Quick change mold

A mold insert set is provided for use with a mold system having first and second mold bodies, the first and second mold bodies aligning opposite each other during a molding process. Each of the mold bodies has at least one insert receiving region for replaceably receiving an insert of the mold insert set. Each of the inserts has an insert body, a mold cavity formed in the insert body, the mold cavity being for forming an object, and an opening in the mold cavity for aligning with a gas injection region of the mold body in which the insert is received. The gas injection region is where blow gas is introduced to the mold cavity for forming the object.

BACKGROUND OF THE INVENTION

The present invention relates generally to molds, and more particularly to molds for molding plastic bottles.

Extrusion-type blow mold machines are used for blow molding bottles and other plastic containers. These blow mold machines typically have a number of removable molds (for example, 12 or 24). The removable molds are specific to a particular bottle or container and must be changed to produce a different bottle or container. The operation of changing the molds of a conventional extrusion-type blow mold machine can be labor intensive and require a long shut down period. Typically, each mold includes a number of connections and devices that require disconnecting and reconnecting each time the molds are changed. In addition, conventional molds can be very heavy and large, requiring additional manpower and or machinery to move and position.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved mold insert set for use with a mold system having first and second mold bodies, the first and second mold bodies aligning opposite each other during a molding process. Each of the mold bodies has at least one insert receiving region for replaceably receiving an insert of the mold insert set. Each of the inserts has an insert body, a mold cavity formed in the insert body, the mold cavity being for forming an object, and an opening in the mold cavity for aligning with a gas injection region of the mold body in which the insert is received. The gas injection region is where blow gas is introduced to the mold cavity for forming the object.

Other embodiments of the invention provide a mold system for forming at least one object. The system has a first mold body having at least one insert receiving region and at least one gas injection region; a second mold body aligning with the first mold body and having at least one insert receiving region and at least one gas injection region; and a plurality of mold inserts. Each of the plurality of mold inserts has an insert body, a mold cavity formed in the insert body, the mold cavity being for forming one of the at least one object, and an opening in the mold cavity for aligning with one of the gas injection regions. Each of the mold inserts fits into one of the insert receiving regions and the gas injection regions are for introducing blow gas from outside the mold bodies to each of the mold cavities for forming the at least one object.

Other embodiments of the invention provide an extrusion-type blow mold machine having a plurality of two-part molds attached to the machine platens. Each two-part mold has a first mold body having at least one insert receiving region and at least one gas injection region; a second mold body aligning with the first mold body and having at least one insert receiving region and at least one gas injection region; and a plurality of mold inserts. Each mold insert has an insert body; a mold cavity formed in the insert body, the mold cavity being for forming at least one object; and an opening in the mold cavity for aligning with one of the gas injection regions. Each of the mold inserts fits into one of the insert receiving regions and the gas injection regions are for introducing blow gas from outside the mold bodies to each of the mold cavities for forming the at least one object. Utility sources (i.e. air and water) can be connected to the mold body and then either directly or indirectly connected to the mold inserts. Cooling water, for example, can be circulated in the mold body and/or in the mold inserts.

Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology or extrusion process so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.

Embodiments of the invention improve upon the conventional molds for use with, for example, an extrusion-type blow mold machine by providing a smaller and lighter removable element of the mold. The invention permits the removal of only that portion of the mold that needs to be replaced to change the configuration of the bottle or container being produced. Parts of the conventional mold design that are the same regardless of the bottle or container being produced need not be a part of the interchangeable mold element of the invention. As a result, the size and weight of the interchangeable parts of the molds in accordance with the invention are greatly reduced relative to a conventional mold.

The smaller size and weight of the mold inserts of the invention greatly reduces the amount of time needed to change the molds of a molding machine. For example, a wheel-type blow mold machine that has 24 conventional molds requires approximately 50-60 hours to replace and adjust all 24 molds. By using molds in accordance with the invention, this time can be reduced to a total of four hours or less. As a result, the invention can provide an additional two days (or more) of production over the conventional system every time the molds are changed.

As an example of a mold machine in accordance with the invention, a schematic view of a wheel-type blow mold machine10having a plurality (twelve in this example) of molds100arranged around its perimeter is shown inFIG. 1. Each mold100has two mold bodies110that face each other and, when closed against each other, form the complete mold100. A wheel-type blow mold machine is used as an example, but the invention also applies to other types of blow mold machines.

FIG. 2shows a prospective view of an example of mold body110that holds two mold inserts200. Each mold insert is positioned within an insert receiving region120.FIG. 2shows only one mold insert200in position so that insert receiving region120can be more clearly shown. In use, each of the two mold insert regions120contains a mold insert200. Utility sources (such as air and cooling water) are connected to the mold body. Service of these utilities is connected to the inserts either directly or indirectly. The gas injected into the cavities can be through an opening in the inserts. Cooling water can either be circulated through the insert or contained within the mold body, where cooling is provided through conduction through the mold body material.

In the example shown inFIG. 2, each mold insert200is held in position by a locking element150that engages a locking recess220in the upper face of mold insert200. An angled face230of mold insert200(shown inFIG. 4) interacts with an angled face160of insert receiving region120to, along with locking element150, hold mold insert200in position within insert receiving region120. Geometric compatibility would include angled, interlocking, or other nesting configurations as fitment between the insert and mold body.

FIG. 3shows one mold insert200in position in the right insert receiving region120while showing the left insert receiving region120empty. As described above, when the mold is in use both insert receiving regions120contain a mold insert200. Each mold insert200has at least one mold cavity210(in this example, two mold cavities210are shown). In the case where, as shown inFIG. 3, each mold insert200has two mold cavities210, and mold body110holds two mold inserts200, four bottles or containers will be produced with each use of the mold. Although two mold cavities210are shown in each mold insert200in this example, any number of mold cavities and mold inserts can be used. The example shown inFIG. 3is for use with a dual parison wheel-type blow mold machine. While the example inFIG. 3shows two insert receiving regions120, it is noted that any number of insert receiving regions120can be used as long as mold body110is adapted accordingly. Although two mold cavities210are shown in each mold insert200in this example, any number of mold cavities and mold inserts can be used.

FIG. 3shows two gas injection regions130formed in mold body110. As shown inFIG. 2, gas injection regions130align with mold cavities210to produce a continuous cavity including mold cavity210of one mold insert200, gas injection region130and mold cavity210of the other mold insert200. Mold body110also has an ejection region140positioned adjacent to each mold cavity210. In this example, mold insert200has edge pieces240that can be made of a different material (such as copper) that provides slip resistance. In use, a molten plastic tube, or parison, is fed between two opposing mold bodies110as the mold bodies are brought together and closed around the parison. The parison is then blown against the walls of mold cavities210and gas injection region130by, for example, a needle inserted into the parison in the gas injection region130. In the example shown inFIGS. 2-6, two parisons are used, each being blown by a separate needle inserted in the respective gas injection region130.

FIG. 4is a sectional view taken along section line IV-IV inFIG. 3.FIG. 4shows locking element150engaging locking recess220in mold insert200such that mold insert200is pressed into position within insert receiving region120of mold body110. Angled face230of mold insert200engages angled face160of insert receiving region120. Correct positioning of mold insert200is ensured by precise machining of mold insert200and insert receiving region120. It is noted that other types of locking mechanisms can also be used. The inserts can be affixed to the mold bodies by geometric compliance (fitment) between the compatible surface of each entity or by auxiliary components (mechanical or electromechanical, for example), or by a combination of these.

FIG. 5shows a sectional view along section line V-V inFIG. 3. This section is through gas injection regions130and also shows locking element150in the background.

FIG. 6is a top view of the embodiment of the invention shown inFIG. 3. InFIG. 6, the insert receiving region120on the left hand side is empty whereas the insert receiving region120on the right hand side contains mold insert200held in place by locking element150.

FIGS. 7 and 8show an alternate embodiment of the invention in which locking element150is replaced by a locking element350which uses a clamping mechanism that is operable without the use of tools. Locking element350has a handle352which is connected to and operates a hooking loop354which, in turn, engages with a catch356mounted to mold insert200′. By engaging hooking loop354with catch356and pulling down on handle352, pressure is imparted in mold insert200′ and it is held firmly in place in insert receiving region120.

FIG. 8shows one insert receiving region120without a mold insert200′ in place and one insert receiving region120with a mold insert200′ in place. In this example, an insert retention element300is shown associated with each insert receiving region120to hold each mold insert200′ in place. Each insert receiving region120can also be provided with a security lock320for engaging mold insert200′ and holding it in place. Security lock320can be considered a back-up lock to help prevent damage to the mold inserts if the worker who is changing the mold inserts forgets to engage locking element350.

It is to be understood that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention.