US3714925A - Vacuum processing machine - Google Patents

Abstract

A VACUUM PROCESSING MACHINE WHEREIN AN EVACUATED ENCLOSURE HOUSES A SERIES OF INTERMESHING TWO-LOBE ROTORS WHICH ARE ALTERNATELY OSCILLATED A HALF-REGOLUTION TO THEREBY CIRCUMFERENTIALLY SHIFT LENTICULAR CARRIER BOATS RECEIVED WITHIN CONCAVE RECESSES BETWEEN THE LOBES TO A TRANSFER POSITION BETWEEN THE ROTORS. THE LOBES OF THE SUCCEEDING ROTORS SWEEP THE RECESSES TO THEREBY SHIFT THE CARRIER BOATS TO THE NEXT ADVANCED TRANSFER POSITION WHEREBY PARTS NESTED ON THE CARRIER BOASTS ARE BIDIRECTIONALLY SHIFTED ALONG A COMMON ENTRANCE AND EXIT PATH IN A SERIES OF ARCS BETWEEN HANDLING AND PROCESSING STATIONS AT OPPOSITE ENDS OF THE ENCLOSURE.

Description

3,714,925 VACUUM PROCESSING MACHINE Eugene C. Helm, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich. Filed July 30, 1971, Ser. No. 167,566 Int. Cl. C23c 13/10 US. Cl. 11849 1 Claim ABSTRACT OF THE DISCLOSURE A vacuum processing machine wherein an evacuated enclosure houses a series of intermeshing two-lobe rotors which are alternately oscillated a half-revolution to thereby circumferentially shift lenticular carrier boats received within concave recesses between the lobes to a transfer position between the rotors. The lobes of the succeeding rotors sweep the recesses to thereby shift the carrier boats to the next advanced transfer position whereby parts nested on the carrier boats are bidirectionally shifted along a common entrance and exit path in a series of arcs between handling and processing stations at opposite ends of the enclosure.

The present invention relates to a machine for transferring articles and, in particular, to a vacuum processing machine wherein finished and unfinished articles are bidirectionally shifted through a series of controlled environments between handling and processing stations at opposite ends of an evacuated enclosure.

At the present time, large and cumbersome parts such as taillight reflectors pose extremely diflicult problems in subjecting the parts to a high vacuum environment such that a suitable reflective metallic coating can be applied by vapor deposition. Two methods can generally be employed for achieving suitable reflectorizing conditions for these reflectors. In one method, a single reflector is placed in a chambered fixture which is evacuated until the desired vacuum is reached at which time the reflective coating is applied. Thereafter, the chamber is repressurized and the reflector removed. However, the separate pump down time required for each article greatly limits the production rate, particularly inasmuch as the pump down time considerably exceeds the coating time. In the other method, a partial reduction in the pump down time versus the coating time is achieved by positioning multiple reflectors within a single evacuating chamber and, when the desired vacuum is reached, sequentially or simultaneously applying a reflective coating to the articles. This also is not entirely satisfactory inasmuch as the large volume chamber requires a substantial pump down time which again limits the production rate.

The present invention contemplates a continuous vac uum processing machine for applying a coating to an article wherein the reflectorizing process proceeds substantially independently of the system pump down time. Basically, this improved performance is achieved by continuously routing unfinished parts sequentially through a series of controlled environment chambers to a high vacuum processing station for application of the coating. Thereafter, the reflectors are reversely routed along the same path for exit at the handling or entrance end of the machine. The individual chambers are independently sealed and have progressively increasing vacuums toward the processing station. This provides a vacuum environment at the processing station which can be continuously maintained and is relatively unaffected by the transferring of parts.

The parts are routed through the machine by a transferring mechanism including a series of intermeshing twolobe rotors which operatively cooperate with adjacent rotors and the enclosure to shift articles toward and away United States Patent pp 3,714,925 Ice Patented Feb. 6, 1973 from the processing station. Each rotor includes diametrically opposed cylindrical lobes which are circumferentially spaced by concave cylindrical recesses. The rotors are spaced on shortened centers and, when the lobes of one rotor are perpendicular to the center line of the machine, the other rotor is freely rotatable and sweeps the cylindrical recesses. The articles are mounted on lenticular carrier boats having one cylindrical surface positioned within the recess and the other cylindrical surface forming a continuation of the lobes. Cam drive means are provided for alternately oscillating alternate rotors or one-half revolution. In this manner, the carrier boat is circumferentially shifted along an arcuate path by the first rotor for a half revolution and stopped at a holding position between the rotors. Thereupon, the second set of rotors is rotated and the lobes thereof sweep the carrier boats from the first holding positions to second holding positions between the next adjacent rotors. At the other end of the machine during the dwelling period of the end rotor, a reflective coating is applied to the article. During the reverse rotation of the end rotor, the finished article is reversely shifted to the last holding position along its entrance path. Simultaneously, an unfinished article is shifted from the last holding position to the processing station along a diametrically opposite or parallel path. Thus, parts are alternately fed into the machine and bidirectionally carried through a series of controlled environments in parallel paths for handling and processing at opposite ends of the machine.

These and other features of the present invention will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings showing a preferred embodiment in which:

FIG. 1 is a side cross sectional view of a vacuum processing machine made in accordance of the present invention;

FIG. 2 is a view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged view taken along line 33 of FIG. 1;

FIG. 4 is an enlarged perspective view of the carrier boat and the rotor;

FIG. 5 is an enlarged fragmentary view of the processing station; and

FIG. *6 is a process flow schematic for the vacuum processing machine.

Referring to FIGS. 1 and 2, there is shown a vacuum processing machine 10 for applying a reflective coating to articles such as taillight reflectors 11. The machine 10 generally comprises a vacuum enclosure 12 supported on legs 14 and having an open entrance or handling station 16 at one end and an enclosed processing station 18 at the other end. The enclosure 12 includes a top wall 20, a bottom wall 22, a pair of spaced side walls 24, and an end wall 26. A series of four intermeshing two- lobe rotors 30, 32, 34, 36 are rotatably carried within the enclosure 12. The side walls 24 and the end wall 26 include interior concave surfaces conforming to the outer surfaces of the aforementioned rotors.

The rotors 30, 32, 34, 36 respectively include drive shafts 40, 42, 44, 46 which are journalled in and project downwardly through openings in the bottom wall 22. Each drive shaft 40, 42, 44, 46 carries a spur gear 50, 52, 54, 56 respectively. Cam drive means 60 are provided for alternately oscillating alternate rotors in a manner described below.

Referring to FIG. 4, the representative rotor 30 comprises planar top and bottom surfaces 61, a pair of diametrically opposed lobes 62 having right circular peripheral surfaces 63, and a pair of diametrically opposed concave circular recesses 64 formed normal to the lobes 62.

A sealing strip 68 disposed in a groove around the surfaces 61 and 63 cooperates with the wall of the enclosure to a seal between adjacent rotors. As shown in FIG. 2, the rotors are mounted on shortened centers D at a distance equal to the radius of a lobe 62 plus the radius to the base of the recess 64. With the lobes 62 perpendicular to a longitudinal axis 70 through the centers of the rotors, each recess 64 forms a circular continuation of the peripheral surface 63 of an adjacent rotor. Additionally, the mutually facing recesses between successive rotors will establish three holding chambers 72, 74, 76. At the processing station 18, the rotor 36 and the end wall 26 form a processing cavity 78. Therefore, when one set of rotors are located with the lobes perpendicular to the longitudinal axis 70, the adjacent rotors are freely rotatable with the lobes thereof sweeping the aforementioned recess 64 and chambers.

Controlled vacuum environments are maintained between adjacent sealing strips 68 in the chambers 72, 74, 76, 78 by vacuum pumps 80, 82, 84, 86 which are respectively connected thereto. The pumps have a capacity to maintain the chambers at progressively increasing vacuums which is a minimum of around .1 micron in the processing chamber 78. During oscillation of the rotors, adjacent pumps jointly evacuate the transient space between alternate sealing strips 68 thereby minimizing the effects of the transferring operation on the prevailing environment.

The reflectors 11 are mounted on lenticular carrier boats 90 defined by opposed convex surfaces 92 having a radii equal to the radii of the lobes 62. Accordingly, when the carrier boat 90 is received within a recess 64, one convex surface 92 engages the inner periphery thereof and the other convex surface forms a circular continuation of the lobes 62.

The carrier boats 90 are bidirectionally shifted through the enclosure 12 by the rotors as controlled by the drive means 60 which includes racks 100, 102, a pair of cams 104, 106, and a drive train including an electric motor 108 operatively coupled to a gear reduction unit 110. The cams 104, 106 are rotatably mounted on an output shaft 111 connected to the gear reduction unit 110. Referring to FIG. 3, the representative rack 100 is provided with gear teeth which mesh with the spur gears 52 and 54, of rotors 30 and 32. In a similar manner, the rack 102 meshes with the spur gears 52, 56 of rotors 32, 36. Cam follower pins 112 connected at the ends of the racks 100, 102 operatively engage the cam surface 114 of the cams 104, 106.

The profile of each cam includes 90 segments comprising in clockwise circumferential order a dwell sector A (alpha), a rise sector B (beta), a dwell sector I (gamma), and a fall sector A (delta). The cams 104, 106 are circumferentially spaced 90 apart such that one cam is operating on a dwell sector while the other cam operates on an actuating sector. In this manner, the cams serve to alternately reciprocate the rack gears 100, 102 so as to alternately oscillate their respective rotors with intermediate rest periods.

The processing station 18 is provided with an aluminizer 120 which is mounted on the bottom plate 22 and registers with the cavity 78 through an aperture 122. The aluminizer 120 includes a crucible 124 which is resistance heated to vaporize aluminum for deposition upwardly through an opening 126 in the carrier boat 90 onto the interior surface of reflector 11. The aluminizer is conventional in construction and is appropriately energized during each dwell sector A and I of the end rotor 36.

Referring to FIGS. 2 and 6, in operation unfinished refiectors are shifted along a series of semi-circular paths toward the processing station 18 while finished reflectors carried by the same rotor are reversely shifted along a parallel path toward the handling station 16. However, with regard to an individual reflector, the identical path is used for ingress and egress. Thus, unfinished and finished parts are transferred through a series of controlled environments for entrance and exit of one end of the machine and for aluminizing at the other end.

More particularly, upon machine start up, a first or odd numbered carrier boat is positioned within a recess 64 of the entrance rotor 30. During the rise sector B, the cam 104 drives the rack to the left thereby rotating rotor 30 one-half revoltion or 180 in the counterclockwise direction. The intermediate positions of the rotor 30 and 34 is shown by phantom lines in FIG. 2. At the same time, the cam '106 is traversing the dwelll sector A and the intermediate rotor 32 remains stationary. Accordingly, as shown in FIG. 6, the carrier boat 90 is carried on a semi-circular path from the handling station 16 to the first holding chamber 72 along a semi-circular circumferential path 130. When the first carrier boat reaches the holding cavity 72, the entrance rotor 30 is locked in place as the cam 104 traverses the dwell sector I. Simultaneously therewith, lthe dam 106 traverses a rise sect-or B thereby shifting the rack 102 to the left and oscillating the intermediate rotor 32 one-half revolution in a counterclockwise direction. This movement shifts the first carrier boat in a semi-circular path 132 to the second holding chamber 74.

During the dwell sector I of the rotor 30, a second or even numbered carrier boat is positioned within the recess 64. As the cam 104 traverses the fall sector A (delta), the rack 100 is shifted to the right and the rotor 30 carries the second part, as shown by the dotted lines, in a clockwise direction along a path 134 for deposit at the holding cavity 72 while the intermediate rotor 34 transfers the first carrier boat to the holding chamber 76 along a path 136.

During the next 90 sector, the rotors 32 and 36 are driven in a clockwise direction by the fall sector A of the cam 106 and the first and second carrier boats are transferred to the processing chamber 78 and the second holding chamber 74 along paths 138 and 140, respectively.

During the next dwell periods of the rotor 30, 34, the second carrier boat and third carrier boat are transferred to the chambers 76 and 72 along paths 142, 130 respectively while the aluminizer is energized for applying a coating to the reflector 11 on the first carrier boat. The second carrier boat is subsequently transferred to the processing station 18 along path 144 for aluminizing while the finished odd number reflector is transferred to the chamber 76 along the path 138.

Regarding unfinished parts, during the next complete revolution the earn 104, the first and odd number carrier boats will exit the machine along their entrant path 130, 132, 136 and 138. Similarly, the second and even numbered reflectors will follow an exiting path identical to their entrant path 136, 140, 142, 144.

Accordingly, it will be noted that the odd numbered carrier boats will follow identical paths as they are bidirectionally routed between the handling station 16 and the processing station -18. The even numbered carrier boats will move along a path which is parallel to the mirror image of the first path. Thus, for each oscillation of the rotors, an unfinished part advances forwardly while a finished part retreats. In this manner, reflectors proceed through the machine on a continuous basis without being dependent on the pump down time of the machine. Accordingly, the production rate for the machine will be substantially solely governed by the aluminizing time at the processing station.

Although only one form of this invention has been shown and described, other forms will be readily apparent to those skilled in the art. Therefore, it is not intended to limit the scope of this invention by the embodiment selected for the purpose of this disclosure but only by the claim which follows.

What is claimed is:

1. A vacuum processing machine for applying a coating to an article, comprising: an enclosure having a handling station at one end and a procesisng station at the other end; means for maintaining controlled environments at spaced locations along said enclosure; two sets of alternately spaced two-lobe rotors rotatably mounted within said enclosure for oscillation between a first transfer position and a second transfer position, said rotors having alternating circular lobes and concave recesses and being spaced on shortened centers such that the lobes of one rotor mesh with and sweep the recess of an adjacent rotor intermediate said transfer positions; sealing means between the rotors and the enclosure for maintaining said controlled environments; means at said processing station for applying a coating to articles positioned therein; lenticular carrier boats receivable within said recesses having a first circular surface conforming to said recesses and a second circular surface forming a continuation of said lobes; first cam drive means for oscillating one set of rotors one-half revolution to thereby advance carrier boats carrying unfinished articles in a semi-circular path between successive transfer positions toward the processing station and return carrier boats carrying finished articles in a parallel semi-circular path toward the handling station; and second cam drive means for oscillating the other References Cited UNITED STATES PATENTS 1,774,529 9/1930 Sharp 99-272 2,516,908 8/ 1950 Pottle 118-50 2,730,068 1/1956 Reynolds et al. 118-49 3,037,607 6/1962 Hi-ghfield et a1 198-19 3,656,454 4/ 1972 Schrader 118-49 MORRIS KAPLAN, Primary Examiner US. Cl. X.R. 198-19

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