Stack Mold Carrier Mounted on Linear Bearings

The present invention relates to an improved stack mold center section carrier for a molding machine.

Stack mold systems for molding articles are known in the prior art. One such stack mold system is shown in U.S. Pat. No. 4,207,051 to Wright. The Wright stack mold system has tiebars which pass through the mold plates, thereby supporting them directly. Removing the molds from the machine requires the tiebars to be withdrawn. This is a time consuming process which requires additional space behind the molding machine's clamp to accommodate the tiebars in their withdrawn positions.

Early stack mold carriers were attachments to the mold center section that supported it in the molding machine and allowed the center section to slide along the machine's tiebars. U.S. Pat. No. 4,408,981 to Brown shows a carrier riding on the lower tiebars. Removal of the mold also required removal of the carriers as they were not attached to the machine. This was an added complication taking more time to change the mold.

U.S. Pat. No. 4,929,166 to DiSimone et al. shows a similar carrier riding between the upper and lower tiebars so that removal of the mold leaves the carrier in place between the tiebars on the machine. The carrier remains attached to the machine by virtue of the half shoe bearings acting on both the upper and lower tiebars. This saved time when a stack mold was removed and replaced with another stack mold, but did not solve the problem when the incoming mold was not a stack mold. In that case, the carriage assembly had to be dismounted from the machine by taking it apart.

There is a need for a mold carrier to which a stack mold can be quickly attached and yet remains safely installed in the machine when the stack mold is removed, and itself can be easily removed from the machine if required.

Accordingly, it is an object of the present invention to provide an improved mold carrier assembly for the mold center section of a stack mold.

It is a further object of the present invention to provide a mold carrier assembly as above that is stable when the mold center section of a stack mold is removed.

It is yet another object of the present invention to provide a mold carrier assembly as above which is easily aligned with the platens.

It is still another object of the present invention to provide a mold carrier assembly as above which can be quickly and conveniently removed if necessary.

The foregoing objects are attained by the improved mold carrier assembly of the present invention.

In accordance with the present invention, a mold carrier assembly for supporting a mold center section of a stack mold is provided. The mold carrier assembly has a pair of mold supports to which the mold center section can be attached. Each mold support is movable along a linear rail attached to the base of a molding machine and has at least one block containing a linear bearing mounted thereto for engaging the linear rail. Each mold support further includes a linkage assembly for connecting the mold support to other platens so as to synchronize movement of each mold support with movement of at least one other platen.

The present invention also relates to a molding machine incorporating said mold carrier assembly. The molding machine comprises a base having lateral support structures with each of said lateral support structures having at least one linear rail mounted thereon. The molding machine further has a stack mold system including a stationary platen fixed to the base, a movable platen, and a carrier assembly for supporting a mold center section. The carrier assembly comprises two mold supports with each of the mold supports having at least one block containing a linear bearing mounted thereto for allowing the respective mold support to slide along the at least one linear rail on a respective one of the lateral support structures.

Other details of the mold carrier assembly and the molding machine of the present invention, as well as other objects and advantages attendant thereto are set forth in the following detailed description and the accompanying drawings, in which like reference numerals depict like elements.

FIG. 1 is an isometric view of a machine base and platen assembly with a stack mold carrier assembly in accordance with the present invention installed;

FIG. 2 is an isometric view of a linear bearing track and mold carrier pillars;

FIG. 3 is a side view of a carrier assembly pillar with a linkage assembly mounted;

FIG. 4 is a top view of the carrier assembly pillars with the linkage assemblies mounted; and

FIG. 5 is an end view of the carrier assembly pillars with linkage assembly mounted.

Referring now to the drawings, FIG. 1 illustrates a molding machine 10 with the stack mold carrier assembly 12 of the present invention. The molding machine 10 has a clamp base 14 which includes two lateral support structures 16 and 18. The molding machine 10 further has two platens 20 and 22 to which molds (not shown) are attached. Platen 20 is a fixed or stationary platen, while platen 22 is a movable platen which rides on linear bearings 24 that engage fixed linear rails 26 fastened to the support structures 16 and 18. The molding machine 10 also includes means (not shown) for moving the platen 22 between mold closed and mold opened positions. The means for moving the platen 22 do not form part of the present invention and thus are not described in detail. Any suitable platen moving means known in the art may be used in the machine 10 to move the platen 22 between the mold closed and mold open positions. Tiebars 28 are provided to add structural support to the machine and extend from the stationary platen 20 to a mold clamping unit (not shown) or some other support (not shown). In the molding machine 10 of the present invention, the tiebars 28 are not used to align or support the moving platen 22 or the stack mold carrier assembly 12.

As shown in the drawings, the stack mold carrier assembly 12 for supporting a center mold section 56 comprises two mold supports or pillar castings 30 positioned on the support structures 16 and 18. Referring now to FIG. 2, each pillar casting 30 has a vertical post portion 32 that contains recesses 34 to accommodate keys (not shown) and through holes 36 for bolts. Both keys and bolts are used to align and fasten each pillar casting 30 to a respective side of a center mold section 56 (shown in dotted lines) of the stack mold in a known fashion. Each pillar casting 30 has a base support 38 to which is fastened one or more blocks 40 containing linear bearings that engage and run a respective linear rail 26 mounted to one of the side supports 16, 18. The linear rail 26 may be the same rail used to guide the moving platen 22 or may be a second rail mounted parallel to the linear rail used to guide the moving platen 22 and offset outboard to provide a dedicated alignment means for the stack mold carrier assembly pillar casting 30. This latter approach can be particularly useful if the support portion 38 must overlap the moving platen position when the moving platen 22 is in a mold closed position.

Each pillar casting 30 has a third portion, a boss 42, to which a carrier linkage assembly 44 is rotatably mounted. Any suitable connection means known in the art may be used to rotatably mount the linkage assembly 44 to the boss 42. The linkage assembly 44, as shown in FIGS. 3-5, has a propeller 46 rotatably mounted to the boss 42. The propeller 46 has links 48 and 50 rotatably mounted to its ends. Link 48 is rotatably mounted to the stationary platen 20, while link 50 is rotatably mounted to the moving platen 22. The motion of the moving platen 22 between mold closed and mold open positions causes the linkage assembly 44 to move each pillar casting 30 along a respective one of the rails 26 and maintain each pillar casting 30, and hence the center mold section (not shown), midway between the platens 20 and 22 for the entire platen stroke. This is a conventional and well known method of mold carrier movement.

Copending U.S. patent application Ser. No. 09/054,692, filed Apr. 13, 1998, now U.S. Pat. No. 6,027,681, which is incorporated in its entirety by reference herein, assigned to the assignee of the instant application, teaches a method where links of unequal length can be used to control the motion of the mold center section differently. If desired, the linkage system shown in the '692 patent application can be used in lieu of the linkage assembly 44.

In the event that the center mold section (not shown) of the stack mold assembly is removed from the machine 10 and from the stack mold carrier assembly 12, the carrier assembly 12 remains attached to the machine 10 and will not fall inward or outward because the support base 38 of each respective pillar casting 30 is firmly held by the linear bearing(s) in the block(s) 40 on a respective rail 26. Links 48 and 50 attached to the platens 20 and 22, respectively, also contribute to the stability of each pillar casting 30, and hence the carrier assembly 12, when the center mold is removed. As can be seen from the foregoing description, the design of the stack mold carrier assembly of the present invention provides a convenient and safe arrangement for loading and unloading stack molds.

A second advantage to the carrier assembly design of the present invention is that the pillar castings 30, and thus the carrier assembly 12, are easily aligned with the platens 20 and 22 as the pillar castings 30 share a common mounting means, namely the rails 26 attached to the machine base 14. This design avoids time consuming shimming to properly align the carrier assembly with the platens.

A third advantage to the carrier assembly design of the present invention is the ease of removal, when necessary, of each carrier assembly 12 from the machine 10. This can be quickly and conveniently achieved by removing the bolts 52 fastening the ends of the links 48 and 50 to the platens 20 and 22 and the bolts 54 securing each pillar casting 30 to the linear bearing block(s) 40. Each carrier assembly 12 can then be lifted away using a crane. Tiebar removal, or carrier disassembly, is not required in order to dismount each carrier assembly unlike earlier design.

It is apparent that there has been provided in accordance with the present invention a stack mold carrier mounted on linear bearings which fully satisfies the means, objects, and advantages set forth hereinbefore. While the present invention has been described in the context of specific embodiments thereof, alternatives, modifications, and variations will become apparent to those skilled in the art after reading the foregoing description. Therefore, it is intended to embrace such alternatives, modifications, and variations as fall within the broad scope of the appended claims.