WO1998056562A1

WO1998056562A1 - Molding apparatus

Info

Publication number: WO1998056562A1
Application number: PCT/US1998/012377
Authority: WO
Original assignee: Pleasant, Ronald, E.
Priority date: 1997-06-13
Filing date: 1998-06-11
Publication date: 1998-12-17

Abstract

A removable mold insert (300) for use in injection molding or the like comprises a one piece body stepped along its length to form three sections, namely a locking section (302), a liquid channel section (304), and a base section (306). Each of the sections is in the form of a generally rectangular parallelpiped. Plural outwardly open liquid conduit grooves (318) are provided around the periphery of the liquid channel section.

Description

MOLDING APPARATUS

BACKGROUND

1. Field of Invention

This invention relates to a molding apparatus, such as an injection molding machine, and particularly to mold inserts for machines using readily replaceable injection-side cavity inserts and ejection-side core inserts. However, this invention may also be used for other types of molding such as die casting.

2. Incorporation by Reference

The disclosures of U.S. Patent No. 4,828,479, granted May 9, 1989, to Ronald E. Pleasant, U.S. patent application serial no. 08/387,250, filed February 13, 1995, of Ronald E. Pleasant, U.S. patent application serial no. 08/716,506, filed September 18, 1996, of Ronald E. Pleasant and H. Eugene Lafferty, and PCT application WO 94/09961, published May 11, 1994, are hereby incorporated by reference herein. 2. Prior Art and Other Considerations

The aforementioned U.S. Patent No. 4,828,479 discloses a molding apparatus which uses molds formed by readily replaceable injection-side cavity inserts and ejection-side core inserts. The inserts comprise one- piece cylindrical bodies that are received in correspondingly-shaped holes in rectangular or square mold plates forming the injection side and the ejection side of a master frame. Mold inserts configured as illustrated and described in the 4,828,479 patent have performed satisfactorily, but the cylindrical configuration of the mold inserts presents a problem when molding large parts and/or parts that require additional working area for side actions, stripper bolts, or other mold making features.

The mold inserts to which the 4,828,479 patent relate are used in matched pairs, one being mounted in an

A plate of an injection molding machine and the other mounted on its confronting B plate, and it is critical that the respective mold inserts be precisely aligned with one another during molding. For cylindrical mold inserts as described in the 4,828,479 patent, proper registration of the inserts in their respective A and B plates is maintained by flats on the periphery of the mold inserts and cooperating keys in the A and B plates. However, as the diameter of cylindrical inserts is increased to accommodate larger parts and/or parts that require other mold making features, there is an increased likelihood that the mold inserts may undesirably rotate or clock slightly during use despite the provision of flats and keys.

Also, mold inserts such as those described in the 4,828,479 patent have a liquid channel section with a single liquid conduit groove extending circumferentially therearound. A liquid, such as water or oil, is circulated around the mold insert in the liquid conduit groove for cooling or heating portions of the mold insert. A liquid barrier dam is located in the groove so that the groove is double-ended, one end constituting a liquid inlet end and the other end constituting a liquid outlet end. A master frame with which an insert is used has inlet and outlet connectors aligned with the respective inlet and outlet ends of the liquid conduit groove so that liquid can be introduced into the liquid conduit groove. While a single liquid conduit groove provides satisfactory heating or cooling for most molding needs, it has been discovered that the provision of at least two separate liquid conduit grooves can provide better heating and cooling properties as well as other advantages .

SUMMARY

Therefore, in one aspect, an object of this invention is to provide an improved mold insert that is useful in molding large parts or parts that require other mold making features that necessitate a relatively large mold insert and in which proper registration or orientation of the mold insert in its A plate or B plate can be readily maintained. A related object is to provide a mold insert that is useful in molding large parts without requiring the size of the mold insert to be unduly large. In accordance with this aspect of the invention, a mold insert comprises a generally rectangular, one-piece body stepped along its length to have three sections, namely a first, largest locking section, a second, intermediate liquid channel section, and a third, base section. The rectangular shape of the mold insert permits the use of molding cavities in the mold insert body that are larger in one dimension than another without requiring the body to be unnecessarily large in any one dimension. In addition, the rectangular shape of the mold insert body permits proper registration of the mold insert in its A plate or B plate to be maintained without the use of a key and regardless of the size of the mold insert.

Also, in another aspect, an object of this invention is to provide a mold insert having plural liquid conduit grooves extending circumferentially around the periphery thereof. A mold insert in accordance with this second aspect of this invention, comprises a solid, one-piece metal body stepped along its length to have three sections, namely a first, largest locking section, a second, intermediate liquid channel section, and a third, base section. The liquid channel section has two or more outwardly-open, mutually-parallel, liquid conduit grooves extending around the periphery thereof for receiving a liquid to cool or heat the mold insert. The mold insert can be rectangular or cylindrical, as described above, or any other suitable shape. However, multiple liquid conduit grooves are particularly useful with larger mold inserts, such as the rectangular mold inserts described above.

The multiple liquid conduit grooves permit better heating and cooling of the mold insert by providing multiple circuits or pathways for the liquid. As a result, liquid can travel around the mold insert in different directions, and certain parts of the mold insert can be cooled while other parts are heated, and vice versa. In addition, the provision of two liquid conduit grooves permits the use of bubbler tubes for cooling core sections of a mold insert. Each of the liquid conduit grooves may be configured with undercut side walls to permit the use of liquid barrier dams and/or baffles as described in commonly-owned PCT application WO 94/09961, published May 11, 1994, commonly-owned U.S. patent application serial no. 08/387,250, filed February 13, 1995, and commonly-owned U.S. patent application serial no. 08/716,506, filed September 18, 1996.

Other objects and advantages will become apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 through 3 illustrate a prior art molding apparatus described in the aforementioned patent 4,828,479.

FIG. 4 is a plan view of a portion of a master frame in accordance with this invention showing a mold insert mounted in a mold plate.

FIG. 5 is a plan view of the mold insert shown in FIG. 4. FIG. 6 is a side elevational view of the mold insert of FIG. 5 showing the longer side of the mold insert.

FIG. 7 is a side elevational view of the mold insert of FIG. 5 showing the shorter side of the mold insert.

FIG. 8 is a second embodiment of a mold insert in accordance with this invention.

FIG. 9 is a side elevational view of the mold insert of FIG. 8. FIG. 10 is a side elevational view of a lifter/retainer in accordance with this invention.

FIG. 11 is another side elevational view of the lifter/retainer of FIG. 10 but looking to the right in FIG. 10. FIG. 12 is top plan view of the lifter/retainer .

FIG. 13 is bottom plan view of the lifter/retainer .

FIG. 14 is a fragmentary cross-sectional view showing, in accordance with this invention, a portion of a mold insert secured in a mold plate by a lifter/retainer.

DETAILED DESCRIPTION OF THE DRAWINGS FIGS. 1 through 3 illustrate a prior art master frame 10 described in the aforementioned 4,828,479 patent. For convenience, the reference numbers used in the 4,828,479 patent are used in FIGS. 1 through 3 to identify like parts. Generally, the master frame 10 comprises a first, injection side, generally designated

12, and a second, ejection side, generally designated 14. The injection side 12 includes a first mold plate or A plate 18 having a bore or hole 28 for receiving a generally cylindrical cavity insert 26 therein. The ejection side 14 includes a second mold plate or B plate 144 having a bore or hole 155 for receiving a generally cylindrical core insert 154. The core insert 155 and the cavity insert 26 may be substantially identical except for differences in the core insert 155 required to accommodate an ejector mechanism, the provision of a sprue opening in the cavity insert, and, of course, differences resulting from the configuration of the molded cavity.

FIGS. 5 through 7 illustrate a first embodiment of a mold insert, generally designated 300, in accordance with this invention, which may be either a cavity insert or a core insert. The mold insert 300 comprises a solid, one piece metal body which is stepped along its length to comprise three sections each generally in the shape of a rectangular parallelpiped, namely a first, largest-sized locking section 302, a second, intermediate-sized liquid channel section 304, and a third, smallest-sized base section 306. Each of the sections 302, 304, and 306 has four linear side margins 308 joined by arcuate corner margins 310 to form the general shape of a right parallelogram or rectangle. The insert 300 has a face 312, and the locking section 302 extends from the insert face 312 to a shoulder 314 parallel to the face 312. For reasons which will be described, the locking section 302 is provided with arcuate notches 316 at spaced locations around the periphery thereof, with the notches 316 extending downwardly from the face 312 and opening to the side margins 308 of the locking section 302.

The liquid channel section 304 of the mold insert 300 is provided with two mutually-parallel, outwardly open liquid conduit grooves 318 around the periphery thereof, each of which may be configured substantially as shown and described in the aforementioned PCT publication WO 94/09961 and application serial no. 08/387,250. In particular, each of the grooves 318 extends 360 degrees around the periphery of the liquid channel section 304 and has opposed side walls 320 provided with undercuts 322. The undercuts 322 are provided for use in retaining a liquid barrier dam (not shown) , as described in the WO 94/09961 publication and the 08/387,250 application or in the 08/716,506 application, to make the grooves 318 double- ended. In addition, the undercuts 322 may also be used to retain baffles (not shown) , as described in the

08/716,506 application. As with the inserts 26 described in the 4,828,479 patent, a pair of peripheral grooves 324 is provided on opposite sides of the liquid channel section 302 for receiving O-ring sealing members 326 (FIG. 14) . No O-ring sealing member is provided between the liquid conduit grooves 318 because machine tolerances typically provide a sufficient liquid seal during use, but such an O-ring sealing member could be provided if desired. Although two liquid conduit grooves 318 are illustrated, more than two grooves 318 may be provided if the size of the mold insert 300 permits. In addition, plural liquid conduit grooves 318 may also be provided in cylindrically-configured mold inserts, such as those shown in the 4,828,479 patent.

FIGS. 8 and 9 illustrate a second embodiment of a mold insert, generally designated 330, in accordance with this invention. The mold insert 330 may be substantially identical to the mold insert 300 except that the mold insert 330 is provided with only a single liquid conduit groove 318 in the liquid channel section 304 thereof. Accordingly, like parts are given like reference numbers, and the mold insert 330 is not described further herein. With reference now to FIG. 4, a mold insert 300

(or 330) in accordance with this invention is shown mounted in a mold plate 340 of a master frame 342. The mold plate 340 and the master frame 342 may be configured as described in the 4,828,479 patent but for modifications required to accommodate the generally rectangular configuration of the mold insert 300 (or 330) and the liquid conduit grooves 318 thereof, if more than one is provided. For example, a generally rectangular insert-receiving bore or hole (not shown) must be provided in the mold plate 302 instead of the cylindrical bores or holes 28 and 155 shown in FIGS. 1 through 3. In addition, for the mold insert 300, two liquid inlet connectors 344 and two liquid outlet connectors 346 would be provided in the mold plate 340 - one for each of the liquid conduit grooves 318.

FIG. 4 as well as FIGS. 10 through 14 also illustrate a lifter/retainer, generally designated 350, in accordance with this invention for use in securing and removing a mold insert 300 from the mold plate 340. The lifter/retainer 350 functions in generally the same manner as the retaining and lifting assemblies 70 described in the 4,828,479 patent but has a different construction as will be described below.

With reference particularly to FIGS. 10 through 13, the lifter/retainer 350 comprises a generally cylindrical one-piece metal body 352 having a slot 354 at the lower end thereof cut in from the outer margin of the body 352 along a diameter thereof. A larger slot 356 is key cut above the slot 354. The slots 354 and 356 permit a socket-headed machine screw 358 (FIGS. 4 and 14) to be inserted into and retained centrally within the body 352, with the head 360 of the screw 358 being rotatably trapped in the slot 356 and the shank 362 of the screw 358 extending through the slot 354. A central bore 364 smaller in diameter than the head 360 of the screw 358 is drilled from the top of the body 352 to provide access to the screw head 360.

As shown in FIG. 10, the lifter/retainer body 352 has near the top end thereof a slot 366 extending part way around the circumference thereof which defines an arcuately-extending clamping tongue 368. The same end of the body 352 is provided with a flat 370 terminating in an upwardly-facing shoulder 372 coplanar with the base of the slot 366. The shoulder 372 is spaced circumferentially from the slot 366 by substantially ninety degrees. A notch 374 is provided in the top of the lifter/retainer body 352 to permit the body 352 to be rotated relative the screw 358 as described in the 4,828,479 patent with regard to the retainer and lifter assembly 70 illustrated therein.

Referring to FIG. 14, each of the plural lifter/retainers 350 is mounted to the mold plate 340 in generally the same manner and functions in generally the same manner as the retainer and lifter assembly 70 of the 4,828,479 patent. Each lifter/retainer 350 is received within an arcuate bore or socket 380 open at one side thereof to the insert-receiving bore (not shown) of the mold plate 340, and the screw 358 is threaded into a tapped bore 382 at the base of the socket 380. To place a mold insert 300 into the mold plate 340, each of the lifter/retainers 350 is rotated within its socket 380 to align the flat 370 thereof with the margin of the insert- receiving bore (not shown) in the mold plate 340, which permits the insert 300 to be placed in the bore. When the insert 300 is located in the mold plate 340, each of the lifter/retainers 350 is generally aligned with one of the notches 316 in the locking section 302 of the insert 300, as shown in FIG. 4. Each of the lifter/retainer bodies 352 is then rotated by ninety degrees about its screw 358, as by a screwdriver (not shown) inserted into the notch 374 in the top of the body 352, to move the tongue 368 into the notch 316 aligned therewith. Thereafter, the screw 358 of each lifter/retainer 350 is then tightened using an alien wrench or the like to draw the mold insert 300 snugly into the mold plate 340 and to lock the mold insert 300 in place. To remove the mold insert 300 from the mold plate 340, the steps recited in the preceding paragraph are performed in reverse. The screw 358 of each lifter/retainer 350 is loosened, and the lifter/retainer bodies 352 are reversely rotated by ninety degrees, which moves the tongues 368 out of their corresponding notches 316 and moves the shoulders 372 of the bodies 352 into confronting relationship with the downwardly-facing shoulder 314 of the mold insert 300. The screws 358 can then be rotated to draw the lifter/retainer bodies 358 outwardly of their sockets 380. As a result, the shoulders 372 act against the shoulder 314 of the mold insert 300 to draw the mold insert 300 out of the insert- receiving bore (not shown) in the mold plate 340.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a molding apparatus comprising (a) an injection side having a main injection side frame with an

A plate having at least one exposed face and a cavity insert-receiving hole extending through said A plate opening to its said exposed face, said injection side further comprising a cavity insert adapted to fit within said cavity insert-receiving hole, and (b) an ejection side having a main ejection side frame with a B plate having at least one exposed face and a core insert- receiving hole extending through said B plate opening to its said exposed face, said ejection side further comprising a core insert adapted to fit within said core insert-receiving hole, the improvement wherein said at least one of said inserts comprises a one-piece body stepped along its length and being generally parallelogram-shaped in transverse cross-section.

2. The improvement of claim 1 wherein each of said inserts comprise a one-piece body stepped along its length and being generally parallelogram-shaped in transverse cross-section.

3. The improvement of claim 1 wherein each insert body comprises longitudinally-adjacent sections including a liquid channel section having a pair of mutually-parallel, outwardly-open liquid conduit grooves extending around the periphery thereof.

4. The improvement of claim 1 wherein said at least one of said inserts is generally rectangularly- shaped in transverse cross section.

5. A mold insert for use in a mold plate forming one side of a master frame of an injection molding machine, comprising an insert body having three longitudinally adjacent sections including a locking section, a base section, and a liquid channel section intermediate said locking section and said base section, said liquid channel section having at least two mutually- spaced, outwardly-open liquid conduit grooves extending around the periphery thereof.

6. The mold insert of claim 5 wherein said liquid conduit grooves are mutually parallel.

7. The mold insert of claim 5 wherein each of said body sections is generally cylindrical.

8. The mold insert of claim 5 wherein each of said body sections has four distinct linear side margins.

9. The mold insert of claim 8 wherein each of said body sections is generally a parallelpiped.

10. The mold insert of claim 9 wherein each of said body sections is generally a rectangular parallelpiped.

11. The mold insert of claim 5 wherein said body is a solid, one-piece metal body.

12. The mold insert of claim 8 wherein adjacent side margins are joined by arcuate corner margins.

13. A mold insert for use in a mold plate forming one side of a master frame of an injection molding machine, comprising an insert body comprising three longitudinally adjacent sections including a locking section, a base section, and a liquid channel section intermediate said locking section and said base section, each of said body sections being generally parallelogram-shaped in transverse cross-section, and said liquid channel section having at least one outwardly-open liquid conduit grooves extending around the periphery thereof.

14. The mold insert of claim 13 wherein each of said body sections is generally rectangularly-shaped in transverse cross section.

15. The mold insert of claim 13 wherein each of said body sections has first and second pairs of mutually-parallel linear side margins.

16. The mold insert of claim 14 wherein, for each of said body sections, said first pair of side margins is longer than said second pair of side margins.

17. The mold insert of claim 13 wherein, for each of said body sections, said first pair of side margins is perpendicular to said second pair of side margins.

18. The mold insert of claim 13 wherein for each of said body sections, each of said side margins is joined to adjacent side margins by arcuate corner margins.

19. The mold insert of claim 13 wherein said body is a solid, one-piece metal body.

20. The mold insert of claim 13 wherein said liquid channel section has plural outwardly-open liquid conduit grooves extending around the periphery thereof.