MXPA00003221A - Molding apparatus with downwardly moving mold tunnel - Google Patents

Abstract

A plastic molding apparatus comprises an extruder (3) and a vertically extending mold tunnel (20) formed by mated mold block sections which are moved downwardly through the mold tunnel (20) as part of a continuous looping of the mold block sections around the apparatus. The mold tunnel has an upwardly opening mouth and the extruder (3) feeds a stream of molten plastic (13) downwardly into the mouth of the mold tunnel (20).

Description

MOLDING APPLIANCE WITH MOLDED TUNNEL THAT MOVES DOWN FIELD OF THE INVENTION The present invention relates to a plastic mold apparatus of the type in which a continuous stream of molten plastic is fed to a moving mold tunnel.

BACKGROUND OF THE INVENTION A known molding apparatus is one in which an extruder feeds a continuous stream of molten plastic into a horizontally extending mold tunnel. This type of apparatus is very beneficial, for example, in a plastic tube formation. However, it is not well suited for the formation of plastic articles with irregular shapes which require variable placement of the plastic feed to the mold tunnel. Although very rare extruders operating vertically are known, as described in U.S. Patent 3,519,705 and U.S. Patent 2, 134,844A. The extruders in both of these patents operate using blow molding and as such the product forming regions known as mold tunnels must be sealed. In addition, the extruders in these two patents are trapped within the upper end of the mold tunnels which prohibits the positional adjustments of the extruder relative to the mold tunnel.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an apparatus for plastic molding comprising an extruder and a vertically extending mold tunnel formed by tight mold block sections which move down through the mold tunnel as part of a continuous circuit of the mold block sections around the apparatus. The mold tunnel has a tunnel opening that opens upwards and the extruder feeds a molten plastic stream down to the mouth of the mold tunnel. The apparatus of the present invention is particularly useful in the molding of articles of irregular shapes because either the mold tunnel and / or the extruder can be easily adjusted in position while maintaining the feeding of the plastic from the extruder to the mold tunnel fulfilling the requirements to form plastic parts of irregular shapes.

BRIEF DESCRIPTION OF THE DIAMETERS The foregoing as well as other advantages and aspects of the present invention will be described in greater detail in accordance with the preferred embodiments of the present invention in which: Figure 1 is a side view of a molding apparatus according to a preferred embodiment of the present invention; Figure 2 is an enlarged side view of the upper mold tunnel region of the apparatus of Figure 1; Figures 3 and 4 are sectional views along lines 3-3 and 4-4 respectively of Figure 2.

DETAILED DESCRIPTION ACCORDING TO THE PREFERRED MODALITIES OF THE PRESENT INVENTION Figure 1 shows a plastic molding apparatus generally indicated at 1. This apparatus comprises an extruder 3 feeding a molten stream of plastic 13 to a product forming region indicated generally by 15. In the particular embodiment shown, the product forming region comprises a pair of circuit carrier tracks 17 and 19 endless side by side. A plurality of mold block sections are secured around each of the carrier paths. The carrier paths move the mold block sections to a central mold tunnel 20 where the mold block sections on one track close and mate with the mold block sections on the other carrier path. As will be seen in Figure 1, the mold tunnel 20 extends vertically and the mold block sections when matched together move downwardly through the mold tunnel. The mouth of the tunnel is at the upper end of the mold tunnel where the plastic stream 13 is fed into the mold tunnel. Each of the tracks is driven by a gear 18 at one end of each track. Figure 2 shows the drive gears 18 as being at the upper ends of the tracksIn a continuous circuit, however, it is also possible to provide the driving gears at the lower ends of the tracks. It may also be desirable to provide drive gears at each end of both tracks. The movement of the tracks is extremely efficient and requires very little in the form of a driving force. As will be understood from the drawings, each track with its mold blocks is balanced from side to side such that the amount of lifting required to move the mold block sections upward on one side of each track is effectively compensated by the weight of mold block sections that move down on the other side of each track. A number of aspects occur as a result of the vertical orientation of the apparatus of the present invention. One of these advantages is that the apparatus takes up less floor space than an extrusion type molding apparatus operating horizontally conventionally. Even more important for the present invention is the ease with which the extruder can be aligned with the mold tunnel and more specifically with the mouth of the mold tunnel. In addition, the extruder feeds through gravity into the mold tunnel which requires less working pressure in the extruder. In addition, the actual extruder nozzle 6 of the extruder does not have to be trapped inside the mold tunnel but rather can be remotely positioned thereto as shown in Figure 1 which again increases the ability to align the extruder with the mold tunnel in case any movement is required as described below. In such a case, the molding will preferably be achieved by vacuum inside the mold tunnel.

The extrusion apparatus 1 is well suited particularly for the formation of irregularly shaped articles such as bottles, automotive parts or any other type of molded plastic article. In the embodiment shown, the carrier tracks 17 and 19 are, as described above, used to move a plurality of sections of mold blocks. These mold block sections include different sets of mold block sections that equal each other in the mold tunnel. The different sets of sections of mold blocks can have different configurations according to the shape of the plastic article to be formed. For example, the mold block section 21 on track 17 is paired in the mold tunnel with the mold block section 25 on track 19 as shown in Figure 3 of the drawings. The mold block section 21 has an inner mold cavity 22 and the mold block section 25 has an inner mold cavity 26. As these two sections of mold blocks are carried by their respective carriers to the upper end of the mold tunnel where they are closed between them as shown in Figure 3, the mouth of the mold tunnel is formed by pairing the cavities 22 and 26 of the mold. The molten parison stream 13 is then fed from the extruder 3 to the mouth of the mold tunnel which has its shape and which is in a specific low position of the extruder. The shape and placement of the tunnel mouth is not the same, however, as shown in Figure 3. For example, tracks 17 and 19 are provided with a different set of sections 23 and 27 of mold blocks. which are also matched together in the mold tunnel. The mold block section 23 has an interior cavity 24 while the mold block section 27 has an interior cavity 28 as shown in Figure 4 of the drawings. When these two sections of mold blocks are carried around the upper part of the mold tunnel they will form the mouth of the mold tunnel in a different way than the one shown in Figure 3. In addition, the placement of the mouth of the tunnel of The molds have changed in a horizontal plane from the position of Figure 3 to Figure 4. Note that the change, as evidenced by the division line 22 in Figure 2 of the mold block sections, is gradual such that the The entire mouth of the tunnel is exposed. In view of the above described change of the mouth of the tunnel it is important that the apparatus be capable of adjustment to ensure that the plastic flow of the extruder goes directly to the mouth of the mold tunnel regardless of its shape and position. This can be achieved in a number of different ways described later on later. However, it should be noted at this point that each of the adjustments is made easily due to the vertical orientation of the mold tunnel, the extruder separation from the mold tunnel and the ability of the extruder to feed down the mold tunnel. As will be seen in Figure 1, the extruder 3 is held in its downward directed position by an extruder support 9. The head of the extruder itself can be secured in an adjustable manner as indicated in four to the support 9 which allows horizontal or side-to-side adjustment of the extruder head as indicated by arrows 5 and 7. It is also possible to have the base of the extruder support 9 seated in the adjustment members 1 1 on the base surface for the support. This would again provide a side-to-side adjustment of the extruder head. Another method for ensuring alignment of the plastic flow to a variablely positioned tunnel is by making the tracks 17 and 19 carrying movable mold blocks in a horizontal plane. In the embodiment shown, the two tracks are supported by support beams 33 of a carrier support 29. The carrier paths are adjustable along the beams 33 in the direction of the arrows 35 and 37. During the operation of the mold, the two tracks will move simultaneously with one another to keep the mold tunnel closed. However, during stopping times, either or both of the carrier paths are movable along the beams 33 independently between them in opposite directions to separate the two tracks for cleaning and / or replacing the mold block sections. As also shown in Figure 1, the complete support 29 for the mold block holders can be seated on an adjustable base 31 which allows side-to-side movement of the support 29 relative to the base surface. In a further embodiment of the present invention, a parison guide 39 is provided between the nozzle 6 of the extruder 3 and the mouth of the mold tunnel. This guide is movable again from side to side in the horizontal plane as indicated by arrows 41 and 43. The guide 39 has an opening 40 through the guide. The parison flows through and is guided by the opening 40. When the guide is adjusted in a side-to-side direction, a corresponding adjustment is made in the flow direction of the extruder parison. This adjustment will correspond to the placement of the mouth opening for the tunnel which in turn depends on which particular assembly of paired block sections are at the upper end of the tunnel. When working with the guide 39, it may be desirable to provide a fluid flow around the edges of the guide to prevent the parison from sticking to the guide. Adjustment of the alignment of the extruder's parison flow to the tunnel mouth regardless of which medium is used to make the adjustment is dictated by a controller within the system which is pre-programmed to make the appropriate adjustments in the moments appropriate. Another aspect of the present invention is that the speed of the paired mold block sections through the mold tunnel can be varied by changing the speed of the carrier paths. This in turn changes the thickness of the formed plastic or the diameter of the part formed inside the mold tunnel without changing the plastic flow of the extruder. As alternatives, the plastic flow rate of the extruder can also be varied to change the wall thickness of the product or the diameter of the product by means of adjustable spaces in the extruder or by the use of adjusting screws as are known in the molding art. . Although several preferred embodiments of the present invention have been described in detail, it will be appreciated by those skilled in the art, that variations may be made without departing from the spirit of the invention or the scope of the appended claims.

Claims (9)

1. REVIVAL NAMES 1. A plastic molding apparatus comprising an extruder and a vertically extending mold tunnel formed by paired mold block sections that move down through the mold tunnel as part of a continuous circuit of the mold. the sections of mold blocks around the apparatus, the apparatus being characterized in that the mold tunnel has an open mouth at the upper end of the tunnel, the extruder has a nozzle which is directed to, without being trapped within, the mouth of the tunnel of molds and the apparatus uses vacuum to form the product inside the mold tunnel.
2. 2. An apparatus for plastic molding as claimed in claim 1, wherein said sections of mold blocks include sets of paired mold block sections of different configurations and wherein said tunnel mouth changes to different positions in a plane horizontal according to which set of mold blocks is present at a particular moment in the mouth of the tunnel, and said apparatus which is adjustable to provide alignment of the plastic stream with the tunnel mouth in the different positions of the tunnel mouth .
3. 3. A plastic molding apparatus as claimed in claim 2, wherein said sections of mold blocks are moved by carrier means which are mounted on and horizontally adjustable from a support by said carrier means.
4. 4. An apparatus for plastic molding as claimed in claim 3, wherein said carrier means comprises a pair of carrier paths of mold blocks from side to side which are horizontally adjustable together with respect to said support.
5. 5. An apparatus for plastic molding as claimed in claim 4, wherein at least one of said carrier paths of mold blocks is independently adjustable on said support relative to the other of said carrier paths of mold blocks.
6. 6. An apparatus for plastic molding as claimed in claim 2, wherein said extruder is horizontally adjustable.
7. 7. An apparatus for plastic molding as claimed in claim 2, including an adjustable guide that is between said extruder and said mold tunnel and that provides horizontal adjustment of the plastic stream of said extruder to the tunnel mouth.
8. 8. An apparatus for plastic molding as claimed in claim 2, wherein said carrier means is adjustable in speed according to which set of sections of mold blocks is present at the upper end of said mold tunnel.
9. 9. A plastic molding apparatus as claimed in claim 2, including a controller that is programmed to automatically adjust said apparatus to maintain the supply of molten plastic stream to the tunnel mouth in the different positions of the same .