according to claim 11, further comprising: selecting compensation inserts from a set different compensation inserts that provide various compensation volumes such that a number, position, and size of the compensation volumes are adapted to the type and number of cavities connected to the distribution channel; and inserting the selected compensation inserts into a respective associated receiving opening in the compensating volume region of the injection mold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0037] FIG. 1 shows a diagram of a top view of a mold half of an injection mold;

[0038] FIG. 2 shows a perspective view of a first group of injection-molded parts with compensation material sections;

[0039] FIG. 3 shows a perspective view from FIG. 2 with compensation inserts;

[0040] FIG. 4 shows a perspective view of a second group of injection-molded parts with compensation material sections;

[0041] FIG. 5 shows a perspective view from FIG. 4 with compensation inserts;

[0042] FIG. 6 shows a diagram of a set of compensation inserts;

[0043] FIGS. 7A and 7B show a top view of the first and second group of injection-molded parts with compensation inserts; and

[0044] FIGS. 8A and 8B show a top view of the first and second group of injection-molded parts with compensation material sections.

DETAILED DESCRIPTION

[0045] FIG. 1 shows a perspective view of an injection mold 1 that includes a mounting frame 2 for accommodating a group of mold inserts 3a, 3b. In principle, the number of mold inserts 3a, 3b in a group is not limited to the two mold inserts 3a, 3b illustrated. Rather, any given number of at least two mold inserts 3a, 3b may form a group.

[0046] The injection mold 1 has a distribution channel 4 which, with multiple sections in the illustrated example, is introduced into the separate mold inserts 3a, 3b. The sections of the distribution channel 4 are connected to a shared injection point 5 for an injection molding material injection nozzle.

[0047] The sections forming a shared distribution channel 4 in each case open into at least one cavity 6a, 6b. The cavities 6a, 6b each have a contour and shape in three dimensions which determine the shape of the particular injection-molded part to be manufactured using a cavity 6a, 6b. An injection-molded part is manufactured by injecting injection molding material through the shared injection molding material injection nozzle and the sections of the shared distribution channel 4 branching to the group of cavities 6a, 6b and into the cavities 6a, 6b of the group, which are connected to the branches of the distribution channel 4.

[0048] If the injection volumes for the particular branches from the injection nozzle of the shared injection site 5 into the illustrated various branches of the shared distribution channel 4 are different, uniform filling of the cavities 6a, 6b is no longer reliably ensured. This applies in particular for the case when different injection-molded parts having different volumes are simultaneously supplied via a shared distribution channel 4. It is thus apparent that the upper cavity 6a has a larger surface area, and thus a larger volume, than the lower cavity 6b.

[0049] In order to now balance the injection molding volumes introduced into the various branches of the distribution channel 4, starting from the shared injection point, for each branch of the shared distribution channel 4 going out from the shared injection point 5 the same shot weight, i.e., the same capacity volume of injection molding material, is set by means of compensation volumes 7 that are in communicative connection with the distribution channel 4.

[0050] In order to balance the smaller volume of the lower cavity 6b with the larger volume of the upper cavity 6a, the compensation volumes 7b for this lower mold insert 3b are noticeably larger than the compensation volumes 7a for the upper mold insert 3a.

[0051] In the illustrated example, a balancing weight 7a or 7b is present at each of the two branches of the distribution channel 4 in the respective mold insert 3a, 3b, in each case adjacent to the opening into the associated cavity 6a, 6b. This ensures symmetrical filling of the particular cavity 6a, 6b with inclusion of excess injection molding material near the particular opening site into the cavity 6a, 6b.

[0052] Depending on the size and routing of the individual branches of the shared distribution channel 4 into the associated cavity 6a, 6b, the size of the compensation volumes for a shared cavity 6a, 6b may also be different in order to balance out a different filling behavior at multiple opening sites into a shared cavity 6a, 6b, by means of the compensation volumes 7a, 7b. The intent is thus to achieve approximately the same filling behavior for all opening sites of a cavity 6a, 6b.

[0053] The compensation volumes 7a, 7b as well as the cavities 6a, 6b may be introduced directly into the particular mold 3a, 3b as a compensation cavity. This is meaningful as a simple variant when the make-up of the group of cavities 6a, 6b or optionally a group of different molds 3a, 3b for the different cavities 6a, 6b is known and remains unchanged.

[0054] However, if during operation, different groups of molds 3a, 3b having different types and numbers are combined, each of which is supplied via a shared injection point 5 and which thus forms a shared cooperating channel 4, adapting the size of the compensation volumes 7a, 7b is beneficial. Therefore, the molds 3a, 3b in the illustrated example have receiving openings 9a, 9b that are provided for receiving compensation inserts 8a, 8b.

[0055] The receiving openings 9a, 9b may have the same shape, for example the same diameter, so that a type of compensation insert 8a, 8b having the uniform shape and the uniform diameter may then be inserted into the mold inserts 3a, 3b.

[0056] In the illustrated example, another option is shown in which (two, for example) different receiving openings 9a, 9b having different shapes are provided. In the illustrated example, the receiving openings 9a, 9b are cylindrical. They differ from one another via different diameters. Thus, for example, two types of receiving openings 9a, 9b and correspondingly, two different types of compensation inserts 8a, 8b, which differ from one another via two different diameters may be present in a set. However, it is similarly possible to also provide three, four, or more different types of compensation inserts, if necessary.

[0057] A compensation cavity in the form of a hollow space, whose volume determines the compensating volume 7a, 7b, is then introduced at the end-face side of the compensation inserts 8a, 8b.

[0058] This compensating volume 7a, 7b is then communicatively connected to the adjoining section of the distribution channel 4 by appropriate alignment via a groove 10. As an alternative to the groove 10, the compensation inserts 8a, 8b may also have an opening that is closed all around, via which the compensation volumes 7a, 7b communicate with the adjoining section of the distribution channel 4.

[0059] FIG. 2 shows a perspective view of injection-molded parts 11a, 11b which, by use of the injection mold 1 from FIG. 1, have been manufactured by injecting plastic material as injection molding material. It is apparent that webs 12 lead to the injection-molded parts 11a, 11b, starting from the shared injection site 5. The webs 12 correspond to the shape and the course of the distribution channels 4. The compensation material sections 13a, 13b, corresponding to the shape and size of the compensation volumes 7a, 7b, are present adjacent to the opening into the respective injection-molded part 11a, 11b, i.e., the associated cavity 6a, 6b.

[0060] The volume of the smaller injection-molded part 11a, together with the volume of the webs 12 leading to the shared injection point 5 and the compensating material 13b, corresponds to the volume of the larger injection-molded part 11b together with the webs leading from the shared injection point 5 to this injection-molded part 11b and the compensation materials 13a.

[0061] The volume leading to the two injection-molded parts 11a, 11b of the two-part group, i.e., the shot weight, is balanced in this way. The so-called shot weight for the right portion of the group, viewed from the injection point 5, is approximately equal to the shot weight of the left portion of the group.

[0062] FIG. 3 shows the illustration of the injection-molded parts 11a, 11b from FIG. 2, now together with the respective compensation inserts 8a, 8b. It is apparent that these compensation inserts are cylindrical and have two different diameters. An indentation that is delimited by an edge (collar) and that receives the compensation masses 13a, 13b is present at the end-face side of the cylindrical compensation inserts 8a, 8b. The indentation, by its diameter and its depth, determines the desired compensating volume 7a, 7b, which results in a balanced shot weight for the regions of the group of cavities 6a, 6b and associated injection-molded parts 11a, 11b that are connected to a shared injection point 5.

[0063] For a communicative connection to the adjoining distribution channel 4, the groove 10 must be aligned with the adjoining distribution channel 4 or the web 12 produced by same. This takes place via a suitable alignment contour in the injection mold 1 or the respective mold 3a, 3b, and a corresponding contour at the compensation insert 8a, 8b. In the illustrated example, a radially protruding collar 14 is present at the end opposite from the end face-side compensating volume 7a, 7b, and has a flat area 15 as an encoding and alignment contour. Thus, only with such an alignment can the compensation insert 8a, 8b be inserted into a correspondingly encoded, contoured receiving opening 9a, 9b, which ensures the transition of the groove 10 into the adjoining distribution channel 4.

[0064] This alignment contour 15 may be situated, for example, opposite from the groove 10 as shown in the top view.

[0065] However, other alignment contours, such as protruding tabs, depressions, and the like that deviate from a symmetrical configuration of the compensation insert 8a, 8b are also conceivable.

[0066] It is also conceivable for the compensation inserts 8a, 8b to have an overall asymmetrical contour, such as a rectangular contour, which allows insertion into the receiving opening 9a, 9b in only one or two ways, thus ensuring that the groove 10 is aligned with the distribution channel 4.

[0067] FIG. 4 shows another group of injection-molded parts 11a, 11c. It is clear that the injection-molded part 11a, which in the example had the larger volume, now has a smaller volume than the other injection-molded part 11c. This is the reason that compensation volumes 7a have also been provided with the compensating material 13a at the first injection-molded part 11a. When limited to the above-described first type of group, this would not be necessary as such, provided that the largest cavity 6a of a group determines the shot weight.

[0068] However, this cannot be ensured with a variable combination of different cavities 6a, 6b, 6c to form a group.

[0069] In the example according to FIG. 4, the injection-molded part 11c constitutes the largest part to be manufactured using the injection mold 1, and thus establishes the highest shot weight. For this injection-molded part 11c and the associated cavity 6c, no receiving opening 9a, 9b for insertion of a compensation insert 8a, 8b is then necessary.

[0070] However, in the mold 3a, 3b, for such a cavity 6c a compensation opening 9a, 9b adjoining the distribution channel 4 may still be provided as a precaution. This compensation opening 9a, 9b may then be fitted with a compensation insert 8a, 8b which has a closed end-face side and thus, a compensating volume of zero. For the case that a combination of a group still takes place in which one cavity 6a, 6b is larger, the required compensating volume may still be set.

[0071] In the example, small downwardly protruding tabs 16 at the webs 12 are discernible. These tabs are also present at the other sections of the webs 12, and do not represent a compensating volume 7a, 7b within the meaning of the present invention. Their volume is much too small to result in effective balancing of the shot weight. Rather, such tabs are present, via intentional indentation, for position fixing during cooling and ejection, or result from guide openings for plungers of an ejection tool on the ejection side of the mold.

[0072] FIG. 5 shows the example from FIG. 4 in a perspective view, together with the compensation inserts 8a and the compensation masses 13a accommodated in the end-face end.

[0073] FIG. 6 shows a set of compensation inserts 8a, 8b. The set is made up of two different types of cylindrical compensation inserts 8a, 8b having different diameters.

[0074] Each of these compensation inserts 8a, 8b at its end-face side has a compensation cavity 17 with a different diameter. The depths of the compensation cavities 17 may also be different for the compensation inserts 8a, 8b of a set. Different compensation volumes 7a, 7b are thus provided. By selecting a suitable compensation insert 8a, 8b having the compensating volume 7a, 7b necessary for balancing the shot weight, the mold inserts 3a, 3b for the combination of a group of mold inserts 3a, 3b, and thus a group of cavities 6a, 6b, may be coordinated with one another so that the shot weights of the cavities 6a, 6b, formed by a shared distribution channel 4 at a shared injection site 5, each accommodate the same injection molding volume.

[0075] It is also apparent that the compensation cavities 17 at the end-face sides of the compensation inserts 8a, 8b are delimited by a circumferential edge 18 that is interrupted by a radial outwardly leading groove 10.

[0076] The depth of the groove 10 may be greater than the depth of the compensation cavity 17. The flow behavior may be influenced by the design of the groove 10.

[0077] FIGS. 7A and 7B show a top view of the first group illustrated in FIGS. 1 through 3, and of the second group illustrated in FIGS. 4 and 5, of injection-molded parts 11a, 11b, 11c.

[0078] In a comparison of FIGS. 7A and 7B, it is apparent that for the same injection-molded part 11a in the left group (FIG. 7A), a smaller compensating volume 7a has been selected than for the other make-up of the group in combination with the larger injection-molded part 11c (FIG. 7B).

[0079] Thus, it is not necessary for a single shot weight, i.e., a single injection volume per mold 3a, 3b, to be determining, regardless of the make-up of the group. Rather, an effort is made for the shot weight for the particular combined group, starting from the shared injection point 5, to be the same. As illustrated for the make-up of the group according to FIG. 7B, this may result in a higher shot weight per injection-molded part 11a, 11b and volumes connected thereto, than for the group illustrated in FIG. 7A.

[0080] FIGS. 8A and 8B once again show a top view of the injection-molded parts 11a, 11b, 11c, manufactured after injection of the injection molding material, together with the webs 12 integrally formed thereon and compensation masses 13a, 13a, 13b after removal from the injection mold 1.

[0081] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.