Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – And means to form or reshape preform
Reexamination Certificate
2002-01-28
2004-08-31
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
And means to form or reshape preform
C264S255000, C425S123000, C425S127000, C425S129100, C425S576000
Reexamination Certificate
active
06783346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally related to a device and a method for manufacturing articles made of plastic material and, more particularly, toward a device and method for manufacturing brushes and, more particularly, toothbrushes.
2. Description of Related Art
Articles made of plastic material, in particular toothbrushes, are frequently manufactured out of differing materials and are multicolored. In the case of toothbrushes, for example, soft materials are combined with hard materials, wherein the soft materials, for example, form gripping surfaces or flexing points. Toothbrushes of this type, which consist of several material components or which have several colors, are manufactured in special tools.
Known from prior art are various devices and methods for the manufacture of toothbrushes out of several material components. EP 0 0742 090, for example, demonstrates a device, which is based on a rotary table (star wheel tool). In this, individual material components are injected from one side into multi-part cavities, which in certain areas are actively connected with the rotary table situated in a single plane. The articles to be injection molded around are moved by the rotary table from one cavity to the next lying in the plane, wherein they are held in a zone, which only comprises a single material component. All cavities have the same parting plane.
This device has the disadvantage that, because of the cavities located adjacent to one another, it has to be built with very large dimensions and, for this reason, within a single cycle only a few articles can be manufactured. An integration of a device in accordance with this principle into a standard injection molding machine, wherein the half-molds are guided along spars, is uneconomical because the distances between the spars of the injection molding machine are standardised and as a result of this the maximum dimensions are limited.
SUMMARY OF THE INVENTION
It is an objective of the invention to provide a device and a method that makes possible an optimised manufacture of articles made of plastic material with several material components and colors.
The invention is explained in more detail on the basis of a toothbrush. For the specialist it is clear, however, that the invention is not restricted to the manufacture of articles of this type.
Brush bodies of toothbrushes as a rule consist of a handle, which serves to grip the brush, a head, on which the bristles of the brush are affixed and a stem, which connects the handle with the head.
Toothbrushes as well as other articles made of plastic, which consist of several components or colors, today are manufactured by injection molding. In doing so, the individual colors and material components are injected into cavities one after the other, in which in part intermediate products to be injection molded around have been placed. The articles are moved from one cavity to the next by means of mechanical aids, in that they are held in a zone suitable for this, which only comprises a single material component. A brush body of a toothbrush, for example, is preferably held in the zone of the head of the brush while it is moved from one cavity to the next, because this zone as a rule is not equipped with several materials. Through the choice of the materials and in particular of their melting points, it is guaranteed that a component is not damaged, by melting in an uncontrolled manner, while being injected around with a further component.
The half-molds of an injection mold for manufacturing injection molded components are usually attached to mounting plates in an injection molding machine. A first half-mold is fastened to a fixed mounting plate and a second half-mold is fastened to a movable mounting plate, which in most instances is guided by four spars. Because the two half-molds are arranged between the spars of the Injection molding machine, their maximum expanse is restricted by the distance between the spars. Today's molds for the manufacture of articles made of plastic with several material components are based on star wheel tools with rotary tables on which the part products are moved out of one cavity into another one. In doing so, the cavities are arranged adjacent to one another in a circle on a plane. In order to get from one cavity to the next one, the articles or the cavities are moved around the axis of the rotary table, which is arranged parallel to the spars of the injection molding machine. A significant disadvantage of this arrangement is that the number of articles is massively limited because of the tight space conditions.
The invention divulged here demonstrates a device and a method, which significantly improves the manufacturing operation for articles made of plastic with several material and/or color components. In contrast to methods known from prior art, the individual material or color components are not manufactured in one plane on a rotary plate (star wheel tool), but rather manufactured in a tool with several levels (parting planes). This is a further development of an injection molding technology of the same applicant, which in part is already known from WO 99/28108.
The invention divulged here described in a simplified manner is based on the fact that, between a geographically fixed first and a movable second half-mold, each of which comprises at least one half-cavity, a third mold carrier is arranged as rotatable around an axis and displaceable at an angle to this axis. The third mold carrier serves to accommodate at least one third and one fourth half-mold with at least two half-cavities, which half-cavities of the third and fourth half-mold are actively connectable alternatingly with the first or second half-mold. These further half-molds comprise means to put in place articles (intermediate products) in the area of the further half-molds from one half-cavity to the other so that they can be injection molded around with another material component in the other cavity on several sides. These means preferably are slides, which are at least partially integrated into a cavity.
The rotational axis of the third mold carrier preferably is arranged substantially vertically to the direction of movement of the movable second mold carrier and additionally translatorily displaceable in the same direction as the moveable second half-mold. The third and the fourth half-molds are affixed to two opposite sides of the third mold carrier and, in the closed condition of the complete mold, alternatingly act in conjunction with the first or with the second half-mold in two parting planes so that on every side of the movable mold carrier at least one cavity is formed by the half-cavities of the half-molds. By means of this injection molding of material components in several planes it is achieved that, in contrast to the star wheel tools known from prior art, more articles injection molded around on several sides are capable of being manufactured with one tool. The closing forces necessary for sealing the mold, as a result of the several comparatively smaller separating planes, are correspondingly smaller.
The movements of the second half-mold as well as of the third and fourth half-molds attached to the rotatable mold carrier are preferably coordinated with one another. The coordination can be designed as follows. When opening the mold the second half-mold is displaced translatorily relative to the first half-mold. Simultaneously, the mold carrier arranged to be movable with the third and the fourth half-mold, which in the closed condition are arranged between the first and the second half-molds, is moved translatorily with about half the speed of the second half-mold in the same direction as the second half-mold, so that the two separating planes are opened symmetrically. The movement is carried out to such an extent that the movably arranged mold carrier with the third and the fourth half-molds is capable of being rotated around its axis, so that the articles from a first material component are capable of be
Armbruster Rainer
Bodmer Werner
Foboha GmbH
Heitbrink Tim
Rankin, Hill Porter & Clark LLP
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