MX2008005562A - Machine for compression molding closure shells - Google Patents

Abstract

A machine for compression molding plastic closures includes a support (39) mounted for rotation around an axis, and a plurality of compression molds (52) on the support at angularly spaced positions around the axis. Each of the molds includes a male mold section (54) and a female mold section (56), at least one of which is movable with respect to the other between a closed position to form a compression mold cavity and an open position spaced from each other. The male mold section includes a mold core (60) and a stripper sleeve (80) surrounding the mold core for movement both rotationally and axially of the mold core. A first screw drive (91) couples the female mold section to the stripper sleeve for rotating the stripper sleeve around the mold core as the at least one mold section is moved between the closed and open positions. A second screw drive (83) couples the stripper sleeve to the support to move the stripper sleeve axially over the mold core as the stripper sleeve is rotated around the core. The stripper sleeve thus rotationally and axially removes a closure shell molded around the core as the at least one mold section is moved with respect to the other from the closed toward the open position.

Description

MOLDING MACHINE FOR COMPRESSION OF CLOSURE CLADDING FIELD OF THE INVENTION The present invention relates to a compression molding machine for closing coatings.

BACKGROUND OF THE INVENTION [0002] Typically, compression molding machines of closure liners include a turret or carousel that rotates about a vertical axis. A plurality of molds around the periphery of the carousel includes a male mold section and a female mold section, which are aligned along vertical axes parallel to the axis of rotation. The cams drive one or both of the mold sections of each pair between a separate open position, in which the molded closure liner is disassembled or separated from the male mold section and a load of plastic material is placed in the section of female mold, and a closed position in which the male mold section and the female mold section are joined for compression molding of the load in order to form the closure liner. U.S. Patents illustrating machines of this type for compression molding of plastic closure liners include 5,670,100; 5,989,007; 6, 074,583; and 6, 478,568. REF. 192734 When compression molding of closure liners is performed on machines of this type, the liner is usually separated from the male mold core by means of a sleeve engaging the edge of the closing skirt. The sleeve and / or the core are moved in axial direction with respect to each other, so that the closing skirt is effectively pushed out of the core. This type of disassembly or separation action is satisfactory for many applications, although it is not satisfactory for applications that require precise control and / or contouring of internal thread segments on the closure liner, such as in autoclave applications in which the closure must remain on the container finish under conditions of high temperature and pressure. In applications of this type, the closure must be separated from the soul by turning the closure out of the core. U.S. Patent No. 6, 706,231 discloses a vertical axis carousel-type machine for the compression molding of closure liners, in which a cam-operated ball screw arrangement rotates the mold core to decouple the mold core of the closure lining and separating the lining of the core.

BRIEF DESCRIPTION OF THE INVENTION The present description involves a number of aspects or inventions, which could be implemented separately or in combination with each other. A plastic closure compression molding machine according to one aspect of the present invention includes a support mounted for rotation about an axis and a plurality of compression molds on the support in angularly spaced positions about the axis. Each of the molds includes a male mold section and a female mold section, at least one of which can be moved with respect to the other between a closed position forming a compression mold cavity and an open position spaced apart from each other. . The male mold section includes a mold core and a spacer sleeve that surrounds the mold core for movement, both in the rotational and axial directions of the mold core. A first spindle drive couples the female mold section with the spacer sleeve for rotation of the spacer sleeve around the mold core as at least one mold section is moved between the closed and open positions. A second spindle drive engages the spacer sleeve in the holder to move the spacer sleeve in the axial direction through the mold core as the spacer sleeve is rotated about the core. In this way, the separating sleeve removes rotationally and axially a closure liner molded around the web as at least one mold section is moved with respect to the other from the closed position to the open position. The support could comprise a horizontal wheel as in a carousel-type compression molding machine or a vertical wheel that can rotate about the horizontal axis. At least one mold section could be a cam driven between the open and closed positions as a function of rotation of the support about its axis.

BRIEF DESCRIPTION OF THE FIGURES The description, together with the objectives, features, advantages and additional aspects thereof, will be better understood from the following description, the appended claims and the accompanying figures, in which: Figure 1 is a front elevation view of a compression molding machine according to one embodiment of the present invention; Figure 2 is a side elevational view of the compression molding machine illustrated in the Figure 1; Figures 3A-3D together form a sectional view taken, substantially, along the line 3-3 in Figure 2; Figures 4-9 are fragmentary sectional views illustrating a mold of the machine of Figures 1-2 in sequential stages of operation; and Figure 10 is a front view of the spacer sleeve in the machine of Figures 1-9.

DETAILED DESCRIPTION OF THE INVENTION Figures 1-2 illustrate a machine 20 for compression molding of plastic closure liners according to one embodiment of the present disclosure. The machine 20 includes a wheel 22 mounted on an axle 24 between the separate supports 26, 28. The axle 24 is coupled by means of a pulley 30, a belt 32 (Figure 2) and a gearbox 34 with the engine 36 for the rotation of the shaft 24 and the wheel 22 about the horizontal axis. The wheel 22 includes a bushing (which could be part of the shaft 24) and a support 39 that extends radially from the hub. The support 39 could comprise a solid disc, or the like, or more preferably, a plurality of support rays extending in the radial direction and are separated in axial position 38. Preferably, each support beam 38 is hollow » at its outer end, as best seen in Figures 3A-3D. A rod 40 is slidably supported, such as by the sleeve bearings 42, within the outer or hollow end of each ray 38. A cross bar 50 is engaged with the outer end of each rod 40, so that it is preferred that the combination of the rod 40 and the bar 50 is of a generally T-shape as seen from the tangential direction in Figure 3A. A plurality of radially spaced external supports 44, 46 is provided on the spokes 38, preferably on each axial side of each ray. The radially inner supports 44 on the series of spokes are preferred to form circumferentially continuous support rings, as best seen in Figure 2. Preferably, the radially outer supports 46 are circumferentially spaced apart from each other. A plurality of angularly spaced molds 52 is located around the periphery of the wheel 22, preferably, but not necessarily, on both sides of the wheel. Each mold 52 is placed between the supports 44, 46 on the associated beam 38 and one end of the cross bar 50 on the rod 40. Preferably, all the molds 52 are identical. To the extent described in this manner, the machine 20 is similar to that described in the United States Co-pending Application (Attorney File 18565) entitled "Compression Molding Machine", the description of which is incorporated herein by reference. reference. Preferably, each mold 52 includes a first radially inner mold segment or section 54 and a second mold segment or section 56 in external radial alignment with the associated first mold section 54. (Unless otherwise indicated, Address words such as "radial", "tangential", "interior" and "exterior" are employed by way of description and not as a limitation with respect to the axis of rotation of the wheel 22). In the preferred embodiments of the disclosure, up to the range included in a vertical wheel machine, the first radially inner mold section 54 is a male mold section and the second radially outer mold section 56 is a female mold section., although these mold sections could be inverted according to the broader principles of the description. The male mold section 54 includes a mold core 60 having a convoluted core tip 62 to form the desired interior geometry of the closure liner. In the same way, the female mold section 56 includes a cavity insert 64 mounted through a support block 66 on a cross bar 50. The insert 64 has a geometry that forms the desired outer contour of the closure liner. The cam rollers 68, 70 are mounted on the supports 72 which extend from the cross bar 50 for their clutch with the cams 74, 76 for the purpose of moving the female mold sections 56 radially inwards and towards outside with respect to the male mold sections 54 as a function of rotation of the wheel 22 about its axis. To the extent described in this manner, the constructions of the male mold and female mold sections, and the mechanism for opening and closing the mold sections, are similar to those described in the US Copending application, described before. The male mold section 54 also includes a spacer sleeve 80 that surrounds the mold core 60. The spacer sleeve 80 can move in the axial direction with respect to the mold core 60 (ie, in the direction of the axis of the mold core) and in circumferential or rotational shape around the outer surface of the mold core. The spacer sleeve 80 is carried within the support 46 by a sleeve bearing 82 adjacent the radially inner end of the sleeve 80 (with respect to the axis of rotation of the wheel). The external threads adjacent the inner end 84 of the spacer sleeve engage an internally threaded collar 86 which is carried by the support 46 to form a spindle drive 83, as will be described. At the radially outer end of the spacer sleeve 80, a circumferential series of teeth 88 (FIG. 10) is provided to engage with the axial edge of the molded skirt of the closure liner, as will be described. In intermediate position of the ends of the spacer sleeve, a circumferential series of gear teeth 90 is provided, which extend in the axial direction of the spacer sleeve in its entirety around the outer surface of the spacer sleeve and in a substantial portion of the length of the separator sleeve. That is, the gear teeth 90 are of the shape of a series circumferentially spaced apart from grooves or grooves extending in the axial direction around the outer surface of the spacer sleeve 80, preferably between the intermediate portion of the spacer sleeve and the end portion. No. 84. A spindle drive 91 (see Figure 4) engages the female mold section 56 with the spacer sleeve 80. The spindle drive 91 includes a ball spindle 92 having a ball nut 94 and a shaft. of ball screw 96. The ball nut 94 is coupled with the ball screw driving wheel 98 which is carried by the mold section 56 for limited movement in the axis direction of the shaft 96, which is parallel although it is is displaced from the axis of the mold 52. The opposite end of the ball screw shaft 96 (the radially inner end with respect to the axis of rotation of the wheel 22) is coupled with a drive gear 100 which is ngranado with the gear teeth 90 in the separator sleeve 80. Preferably, the ball screw shaft 96 is carried by rotary bearings 102 on the support 46. The ball screw driving wheel 98 is operatively connected to the section of mold 56 by means of a lost motion or idle displacement coupling 104 (see Figure 4). The lost motion or idle displacement coupling 104 includes a rod 106 connected at one end radially internal with the support 46 and slidable in a bearing 108 carried by the mold section 56. The rod 106 has a groove 110 with an angled cam surface 112 at its radially outer end. The ball screw drive wheel 98 is slidably carried within a sleeve 114 on the mold section 56. The drive wheel 98 has a detent receptacle extending in the lateral direction 116 which is opposite the slot 110 in the rod 106. A retainer ball 118 is captured in the holes 120 in the sleeve 114 between the rod 106 and the drive wheel 98. In operation, as the wheel 22 rotates in the clockwise direction of rotation in Figure 2, mold loads of plastic material are sequentially placed through the mold loading positioning mechanism 124 within the inserts 64 of the mold sections 56. During the continuous rotation of the wheel, the mold sections are closed by the cam 74 and the mold load is compression molded to form a closure liner. When the mold 52 engages again with the cam 76 (FIG. 3A) from the direction of clockwise rotation of the hands (FIG. 2), the mold section 56 is pulled from the mold section 54 to open the mold. mold, and the molded coating is separated from the mold core and is removed by a molded part removal device 126 (Figure 2). The separation of the molded closure liner from the mold core is achieved by simultaneous rotation of the molded closure while being pushed in the axial direction over the molded closure using the spacer sleeve 80 as will be described below. Figures 4-9 illustrate movements in a mold 52 from the fully closed position of Figure 4, in which the closure liner is molded, through the positions of Figures 5 and 6 towards the position of Figure 7, in which the mold is completely open, through the position of Figure 8 to the position of Figure 9, in which the mold is almost completely closed. Between the positions of Figures 4 and 5, the mold section 56 is moved downwardly relative to the support 39, so that the ball 118 begins to be pulled downwardly into the slot 110. (The term "downward" in Figures 4-9 it would be radially outward in the preferred but exemplary construction of the vertical wheel of Figures 1-2). However, the initial movement of the mold sections is accommodated by the core support springs 122 (Figure 3C), so that the mold cavity still does not start to open. The further downward movement of the mold section 56 (Figures 5-6) begins to open the mold cavity, and carries the ball 118 towards the clutch with the cam surface 112 of the slot 110. The ball 118 is moved in a eccentric towards the detent receptacle 116 of the ball screw driving wheel 98 (Figure 6), so that further downward movement of the mold section 56 (Figures 6-7) displaces the drive wheel 98 downward with respect to the support 39. This downward movement of the drive wheel 98, and the ball nut 94 carried by the drive wheel 98, rotates the shaft 96 and the gear 100 so as to be able to rotate the spacer sleeve 80 around the core 60. The rotation of the spacer sleeve 80 around the core 60 also functions through the spindle drive 83 to move the spacer sleeve 80 in the axial direction over the core 60. The teeth 88 (FIG. 10) on the spacer sleeve 80 engage with the free end of the skirt. n closure, so that the axial and rotational movement of the spacer sleeve on the web decouples the molded closure skirt of the core tip 62. The pitch of the spindle drive 83 is the same as the pitch of the thread segments on the closing skirt. The thread segments and any other configurations inside the closure skirt are protected from damage or distortion that could otherwise occur if the closure liner were simply pushed in the axial direction away from the mold core. When the closure liner has been uncoupled from the mold core, it is captured and removed by the device 126 (Figure 2), which can be of any suitable type. Once the mold load is placed in the mold section 56, the section 56 is moved from the fully open position of Figure 7 through the positions of Figures 8 and 9 to the fully closed position of Figure 4 As the mold section 56 moves to the position of Figure 8, the ball 118 is pushed back into the slot 110 of the rod 106. The upward movement of the drive wheel 98 rotates the shaft 96, the gear 110 and the spacer sleeve 80, so that the spacer sleeve is returned to its initial position when the mold is closed. The teeth 90 in the spacer sleeve 80 are in the form of elongated ridges to allow axial movement of the spacer sleeve during the separation operation (Figures 6-7). In this way, a compression molding machine has been described that completely satisfy all the objectives and goals previously indicated. The machine has been described in conjunction with a currently preferred embodiment, and a number of modifications and variations have been discussed. Other modifications and variations will be suggested easily by themselves by persons of ordinary skill in the art in view of the above discussion. For example, although the machine has been described in conjunction with a vertical wheel machine, it will be understood that the description in its broader principles would be applied equally in vertical axis carousel type machines. In this machine, the molds 52 would be mounted on the axes parallel to the axis of the carousel, and the mold segments 56 and / or mold segments 54 would be moved by cams or other suitable means placed around the periphery of the carousel support. In addition, although the female mold section moves in the described embodiment, the description could easily be implemented in a machine in which the male mold section moves, or in which, both of the male and female mold sections are moved. Female mold moves, such as through the cam-driven movement as in the above-noted US Patent No. 6, 706,231. The description is intended to include all modifications and variations that fall within the spirit and broad scope of the appended claims. It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A compression molding machine for plastic closures, characterized in that it comprises: a support that rotates around an axis, a plurality of molds for compression on the support in angularly spaced positions about the axis, each of the molds includes a male mold section and a female mold section, at least one mold section of each mold can be moved with respect to the other mold section between a closed position forming a compression mold cavity and an open position spaced apart from each other, each section of male mold includes a mold core and a spacer sleeve surrounding the mold core for axial, rotational and axial movement of the core, first spindle drive that couples each section of female mold with a corresponding separating sleeve for the rotation of the sleeve The separator is moved around the mold core as at least one mold section is moved between the open and closed positions, and a second screw drive engages each spacer sleeve with the support to move the spacer sleeve in the axial direction over the mold. mold core as the spacer sleeve is rotated about the core, so that each spacer sleeve rotationally and axially removes a molded seal around the associated male mold core according to at least one mold section is moved with respect to the mold core. another to the open position.
2. 2. The machine in accordance with the claim 1, characterized in that each first spindle drive includes a displacement coupling in vacuum that allows the mold sections to be cleared from each other before the rotation of the spacer sleeve around the core.
3. 3. The machine in accordance with the claim 2, characterized because every first drive of. The spindle comprises: a ball screw which includes a ball screw shaft and a ball screw nut, a ball screw drive wheel operatively engaging the ball screw nut with the female mold section, a gear of drive on the ball screw shaft, and the gear teeth on the separator sleeve engaged with the drive gear.
4. 4. The machine in accordance with the claim 3, characterized in that the gear teeth in each spacer sleeve are elongated in the axial direction to allow axial movement of the spacer sleeve with respect to the drive gear.
5. 5. The machine according to claim 3, characterized in that each vacuum displacement coupling is operatively located between the ball screw drive wheel and the female mold section.
6. The machine according to claim 5, characterized in that each vacuum displacement coupling comprises: a support on which the female mold section, a groove in the support, a ball in the groove and a catch receptacle are mounted. in the ball screw drive wheel, the ball is located in the slot in the closed position of the mold sections and moves in the eccentric direction towards the catch receptacle in the ball screw drive as at least one section of mold moves towards the open position.
7. The machine according to claim 2, characterized in that each second spindle drive includes a threaded coupling between the spacer sleeve and the support.
8. 8. The machine in accordance with the claim 1, characterized in that each female mold section is mounted for movement on the support between the open and closed positions.
9. The machine according to claim 1, characterized in that the support is positioned for rotation about a horizontal axis, and wherein the male mold sections and the female mold sections of each mold are aligned along the lengths of the molds. axes perpendicular to the horizontal axis.
10. 10. The machine in accordance with the claim 8, characterized in that the female mold section is radially located outwardly of the male mold section in each of the molds. The machine according to any of the preceding claims, characterized in that it comprises a cam located adjacent to the support to move at least one of the mold sections of each mold with respect to the other mold section between a closed position forming a mold. compression mold cavity and an open position separated from each other. The machine according to claim 11, characterized in that the female mold sections are radially located outwardly of the male mold sections and are movably mounted on the support for movement of the cam between the closed and open positions. with respect to the male mold section.