US2945579A

US2945579A - Plating machine

Info

Publication number: US2945579A
Application number: US573378A
Authority: US
Inventors: Barton James
Original assignee: Frederic B Stevens Inc
Current assignee: Occidental Chemical Corp; Frederic B Stevens Inc
Priority date: 1956-03-23
Filing date: 1956-03-23
Publication date: 1960-07-19
Anticipated expiration: 1977-07-19

Description

July 19, 1960 J. BARTON PLATIN@ MACHINE F'lled March 23, 1956 l0 Sheets-Sheet l i /42 /f/lM /4/ I MI INVENTOR. )mes Zd riz@ 77.

J. BARTON PLATING MACHINE July 19, 1960 10 Sheets-Sheet 2 Filed March 25, 1956 J. BARTON PLATING MACHINE July 19, 1960 Filed Maron 23, i956 10 Sheets-Sheet 3 INVENTOR. 172 7776s 547210 71 J. BARTON PLATING MACHINE July 19, 1960 l0 Sheets-Sheet 4 INVENTOR. 7776s ,54 7'? Filed March 25, 1956 Mff J. BARTON PLATING MACHINE July 19, 1960 l0 Sheets-Sheet 5 Filed March 23, 1956 INVENTOR 7g mes 52472-571 aF/vl/sf J. BARTON PLATING MACHINE July 19, 1960 l0 Sheets-Sheet 6 Filed March 23, 1956 l INVENTOR. UJdWfes rfpn J. BARTON PLATING MACHINE July 19, 1960 Filed March 25, 195e lO Sheets-Sheet 7 July 19, 1960 J. BARTON 2,945,579

PLATING MACHINE .Filed March 25, 1956 10 Sheets-Sheet 8 IN VEN TOR. J a: zes Bya 77 J. BARTON PLATING MACHINE July 19, 1960 I 10 Sheets-Sheet 9 Filed March 25, 1956 '4f/f i -i y Y j B July 19, 1960 J. BARTON 2,945,579

PLATING MACHINE Filed March 23. 1956 l0 Sheets-Sheet 10 United States Patent O PLATING MACHINE James Barton, Detroit, Mich., assignor to Frederic B. Stevens, Inc., Detroit, Mich., a corporation of Michigan Filed Mar. 23, 1956, Ser. No. 573,378

13 Claims. (Cl. 198-19) This application is a continuation-impart of my copending application Serial No. 430,076, filed May 17, 1954, now abandoned.

This invention relates to improved apparatus for lifting and conveying. More specifically it relates to improved automatic apparatus particularly adapted to transport articles through successive stages of elect-roplating, or other processes wherein the article must be lifted and transported from o-ne work station or plating tank to another.

One object of the instant invention is to provide an improved plating machine having work-carrying members mounted for rigidly controlled, smooth vertical travel.

Another object is t-o provide impro-ved electroplating apparatus in which horizontal travel of the work-carrying members is produced -by a force applied to them at points close to their majorsupport points, thus minimizing any tendency of the carriers to skew, or to bind and chatter.

Still another object is to provide an improved electroplating machine including means by which the lifting effort of a plurality of hydraulic cylinders, or other energy sources may be synchronized to produce uniform and even lifting movement along the length of the machine.

These and other objects are accomplished according to the instant invention whi-ch provides an improved plating machine of the so-called return type including a central frame having an elevator mechanism, and `a plurality of individual work carriers, or carriages spaced around the frame and mounted for horizontal movement thereabout. Each of the carriages comprises a slide assembly consisting of a pair of interftted U-channel slides. The respective slides engage each other upon relatively large, at bearing surfaces and are, therefore, rigidly supported with respect to each other regardless of their relative vertical displacement. One of the slides carries a projecting arm, or roller engageable by the elevator mechanism so that it may be selectively raised and lowered.

The carriages are driven horizontally around the machine by a chain driven from a point near the center of the machine.. In this way, the tension on the chain is minimized since the driving force is divided equally between the two ends of the chain.

The invention also contemplates an auxiliary supporting track to bear the weight of the Work carriers When the carriage slides are elevated, and to relieve the lift frame of their Weight. The auxiliary track also provides support at a location closer to the drive chain than is otherwise possible and minimizes any tendency to skew that may occur due to excessive spacing between the drive chain and the point of support of the work carriage.

v Furthermore, the invention provides equalizing means by nection with the accompanying figures of which:`

Y 2,945,579 Patented July 19, 1960 ,ICC c Figure 1 is a diagrammatic, end elevational view of a plating machine according to the invention, illustrating the basic operational principles thereof;

Fig. 2 is a diagrammatic, plan view -of a plating machine according to the invention illustrating its function when used in a plating operation;

Fig. 3 is a side elevational view of the central frame of a plating machine according to the invention from which the Work carriers and certain other parts have been stripped;

Fig. 4 is a cross sectional view of the machine shown diagrammatically in Fig. 1;

Fig. 5 is la longitudinal sectional View of a portion of the machine shown in Fig. 4 taken along the section line 5 5 thereof;

Fig. 6 is a horizontal sectional view of a portion of the machine shown in Fig. l, particularly showing the equalizing mechanism whereby the lifting force applied to the elevator frame by a plurality of hydraulic cylinders is synchronized;

Fig. 7 is a broken, plan view of the lift frame of the machine `as shown in Fig. 3, taken along the line 7--7 thereof, :and particularly showing the mechanism for actuating the lift slides of the frame;

Fig. 8 is a vertical, cross sectional view of the machine as shown in Fig. 3, taken along the section line 8-8 thereof, and showing particularly the actuating means for the lift slide mechanism;

Fig. 9 is a vertical, cross sectional view of the lift slide mechanism shown in Fig. 7 taken along the section line 9-9 thereof;

Fig. 10 isa horizontal sectional View of one of the work carriages indicated schematically in Figs. l and 2;

Fig. 11 is a perspective view of a portion of a machine according to the invention, particularly illustrating a typical roller assembly by which the work carriages are gliliiided around a track upon the main frame of the mac ne;

Fig. 12 isa diagrammatic, vertical, cross sectional view illustrating the lifting mechanism of a machine according to the invention and also the safety, or auxiliary track feature;

Fig. 13 is a side elevational view of the auxiliary track of a plating machine according to the invention;

Fig. 14 is a side elevational view of the horizontal transport drive mechanism of the machine shown in Figs. 1 and 2;

Fig. l5 is la plan view of the drive mechanism shown in Fig. 14; and

Fig. 16 is a schematic circuit diagram showing the electrical control circuits of the machine shown in the preceding figures.

A plating machine according to a preferred embodiment of the invention, and as shown diagrammatically in Figs. 1 and 2, comprises a vertical frame 20 mounted upon a pedestal 22 or any other lconvenient support. Processing tanks 24 are aligned along opposite sides and at the ends of the machine frame. Work-supporting arms 26 are carried around the frame to transport workpieces 27 from one of the tanks 24 to yanother in sequence. The arms 26 are supported on carriages 30 comprising carriage slides 28 slidably mounted in carriage guides Z9. The carriages 30 are mounted for horizontal travel about the frame 2() and are driven intermittently by a chain drive mechanism to be explained in greater detail hereinafter. The carriage slides 28 are mounted for vertical sliding movement within the guides 29 and may be selectively raised `and lowered by a lift frame 34 mounted upon the main frame 20 and actuated by a pair of hydraulic cylinders 50. The timing and control mechanism of the machine is such that horizontal travel of the carriages 30 occurs only when the lift frame 34 is elevated, thus permitting full utilization of the processing tanks since no allowance must be made for horizontal travel of the workpieces 28 while they are within the confines of the processing tanks 24.

The machine will now be described in greater detail starting with reference to the main frame 20 and lift frame 34 assembly, as shown in Fig. 3. The main frame 20 comprises a pair of end columns 40 and a series of intermediate columns 42 all rigidly mounted upon the pedestal 22. The columns 40 and 42 are braced longitudinally by lower and upper

carriage guide rails

44 and 46, respectively, and by a chain guide rail 48, all of which extend substantially along the entire length of the frame, the

carriage guide rails

44 and 46 being continuous and encircling the machine around both ends thereof.

The lift frame 34 is of rigid construction and extends along the length of the machine from one end to the other above the central frame 20. It is supported when in its lowered position by the end columns 40 of the frame. It may be elevated by a pair of hydraulic cylinders 50 mounted upon the pedestal 22 adjacent to the end columns 40. The lift frame 34 is guided in its vertical travel by slides 52 and 54 which form integral parts of the columns 40 and 42, respectively.

The lift frame 34 is maintained level at all times during operation of the machine by an equalizer assembly (shown in greatest detail in Figs. 5 and 6) including a pair of equalizer rods 62 that extend along the length of the machine between the two end columns. The rods 62 are journalled through bearings 66 supported upon cross braces 64 of the columns 40. The rods carry pinions 68, one at each end of each rod, which engage racks 70 rigidly mounted upon the lift frame slides 52. Thus, the vertical travel of the slides l52 at both ends and both sides of the lift frame 34 is coordinated and synchronized by the equalizer bars through the rack and pinion arrangement. Any difference in forces exerted by the two hydraulic cylinders 50 is compensated for by the equalizer assembly, and twisting, or skewing of the lift frame 34 is prevented. If more than two lift cylinders are used to raise the lift frame 34, the equalizer bars may be provided with a sufficient number of pinions to' produce positive synchronization of all the cylinders. A lift frame slide assembly similar to the slides 52 would also be provided adjacent to each of the cylinders to insure smooth vertical travel of the lift frame 34.

As heretofore stated, the carriages 30 are aligned alo'ng both sides of the machine for horizontal movement about the frame 20. They are slidably mounted upon the guide rails 44 and 46 at spaced intervals along the sides of the frame 20. They are movable longitudinally around the frame 20 and are driven by a chain 56 which passes over a pair of end sprockets 58 and is driven by a centrally located drive assembly 60 (Fig. 2). Each of the carriages 30, as best shown in Figs. 4 and l0, comprises outer and inner slide member pairs 72 and 74, and 76 and 78, respectively. The outer members 72 and 74 are rigidly fastened together by braces 80 and 82 to' form a rigid carriage guide 29, the members 72 and 74 being generally of channel shape and facing each other. Each carriage guide 29 is slidably supported upon the

carriage guide rails

44 and 46 for smooth horizontal travel thereon by means of two roller assemblies 84, one roller assembly 84 riding on the upper guide rail 46 and the other roller assembly 84 riding o'n the lower guide rail 44, as shown in Fig. 4. Each of the roller assemblies 84 (Fig. 11) comprises a U-shaped mounting plate firmly secured as by welding or riveting to one of the cross braces 8) of the carriage guide 29. Each roller assembly 84 includes horizontal rollers 88 and vertical rollers 90 all suitably mounted upon shafts and bearings so that the carriage guides 29 are rigidly supported for rolling travel upon the guide rails 44 and 46. i

Referring again to Figs. 4 and l0, the carriage slide 28, comprising the inner pair of

channels

76 and 78, is also rigidly fastened together by cross plates 92 and 94 to keep the

individual channel members

76 and 78 in smooth, sliding engagement with the respective guide channels 72 and 74. A work-supporting arm 26 is mounted upon transverse braces 92 of the carriage slide assembly 28 so that as the carriage slide assembly 28 moves vertically within the carriage guide 29 the worksupporting arm 26 is raised or lowered. A lift roller 96 is mounted upon a cross member 94 near the upper end of the slide assembly 28, and an auxiliary roller 98 is mounted upon one of the cross members 92 adjacent to' the lower end of the slide assembly 28. The auxiliary roller 98 is adapted to cooperate with an auxiliary track 100, the function of which will be explained in greater detail hereinafter. The lift roller 96 is positioned to be engaged by the lift frame 34 for lifting and lo'wering of the carriage slide assembly 28 during operation of the machine. The lengths of the slide 28 and the guide 29 are such that even in its fully raised position the slide 28 is rigidly engaged by the guide 29. It might also be noted here that as shown in Fig. 4, the carriage guide 29 carries a linger, or dog 102 projecting inwardly toward the frame 20, which engages the chain 56 for the horizontal drive.

The lift frame 34 comprises a pair o'f rigid channel members 104 rigidly securedtogether by cross bracing members 106. As shown in detail in Figs. 7, 8 and 9, a discontinuous, weight-supporting angle ange is secured to the outer sides of the channel members 104 to support the carriage slides 2S during their horizontal travel when raised. Gaps 112 are provided in the flange 110 at spaced intervals equal to spacings between the work carriage 30. When the lift frame 34 is raised and lowered, the gaps 112 in the flange 110 permit the flange 110 to pass by the carriage slide rollers 96. Lifting and lowering of the carriage slides 28 is accomplished by

lift plates

116, 118, 12) and 122 mounted in the lift frame 34 and selectively actuatable to engage the carriage slide rollers 96.

Referring now to Fig. 2, in many electroplating and chemical treating operations it is desirable to leave certain workpieces in position in a selected processing tank for several lifting cycles of the machine. No't all of the carriage slides 28 should be raised each time the lift frame 34 is elevated. Some of the tanks, for example, are single station tanks, wherein it is desired to immerse the workpieces for only one dwell period, and to lift them out immediately thereafter. Others of the tanks, on the other hand, extend acro'ss several carriage spaces, and it is desired to leave the workpieces continuously in these tanks for several cycles. The

lift plates

116, 118, and 122 of the lift frame 34 and the gaps 112 in the flange 110 cooperate to provide automatically for the 4different processing times in the various tanks. The lift plates may be adjusted, according to any desired processing sequence, to lift only selected ones of the carriage slides 28 when the lift frame 34 is raised.

The lift plates are of three different structures as shown particularly in Fig. 7. The lift plate 116, for example, is of a single action, double-ended type which may be positioned to till either the left-hand or the right-hand gap 112. The lift plate 118 is a single action, singleended plate which may be advanced into or retracted from a single gap 112 in the flange 110. The third type of lift plate is the double action, double-ended plate 120, 122. This lift plate 120, 122 may be simultaneously advanced into or retracted from both of two opposite gaps 112.

All the

lift plates

116, 118, 120 and 122 are actuated by cams 124 which are driven by a hydraulic cylinder assembly 132 through a shaft 130 by means of a rack 134 and pinion 136, the pinion 136 engaging the rack 134 and being mounted upon and keyed to the shaft 130.

Each of the

lift plates

116, 118, 120 and 122bears a pair of upstanding follower arms 121' that engage the cams 124 for positive advance and retraction of the lift plates by the cams. The hydraulic cylinder 132 actuates the cams to advance or retract the slides according to predetermined settings of the cams 124. These settings are determined by the processing steps desired and the lifting and lowering sequences necessary properly to complete the processing. The hydraulic cylinder is actuated only during times when the lift plates 116-122 are free of weight, i.e., when they do not support the carriage slides 29. The sequence of operation will become apparent hereinafter in the following description of the operation of the machine as a whole.

An auxiliary track 100 completely encircles the central frame 20 of the machine. This track 100 is preferably spaced on the opposite side of the carriages 30 from the frame 20. It cooperates with the lower slide rollers 98 to relieve the weight of the carriage slides 28 from the lift frame 34 during their horizontal travel. It also provides a safety support to prevent lowering of the carriage slides 28 between Work stations in the event of a machine malfunction. The auxiliary track 100 comprises a series of supports 140 and a discontinuous rail 142 shown in elevation in Fig. 13. The rail 142 is formed of a projecting flange member and has gaps 144 spaced along its length at intervals equal to the intervals between the gaps 112 of the lift frame flange 110. The rail 142 includes sloping portions 146 at each side of each of the gaps 144. When the carriage slides 28 are raised, the auxiliary rollers 98 pass through the gaps 144, and when fully raised the lower edges of the rollers 98 are above the edges 147 of the sloping portions 146, but below the main level of the rail 142. When the carriages 30 are advanced horizontally, the rollers 98 roll up the slopes 146 to relieve the lift frame 34 of the Weight of the carriage slides 28. Thus, the support points for the weight of the carriage slides 28 are brought closer to the drive chain 56 to minimize twisting forces onthe carriages 30 during their travel.

Selected ones of the gaps 144 in the auxiliary rail may be closed for skp, or delayed set-down operation by gates 148 pivoted at the far side of the rail from the carriages 30. These gates may be actuated electrically by remotely controlled solenoids 185, or manually by a latch arrangement, as desired. When they are closed, i.e., swung into position to fill the gaps 144, they provide a rest for the auxiliary rollers 98 to maintain the carriage slides 28 in an elevated position and prevent lowering when the lift frame 34 is lowered. Such operation may be desired in order to selectively shorten the length of time the workpieces are immersed in one of the tanks. For example, in a relatively long plating tank hydraulic motor,'which may be located atone end of the frame 20 if convenient. The particular arrangement shown includes a power chain 152 driven by two hydraulic motors 150 through a pair of indexing, over-running clutches 154. The hydraulic motors I150 are `geared to the indexing clutches by gear pairs 156 although, if desired, they may be mounted coaxially therewith for direct drive. The hydraulic motors 150 are of the rotating reciprocating type which may be driveny in either direction through an angle of less than 360. The indexing, over-running clutches 154 are connected by drive shafts to sprockets 160 to drive them in one direction only. When the lift frame 34 is elevated, the hydraulic motors 150 are actuated to move the carriages 30 around the frame 20 a distance corresponding to'the space between any two adjacent carriages, `i.e.,each carriage is advanced one space into the next adjacent work station. The power chain 152 lserves to coordinate and to synchronize the two hydraulic drive motors 150 and to take up any difference in their forces. The power chain 152 carries driving dogs 162 spaced along its length and fitted in alternate links thereof. The driving dogs 162 engage the links of the carriage drive chain 56 to move it along its track 48. 'Ihe drive chain 56 is held in engagement with the driving dogs 162 by the lcarriages 30 which are securely mounted upon the

rails

44 and 46. An inner guide flange 166 is provided to maintain the power chain 152 in its track adjacent to the carriage drive chain 56.

Operation In operation of the machine, and starting with the lift frame 34 and all the carriage slides 28 in their lowerrnost positions, the

lift plates

116, 118, 120 and 122'in the lift frame 34 are positioned by the cams 124 to lift certain selected ones of the carriage slides 28. At v certain stations, such as at single station cleaning tanks, the lift flange 110 on the lift frame 34 is continuous so that the carriage slides 28 at those stations are lifted every time the lift frame 34 is raised. At other locations, such as at the first station in a relatively long tank, there are gaps 112 in the flange 110, closable by lift plates, but open at this stage of the operation. The carriageI slides 28 at these other stations will remain in place and not be raised when the lift frame 34 is elevated. At still other stations, such as at the last station in a relatively long processing tank, the lift plates will be advanced into position in the slides 28 when the lift frame 34 is raised.

it is desired sometimes to process the workpieces during l their full travel time along the tank, and at other times to process them during only a portion of their travel time. In these latter instances the gates 148 corresponding to the first few stations along the length of the tank may be closed so that the workpieces are not lowered at the first station in the tank but at a subsequent station. It will be appreciated, of course, that lift plates in the lift frame 34 must be provided at the station next following the last closed auxiliary track gate 148 so that the carriage slides 28 may be lowered by the lift frame instead of being permitted to fall in an uncontrolled manner when the rollers 98 reach the open gap 144.

yAn illustrative horizontal drive mechanism for the machine is shown in detail in Figs. 14 and 15. This drive mechanism includes two hydraulic motors 150 symmetrically arranged about a central column 42 of the central frame 20. A double drive motor assembly' is particularly desirable in relatively large machines wherein a relatively large number of carriages 30 are moved around the central frame 20. In smaller machines, however, the double assembly may be replaced by a single Fig. 16 shows one illustrative circuit for effectuating automatic control of the machine, and the operation of Ythe machine will be described in connection therewith. `The diagram of Fig. 16 conforms to recently accepted engineering standards, relay solenoids being indicatedby open circles with identifying reference numerals, prefixed R. The separate contacts of the relays are shown as pairs of short, parallel lines, and are related to the respective solenoids by the use of similar reference numerals using Vthe same prefix, R. In cases where one relay solenoid operates several-contacts a hyphenated suflix numeral is used in connection with each different contact. Thus, for example, the solenoid R-4 operates seven different pairs of relay contacts R4-1, R4-2, R4 -3 and so on, up to and including R4-7. A normally closedrelay contact-is indicated by a slant line extending through l'the pair -of parallel lines. An open circle-marked with the letter M indicates an electric motor, or a starter relay for an electric motor. An open circle with `four lines extending radially outwardly from its periphery indicates a lamp such as a signal indicating lamp.k

The circuit vshown includes conventional Start-Stop push button arrangements for separatelyenergizing a hydraulic pump and the circuit itself. The timer 182 starts A the action sequence after the hydraulic pump, the circuit timer 182 initiates the action by energizing the relay R-4. This relay R-4 through its contact R4-4 energizes the hydraulic solenoid valve 184 to raise the lift frame 34, thus lifting selected ones of the carriage slides 28. When the lift frame 34 reaches its uppermost position, it strikes a limit switch S2 to de-energize the solenoid valve 184. The switch S2, when actuated, also energizes the hydraulic motors 150 through a solenoid valve 186 to drive the carriage drive chain 56 to initiate horizontal travel of the carriages 30. At an intermediate position in their travel between stations and after the rollers 96 have rolled off the

lift plates

116, 118, 120 and 122 so that the lift plates are free of load, a switch S14 is tripped by one of the cams 178 carried by the driving dogs 102 of the carriages 30. (The cams 178 may, alternatively, be placed on the drive chain S6 or the power chain S2, if desired.) This switch S-14 actuates the hydraulic cylinder 132 (Fig. 8) through a solenoid valve 188 to change the positions of the

lift plates

116, 118, 120` and 122, retracting those plates that were advanced at the start of the operation and advancing plates that were retracted. The plate shifting action is rapid and is completed before the carriers 30 complete their horizontal travel so that the rollers 96 of elevated carriages do not roll into empty gaps 112 in the lift flange 110.

The completion of horizontal travel of the carriages 30 is signalled by a limit switch S12 tripped by the cams 178. Parenthetically, it may be explained here that the switch S13 is an emergency switch mounted close to the switch S12 and functions through its contact S-13b to stop the entire machine in the event of failure of the switch S12. The switch S11 functions as a bypass for the switch S13 so that the switch S13 does not operate to stop the machine when it is tripped during normal operation.

Referring now to the operating sequence, the switch S12 reverses the hydraulic solenoid valve 186 to stop the hydraulic motors 150 and to retract them to their starting positions. The switch S12 also, through the relay R-3, reverses the hydraulic solenoid valve 184 to lower the lift frame 34. When the lift frame 34 is fully lowered, it strikes a limit switch S1 again to actuate the hydraulic cylinder 132 to shift the

lift plates

116, 118, 120 and 122 back to their starting positions preparatory to the next cycle. The timer is started for the following cycle by the lift frame limit switch S1 through the relay R-S.

In a typical operation, the dwell time, i.e., the time the lift frame 34 remains in its lowered position, may be set at about 9() seconds and the horizontal travel may be accomplished in about to 35 seconds. 1t is, of course, desirable to limit the acceleration during the horizontal travel in order to minimize any swinging motion of the workpieces 27. It is also desirable to control the lowering speed of the lift frame in order to minimize splashing when the workpieces 27 are lowered into liquid-containing tanks.

The circuit as shown in Fig. 16 also includes certain safety limit switch features which are not ordinarily involved in the normal operation of the machine. The main actuating relay solenoid R-4 is, for example, placed in series with safety limit switches S21 and S31 mounted on the lift plate hydraulic cylinder 132 and on the hydraulic drive motors 150, respectively. The switches S2117 and S31b prevent energization of the relay R-4 except when the lift plate hydraulic cylinder 132 and the drive motors 150 are in their normal starting positions. Thus, neither the lifting nor the horizontal drive mechanism can be actuated unless the drive motors 150 are fully retracted and the lift plate hydraulic cylinder 132 is positioned at the full extent of its travel in a desired direction. The limit switches S21a and 822e operate to de-energize the lift plate solenoid valve 188 when the hydraulic cylinder 132 completes its travel in either direction. Any conventional timer may be used in the circuit shown, appropriate connections being made to accommodate the internal construction of the timer. The

particular timer illustrated is one marketed vunder the name Eagle-Microflex and bears the designation, arrangement B-21.

The proper setting of the cams 124 that operate the lift slides 116, 118, 120 and 122 may be best explained with reference to Fig. 2 which illustrates a tank layout for a typical clectroplating process. Several of the tanks are relatively small and comprise only one work station, i.e., the workpieces on only one of the carriers 30 can be immersed in these tanks at any one time. The lift ange may be continuous, without any gaps 112 at these small tanks. Other tanks, however, are relatively long and extend along several adjacent carriages 30. In these long tanks the workpieces may be set down at the first station in the tank and Inot lifted until they reach the last station. The

lift plate

116, 11S, 120 or 122 at the first station in a long tank is retracted after the lift frame 34 is lowered, and is advanced after the lift frame is raised. Thus, the carriage slide 28 at the first station in the tank is not raised by the lift frame 34, but remains lowered and travels horizontally to the second station while the lift frame is elevated. This leaves the first station in the tank empty. While the lift frame 34 is elevated, a raised carriage slide 28 moves onto the advanced lift plate 116, 113, or 122 ready to be lowered into the rst station, now empty, when the lift frame 34 descends.

The reverse situation occurs at the last station in the long tank. After the lift frame 34 is lowered, the lift plate at the last station is advanced so that the carriage slide 28 at that station will be raised when the lift frame 3-2- rises. After the lift frame 34 rises, the raised carriage 3i) moves away from the station and the lift plate is retracted. Simultaneously, another carriage 30 moves into the station, just vacated by the first carriage. This other carriage is in its down position and the lift plate at the station must be retracted to open the gap 112 so that the lift plate will not strike the roller 96 of the carriage when t'ne frame 34 is lowered.

- Full flexibility can be provided in a plating machine according to the invention by providing an aperture 112 at every work station along the lift flange 110, i.e., by providing an aperture 112 corresponding to every one of the carriages 30. Then, by adjusting the lift plate cams 12-4, or by removing the cam follower amis 123, the carriage selection may be adapted to any desired tank layout and processing cycle. lf this type of construction is used, it is, of course, advisable to make all of the lift plates of the double-end, double-throw construction like the lift plates 120 and 122, shown in Fig. 7.

When the machine of the invention is used to convey workpieces through an electrolytic processing sequence, electrical contact may be made to the workpieces by any convenient means. For example, conductive cathode or anode bars may be placed adjacent to the respective processing tanks and positioned to contact the workpieces, or their supporting racks when they are lowered into the tanks by the carriages of the machine.

There has thus been described an improved lift type conveyor machine particularly adapted for use in the electroplating industry. The machine includes means for selectively raising and lowering workpiece carriers and for transporting them horizontally between successively disposed work stations. It also includes improved means to coordinate the lifting force of a plurality of energy sources, and improved means to insure smooth vertical and horizontal travel of the workpiece carriers.

What is claimed is:

1. Apparatus for moving workpieces through a series of treating stations including a central frame, guideway means on said frame defining a closed pathway adjacent to the stations, and a plurality of vertically disposed carriage units mounted for travel on said guideway means around said pathway and outside said central frame, each one of said carriage units comprising a pair of slidably engaged members adapted to telescope one within the other with one such telescoping member vertically fixed to said guideway means and the other such member free to move in a vertical direction, a vertically-movable lifting structure mounted on top of said central frame for vertical travel thereabove, engaging means secured to said vertically movable telescoping member of each of said carriage units in a position to be selectively engaged by said lifting structure, means on said lifting struc-- ture for selectively engaging said lifting means, and means for lifting said lifting structure and said selected telescoping members carried thereby above said central frame.

2. Apparatus for moving workpieces through a series of treating stations including a central' frame having thereon guideway means defining a closed pathway thereabout, a plurality of vertically-disposed work-supporting carriage units mounted `for travel on said guideway means around said pathway, each one of said carriage units cornprising an elongated vertically fixed slideway member mounted for :horizontal travel on said guideway means and an elongated sliding member adapted to telescope with said slideway member, a lifting frame mounted on top of said central frame for vertical travel thereabove and having attached thereto a lift track disposed adjacent to said pathway and having a plurality of openings in the lifting surface thereof, closing means for filling selected ones of said openings in said lifting surface, an engaging member secured to eachone of said sliding members in a position to be engaged by said lift track and said closing means thereon, and means disposed substantially entirely below said lifting frame for lifting said vlifting frame and sliding members c-arried thereby above said central frame.

3. Apparatus for moving workpieces through a series of treating stations including a central frame having thereon guideway means defining a closed pathway adjacent to said stations, a plurality of vertically-disposed workpiece supporting carriages mounted for travel on said guideway means around said pathway, each one of said carriages comprising an elongtaed slidewy member vertically lfixed for travel on said guideway means and an elongated sliding member adapted to telescope with said slideway member, a lifting frame mounted on said central frame for vertical travel thereabove and having attached thereto a lifting track disposed adjacent to said pathway, said lifting track having a plurality of openings in a lifting surface thereof, a lift track-engaging element secured to each one of said sliding members in a position to be engaged by the 4said lifting surface, a plurality of sliding plates mounted on said lifting frame each adapted to enter one of said openings -in said lifting surface, means for advancing and retracting said plates into and out of said openings, and means for lifting said lifting frame and said sliding members carried thereby above said central frame.

4. Conveyor apparatus comprising a frame, a plurality of carriages, means for moving said carriages horizontally yalong'a predetermined path, each one of said carriages including a pair of mutually engaging, vertically telescoping slide members, one of said slide members being vertically fixed, the other one of said slide members being vertically movable through a path disposed above its fully telescoped position, both with respect to said frame, said apparatus also comprising a vertically movable structure disposed adjacent to said path having lifting means thereon selectively movable between an operative and inoperative position, and means to raise and lower said structure, each one of said vertically movable slide members having engaging means to engage said lifting means of said movable structure when in said operative position so that it may be thereby raised partially out of and lowered into the vertically fixed slide member with which it is telescopable.

5. lConveyor apparatus comprising an lelongated central frame, a plurality of `carriages mounted on said frame 10 for smooth horizontal travel along a path completely encircling it, means to propel said carriages intermittently along said path, a lift fname mounted on said central frame for smooth vertical travel above said central frame, and means to raise and lower said lift frame, each one of said carriages comprising a pair of mutually engaging, vertically telescoping slideways, one of said slideways being mounted on said central frame for horizontal travel only, the other one of said slideways being vertically movable through a path disposed above its fully telescoped position, said lift frame -including engaging :means to engage and to raise and lower selected ones of said vertically movable slideways when said lift frame is raised and lowered, said apparatus also including fixed means to support said selected ones of said vertically movable slideways in their raised positions and out of supporting engagement with said engaging means when said carriages are raised and moved horizontally.

6. Conveyor apparatus comprising an elongated central frame, a plurality of carriages mounted on said frame for smooth horizontal travel Ialong a path completely encircling it, a continuous chain engageable by said carriages and encircling said frame, drive means mounted on said frame to drive said chain together with said carriages around said frame, a lift frame substantially coextensive with said central frame and mounted thereon for smoothvertical travel thereabove, means on said central frame to raise and lower said lift fname, aY pair of fixed, rotatable shafts mounted on said central frame parallel to the length thereof, a plurality of spaced pinions coaxially afiixed upon each one of said shafts, a plurality of rack-s secured to opposite sides of and spaced along said li-ft frame, the racks secured to one side of said lift frame engaging different respective ones of the pinions affixed upon one of said shafts, the racks secured to the opposite side of 'said lift frame engaging different respective onesl of the pinions affixed upon the other one of said shafts, each one of said carriages comprising a pair of mutually slid-ably engaging, vertically telescoping slideways, one of said slideways being mounted on said central frame for horizont-a1 travel only,

the other one of said slideways being vertically movable Y through -a path disposed above its fully telescoped position, said vertically mov-able slideways having an engaging member aflixed thereto and disposed -in the vertical path of travel of said lift frame, said lift frame including engaging means to selectively engage said engaging memvbersand to raise and lower selected ones of said -vertically movable slideways when said lift frame is raised and lowered, said apparatus falso including fixed means to support said vertically movable slideways in their raised positions during horizontal travel of said carrrages.

7. In a conveyor apparatus of the type wherein workpieces are moved both horizont-ally and vertically along a predetermined path, the improvement consisting of a carriage comprising a pair of mutually engaging, verticallyY telescoping slides, each one of said slides comprisin g a pair of parallel channel-shaped members yrigidly fastened together in facing, spaced apart relationship, the outer one of said slides being mounted on guide means for horizontal travelponly around said path, the inner one of said slides having support means thereon for supporting workpieces, and being vertically movable upon said outer slide through a path disposed above its fully telescoped position thereon, sai-d inner slide having engaging means connected thereto for engaging lifting means for raising and lowering said inner slides.

8. In conveyor apparatus of the type wherein workpiece supporting carriages `are moved both horizontally a-nd vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member that engages an arm projecting from said carriages, the improvement comprising a fixed supporting rail substantially coextensive with said path, and engaging means mounted on and projecting from said carriages to engage said rail when said carriages are raised and moved horizontally, said vrail being discontinuous and defining spaced apertures through which said engaging means may pass when said carriages are raised and lowered by said lifting member, said rail also including ramp portions sloping upwardly away from said apertures so that when said carriages are raised by said lifting member and moved horizontally said engaging means ride up said ramps still further to raise said carriages.

9. In conveyor apparatus of the type wherein workpiece-supporting carriages are moved 4both horizontally and vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member having an upper lift limit, the improvement comprising a fixed supporting rail adjacent to said path, and engaging means mounted on said carriages to engage said rail when said carriages are raised, said rail being discontinuous and defining spaced apertures through which said engaging means pass during vertical travel of said carriages, said rail also including ramp portions sloping downwardly toward said apertures, said ramp portions being disposed so that their lower ends are below and their upper ends are above the rail-engaging surfaces of said engaging means when said carriages are raised to the upper lift limit of said lift member.

10. In conveyor apparatus of the type wherein Workpiece supporting carriages are moved both horizontally and vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member that engages an arm projecting from said carriages, the improvement comprising a fixed supporting rail substantially coextensive with said path, and engaging means mounted on and projecting from said carriages to engage said rail when said carriages are raised and moved horizontally, means for moving said carriages horizontally, said fixed supporting rail positioned in relative close vertical spacing to said horizontal moving means, said rail being discontinuous and defining spaced apertures through. which said engaging means may pass when said carriages are raised and lowered by said lifting member, said rail also including ramp portions sloping upwardly away from said apertures so that when said carriages are raised by said llifting member and moved holizontally said engaging means ride up said ramps still further to raise said carriages.

11. In conveyor apparatus of the type wherein workpiece-supporting carriages are moved both horizontally and vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member having an upper lift limit, the improvement cornprising a xed supporting rail adjacent to said path, and engaging means mounted on said carriages to engage said rail when said carriages are raised, means for moving said carriages horizontally, said xed supporting rail positioned in relative close vertical spacing to said horizontal moving means, said rail being discontinuous and defining spaced apertures through which said engaging means pass during vertical travel of said carriages, said rail also including ramp portions sloping downwardly toward said apertures, said ramp portions being disposed so that their lower ends are below and their upper ends are above the rail-engaging surfaces of said engaging means when said carriages are raised to the upper lift limit of said lift member.

l2. In conveyor apparatus of the type wherein workpiece supporting carriages are moved both horizontally and vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member that engages an arm projecting from said carriages, the improvement comprising a fixed supporting rail substantially coextensive with said path, and engaging means mounted on and projecting from said carriages to engage said rail when said carriages are raised and moved horizontally, said rail being discontinuous and defining spaced apertures through which said engaging means may pass when said carriages are raised and lowered by said lifting member, closing means associated with said support rail and selectively operable to close selected ones of said spaced apertures maintaining said carriages disposed adjacent thereto in the raised position when said lifting member is lowered, said rail also including ramp portions sloping upwardly away from said apertures so that when said carriages are raised by said lifting member and moved horizontally said engaging means ride up said ramps still further to raise said carriages.

13. In conveyor apparatus of the type wherein workpiece supporting carriages are moved both horizontally and vertically along a predetermined path, vertical movement of said carriages being accomplished by a lifting member having an upper lift limit, the improvement comprising a fixed supporting rail adjacent to said path, and engaging means mounted on said carriages to engage said rail when said carriages are raised, said rail being discontinuous and defining spaced apertures through which said engaging means pass during vertical travel of said carriages, a plurality of gates associated with said support rail each disposed adjacent to one of said spaced apertures, and movable between a closed position in alignment with said rail and an open position, means for moving selected ones of said gates between said positions, said gates when in said closed position disposed to engage said engaging means on said carriages maintaining said carriages in the raised position when said lifting member is lowered, said rail also including ramp portions sloping downwardly toward said apertures, said ramp portions being disposed so that their lower ends are below and their upper ends are above the rail-engaging surfaces of said engaging means when said carriages are raised to the upper lift limit of said lift member.

References Cited in the file of this patent UNITED STATES PATENTS 812,374 Smead Feb. 13, 1906 1,706,905 Stockly Mar. 26, 1929 2,233,055 Kennedy Feb. 25, 1941 2,409,199 Dunlop Oct. 15, 1946 2,461,113 Freidman Feb. 8, 1949 2,609,085 Terhune Sept. 2, 1952 2,639,784 Strock May 26, 1953 2,674,853 Born Apr. 13, 1954 FOREIGN PATENTS 740,127 Great Britain Nov. 9, 1955 UNITED STATES PATENT OFFICE p CERTIFICATE -0F CRRECTION Patent No. 2 945., 579

James Barton It is hereby certified that error appears in the printed specification of the above numbered'patent requiring correction and that the said Letters Patent should readas corrected below.

Column 9, line 39, for .elong'taecv read elongatedl column l2, list of references cited, after line 60 under "UNITED STATES PATENTS" insert following:

Signed and sealed this 31st day of January 1961..

(SEAL) Attest:

KARL H., AXLINE Attesting Officer.-

ROBERT c, -wATs0N Ju1y 19, 19604,

Commissioner of Patents i