US3266502A - Chemical milling machine - Google Patents

Description

Aug. 16, 1966 w. E. COPELAND CHEMICAL MILLING MACHINE 7 Sheets-Sheet 1 Filed Sept. 14, 1964 d a Z \\MP. 0 1 m 4 V 2% W 3\ 0 e Mu; i 2? W M Q .l ,6

J Z a a w ,5, M e, 4 s k M a MHZ I I I I ll r e WW 6, 1966 w. E. COPELAND 3,266,502

CHEMICAL MILLING MACHINE Filed Sept. 14, 1964 7 Sheets-Sheet 2 Aug. 16', 1966 w. E. COPELAND CHEMICAL MILLING MACHINE '7' Sheets-Sheet 5 Filed Sept. 14, 1964 L g I I Aug. 16, 1966 w. E. COPELAND CHEMICAL MILLING MACHINE 7 Sheets-Sheet 4 Filed Sept. 14, 1964 Aug. 16, 1966 w. E. COPELAND 3,266,502

CHEMICAL MILLING MACHINE Filed Sept. 14, 1964 7 Sheets-Sheet 5 Ila/0r "134 Aug. 16, 1966 w. E. COPELAND CHEMICAL MILLING MACHINE Filed Sept. 14, 1964 3,266,502 Ice Patented August 16, 1966 3,266,502 CHEMICAL MILLING MACHINE Wayne E. Copeland, Los Angeles, Calif., assignor to Western Technology, Inc, Burbank, Calif., a corporation of California Filed Sept. 14, 1964, Ser. No. 396,022 9 Claims. (Cl. 134-57) The present invention relates to an improved etching and chemical milling machine which is fully automatic in its operation.

The improved machine of the present invention finds general utility in the chemical milling field. Chemical milling is a process whereby certain areas of a material, such as stainless steel, aluminum or magnesium, are milled out by chemical etching. The etching is achieved by masking the areas which are not to be etched by a fihn of a resist material. This film, for example, may be applied by photographic techniques, as is Well known to the art. The unmasked areas of'the workpiece are exposed to the action of a suitable etching In the operation of the improved machine of the present invention, the etchant is directed as finely atomized, high pressure sprays against one or both sides of a masked workpiece. The high pressure sprays provide for both mechanical and chemical erosion of the exposed areas from the workpiece. This mechanical erosion, in addition to the usual chemical erosion, serves to decrease the undercut effect to a minimum, and to increase the speed at which the workpiece is treated.

After the workpiece has been etched to a desired degree, it is removed from the etching chamber of the machine and placed in a rinse chamber. The workpiece is thoroughly rinsed in the rinse chamber to stop the etching action and to remove all traces of the etchant.

Difiiculties have been encountered in the past in accurately controlling the depth of the etching process and of holding the under-cut effect to a minimum. Dilficulties have also been encountered in the prior art machines of maintaining uniformity in mass production. These difliculties are overcome in the machine of the present invention, inter alia, by the use of the aforesaid mechanical erosion system, and by holding the temperature and other parameters precisely constant during the etching process.

An object of the present invention is to provide an improved etching and chemical milling machine which 18 constructed to treat workpieces with a greater degree of uniformity and at higher speeds than has heretofore been possible.

A further object of the invention is to provide such an improved machine which is fully automatic yet functionally simple; and which is safe, reliable and easy to operate.

A still further object of the invention is to provide such an improved machine which operates on a principle of a closed and sealed system so as to obviate any tendency for the etchant to contaminate the surrounding environment, and to eliminate the escape of contaminating fumes, or the like. Thus, the machine of the present invention provides a completely safe, closed system. The operator need not wear any special clothing or a mask. In addition, no venting is required for the etching room or facilit A more specific object of the invention is to provide a fully automatic, push button, high speed chemical etching and milling machine for fine line foil etching, or deep etching of other material; and which is capable of precision duplication of successive workpieces, with even etch, no teardropping, no puddling of the etchant, and minimum under-cutting, for the mass quantity of identical workpieces.

production of any The machine of the particular embodiment of the invention to be described is constructed for two-sided etching, milling and rinsing of the workpiece. When the processing of only one side of the workpiece is desired,

the operator merely pushes a manifold selector button corresponding to the particular side of the workpiece, top or bottom, which is to be processed.

An important feature of the equipment to be described is the use of high etchant pressure, of the order of pounds per square inch at the nozzles, for example; and also the use of closely spaced nozzles having of the order, for example, of 2' centers. This results in a complete and continuous coverage of the surface of workpiece for the desired mechanical and chemical erosion. The mechanical action of the sprays continuously removes oxide films, and the like, from the workpiece surface, so that a clean surface is presented to the sprays at all times and the chemical etching action is thereby not impeded throughout the entire etching action.

At the beginning of the operation, the workpiece is first placed on a pallet in the rinse chamber and the machine is activated by appropriate push-button controls, as mentioned above. After the temperature, pressure and timing controls of the machine are preset, it will proceed automatically through the etching and rinsing cycles. When the machine has completed the cycles, it shuts off automatically. Any cycle may be interrupted at the operators option.

The pallet and workpiece are moved manually to the etching chamber, before the machine is activated. Then the rinse chamber is closed and the machine is activated. The etchant sprays are then automatically turned on, and after a precisely timed interval they are automatically turned off. The pallet and workpiece are then returned automatically to the rinse chamber.

The spray nozzles in the rinse chamber are then automatically activated, so that the workpiece may be sprayed with water to stop the etching process and to rinse off all excess etchant. The rinse spray nozzles are subsequently automatically turned oil, and the workpiece may be removed by opening the rinse chamber.

The etching chamber of the machine to be described includes an electrically energized heating coil and a tubular cooling coil. The flow of electricity through the heating coil, and the flow of coolant (such as water) through the cooling coil are thermostatically controlled. This permits a precise control of the temperature in the etching chamber to be established at any temperature level and to within, for example, plus or minus 1 Fahrenheit.

The cooling coil may be composed, for example, of titanium, and the heating coil may be sheathed by titanium, so as to preclude attack by the etchant.

The machine to be described herein utilizes, as mentioned above, mechanical erosion of high pressure hard sprays of the etchant, in addition to the usual chemical erosion eifectuated thereby. This mechanical erosion results in new dimensions in deep etching and chemical milling. A high volume of etchant is moved against the workpiece in the etching chamber through specially constructed nozzles in highly atomized form and under high pressure. The result is an improvement of the undercut factor by the order of 3:1, for example, as compared with the usual prior art systems and mechanisms.

In order to prevent the occurrence of hot spots and cold spots at the surface of the workpiece as it is sprayed with the etchant, the etchant nozzles are mounted on movable manifolds, as indicated above. The workpiece is held horizontally, and the manifolds are positioned in horizontal planes over and under the workpiece in the embodiment to be described. The manifolds are both moved reciprocally in the X- and Y-axes direction in their respective planes. In this manner, extremely even distribution of the etchant sprays over the workpiece is assured. The horizontally disposed workpiece also assures safe etching of fragile parts.

Thus, there is no differential drainage of the etchant, as in the usual prior art machines, in which the workpiece is held vertically. The top and bottom manifolds with the spray heads, or nozzles, are moved uniformly. As mentioned above, sheer mechanical force of the high pressure etchant sprays from the nozzles drives the etchant against the exposed parts of the workpiece surface, and displaces the spent etchant and eroded material. This results in extremely clean and rapid penetration.

A pair of independently controlled high volume centrifugal pumps are used to pump the etchant from the etchant tank to the aforesaid respective upper and lower manifolds. These pumps, for example, may be of the type described in copending application Serial No. 434,- 450 filed February 23, 1965 and entitled Pump, and they serve to provide the required high etchant pressure at the spray nozzle.

A separate load/ unload pump is used to load the etchant into the etchant reservoir tank. This latter pump may, for example, have a capacity of gallons per minute. The load/unload pump can also be used to circulate the etchant in the reservoir so as to permit a sample to be taken in order to check Baum, for example. This load/unload pump can also be used when the etchant reservoir tank is being flushed out.

The aforesaid spray nozzles are mounted on the manifolds in the etchant chamber, in a manner such that each nozzle presents a relatively long column to the corresponding manifold. This enables air initially in the column to absorb the first shock of etchant when the spray system is activated. This action prevents the water hammer effects, and obviates any danger of the nozzles to be driven out of the manifold even though relatively high etchant pressures are established. The nozzles may be composed, for example, of polypropylene.

In the embodiment to be described, the pallet and the workpiece are moved automatically from the etching chamber to the rinse chamber by a special hydraulic system, at the completion of the etching process. This precludes the need for switches, gears, motors, electrical power, and it provides positive reliability.

A rocking mechanism is also coupled to the pallet when it is in the etching chamber. This mechanism causes the pallet to rock during the etching process, so as to eliminate any puddling of the etching on the workpiece. It is apparent that any such puddling would militate against effective mechanical erosion by the high pressure sprays.

The rinse chamber, for example, contains a multiplicity of precision spray heads, as mentioned above. Instant rinsing of the workpiece halts the etching action, and it prevents etchant contamination of the workpiece. After the complete rinse cycle, the machine shuts off automatically.

The features of the invention which are believed to be new are set forth with particularity in the claims. The invention itself, however, together with further objects and advantages thereof, may best be understood by reference to the following description, when the description is taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a front perspective view of a machine constructed in accordance with one embodiment of the invention;

FIGURE 2 is a schematic representation of a pumping system incorporated in the machine of FIGURE 1, whereby pressurized etchant is provided for the spray nozzles of a pair of manifolds in the etching chamber;

FIGURE 2a is an exploded, perspective view of one of the spray nozzles;

FIGURE 3 is a sectional view of the machine of FIG URE 1 taken substantially on the line 33 of FIGURE 1;

FIGURE 4 is a fragmentary perspective view of a por- 4 tion of the machine of FIGURE 1, and showing the manner in which one of the aforesaid manifolds is mounted in the etching chamber of the machine for reciprocal motion in two directions in a particular plane;

FIGURE 5 is a fragmentary view showing the manner in which the second manifold is mounted in the etching chamber of the machine for reciprocal movement along two axes in a particular plane;

FIGURE 6 is a perspective view of a Teflon button, a plurality of which is used as a sliding means for the aforesaid manifolds;

FIGURE 7 is a view, substantially along the line of 7-7 of FIGURE 4, and showing an actuator shaft which is used in the control of the reciprocal movement of the aforesaid manifolds;

FIGURE 8 is an end view of the machine of FIGURE 1, taken substantially'on the line 88 of FIGURES 1 and 3, and showing a control compartment which houses actuator assemblies'for driving the aforesaid manifolds, and which also houses other electrical components (not shown);

FIGURE 9 is a sectional view, on an enlarged scale, of one of the actuators shown in FIGURE 8;

FIGURE 10 is a top plan view illustrating one of the aforesaid manifolds;

FIGURE 11 is an exploded perspective representation of the construction of the nozzles used in a particular embodiment of the invention in conjunction with the aforesaid manifold for producing the desired high pressured sprays of the etchant;

FIGURE 12 illustrates the system used in the machine of FIGURE 1 for maintaining the etchant solution in the reservoir tank of the machine at a predetermined temperature;

FIGURE 13 is a perspective fragmentary representation of the hydraulic system used in the machine of FIG- URE 1 for moving the pallet in the machine from the etching chamber to the rinse chamber automatically;

FIGURE 14 is a perspective fragmentary View of a rocking mechanism included in the etching chamber;

FIGURE 15 is another fragmentary view of the rocking mechanism; and

FIGURE 16 is an electrical circuit diagram of the various electrical controls used in the machine.

As mentioned above, the improved machine of the present invention provides a fully automatic means for chemically milling or etching a workpiece. The machine as described previously herein, is fully enclosed and sealed, so that no fumes issue from the machine.

As shown in FIGURE 1, the improved machine includes a housing 10. The housing may be constructed, for example, of a multiply, plyboard panel construction, for example, of finish birch. Each panel is completely clad by, for example, polyvinyl chloride, so as to render the panels moisture-tight and to render the housing impervious to attack from the etchant. The various seams and lead troughs are welded with a polyvinyl chloride welding rod. The resulting construction provides a housing which is relatively light and relatively inexpensive; and yet which is rugged and durable, and completely immune to attack by the etchant.

The housing 10 defines several compartments within the machine. The first compartment, designated 12, is a load and unload compartment, and it also serves as a rinse chamber.

The compartment 12 has a cover 14 hinged to it, the cover having a glass front 16, for example, for viewing purposes. The cover 14 may be moved to the open posi tlon shown in FIGURE 1; or a closed position during wlhich rinsing operation in the compartment 12 may take p ace.

A first rinsing manifold 18 is positioned in the bottom of the compartment 12, and a second rinsing manifold is mounted 1n the cover 14. Water, or other appropriate rinsing fluid, is supplied under pressure to the manifolds 18 and 20 under a suitable control, as will be described, so that rinsing sprays may issue from a multiplicity of nozzles 22 and 24 which are mounted on the respective manifolds.

The housing 10 also defines an etching chamber 26 which is completely enclosed, and which may, for example, have a transparent panel 28 in one side for viewing purposes. A pallet 30 is mounted on appropriate slides 32, so that it can be moved between the rinse compartment 12 and the etching chamber 26. At the beginning of the operation, the workpiece is placed on the pallet in the rinse chamber, and the pallet and workpiece are then pushed manually into the etching chamber.

As will be described, water pressure is used in a hydraulic system to move the pallet automatically from the etching chamber 26 out into the rinse chamber 12 at the termination of an etching operation.

The housing 10 also defines an etchant storage reservoir tank 34 under the etching chamber 26. A load/unload pump 36 is used to pump the etchant solution from an appropriate portable container into the etchant reservoir tank, Whenever additional etchant is required. As mentioned above, the pump 36 may also be used to circulate the etchant in thev storage tank, so that accurate Baume readings may be taken. In addition, the pump 36 also aids in flushing out the reservoir tank 34; at which time the pump is reversed, and it pumps the fluid through an appropriate external line into the rinse chamber 12, from which its discharge is drained into the city drainage.

A pair of movable manifolds 38 and are mounted in the etching chamber 26. It will be appreciated that each of the manifolds 38 and 40 is positioned in a horizontal plane, and these planes are spaced and parallel from one another. Likewise, the pallet 30 is moved in a horizontal plane, and when the pallet 30 is in position in the etching chamber 26, it holds the workpiece horizontally between the manifolds 38 and 40 and in a spaced parallel relationship therewith.

The manifolds 38 and 40 each contain a plurality of high pressure nozzles, as will be described, composed, for example, of polypropylene; and these nozzles provide high pressure sprays of the etchant from the storage tank 34 for mechanical and chemical erosion purposes, as described above.

The etchant is pumped from the reservoir 34 to the upper manifold 38 by means, for example, of a pump 42. Likewise, the etchant is pumped from the reservoir 34 to the lower manifold 40 by means of a pump 44. The pumps 42 and 44 may be constructed, for example, in the manner described and claimed in copending application Serial No. 434,450.

Thus, individually controlled, high efiiciency centrifugal pumps 42 and 44 supply the upper and lower spray nozzle manifolds in the etching chamber with a high volume of pressurized etchant. In addition, the manifolds are equipped with especially constructed and specially mount- 7 ed spray head nozzles to accept the high pressurized etchant so as to yield finely atomized hard etchant sprays.

The mechanism of FIGURE 1 also includes a control panel 46. This panel incorporates appropriate controls, so that the machine may be put through its cycle.

In the operation of the machine, and assuming that the etchant reservoir 34 has initially been filled with a suitable etchant solution by means of the load/unload pump 36, the cover 14 of the rinse chamber 12 is opened and the workpiece to be treated by the machine is placed on the pallet 30. The pallet is then pushed manually into the etching chamber 26, and the cover 14 is closed.

One, -or both, of the pumps 42 and 44 are now activated. This activation of the pumps causes the nozzles associated with the manifolds 38 and 40 to issue high pressure sprays of the etchant material on one or both sides of the workpiece, as desired. It will be appreciated, as mentioned above, that either one of the pumps 42 and 44 can be activated singly, so as to provide high pressure sprays from either the top manifold 38 or bottom manifold 40.

While the sprays are issuing from the manifolds 38 and 40, these manifolds are moved reciprocally in their respective planes at predetermined rates and in the X-Y direc tion, so as to avoid any danger of the production of hot spots or cold spots. In a constructed embodiment of the invention, both manifolds are reciprocally moved in the Y direction by a common actuator and at a rate of 5 r.p.m. of the actuator drive motor; whereas the manifolds are driven reciprocally in the Y direction by individual actuators, and at a rate of 25 r.p.m. of the actuator drive motors.

After a predetermined time has elapsed, the pumps 42 and 44 are automatically deactivated, and the pal-let 30 is automatically returned to the rinse chamber 12 by means of a hydraulic system, as will be described. The rinsing sprays in the rinse chamber 12 then are caused to issue from the nozzles 22 and 24, so that the workpiece may be thoroughly rinsed. The cover 14 may then be opened, and the workpiece removed.

The etchant spray system is shown schematically in FIGURE 2. As shown in FIGURE 2, a pair of disposable filters 50- and 52 are provided in the etchant reservoir tank 3 4 at the suction side of each of the pumps. The resulting self-contained etchant filtering system protects the nozzles and pumps from contamination. The constructed embodiment of the invention utilizes two molded, 300 micron, polyethylene filters. These filters are easily removable for back flushing and replacement purposes. This filtration system prolongs the life of the machine, and minimizes time loss in maintenance.

As shown clearly in FIGURE 2, when either or both of the pumps 42 and 44 are activated, the etchant solution is drawn through the filters 50 and 52 from the etchant reservoir 34 and supplied under pressure, through corresponding pipelines 54 and 56, to the upper and lower manifolds 38 and 40, respectively. A portion of each of the pipelines 54 and S6 is flexible, as will be explained in conjunction with FIGURES 3, 4 and 5, so as to permit the desired reciprocal movement of the manifolds.

As shown in FIGURES 3 and 4, for example, the pipeline 54 is coupled to a flexible tube 54A which, in turn, is coupled to a fitting 60 on the manifold 38 (FIGURES 3 and 4). The pressurized etchant in the pipe line 54 is fed through the flexible coupling 54a to the interior of the manifold through the fitting 60. Likewise, the pipe line 56 is coupled to a similar flexible tube "56a (FIGURE 5) which, in turn, is coupled to the interior of the lower manifold 40.

The upper manifold 38 is mounted on a pair of rods, such as the rod 62 (FIGURE 4), and these rods extend transversely across the etching chamber 26. The manifold 38 is supported on the rod 62 by respective angle end pieces, such as the piece 64, for sliding motion on the rod 62 back and forth across the etching chamber 26 on appropriate buttons 66, composed, for example, of Teflon (see also FIGURE 6).

A pair of rods 68 extend longitudinally in the etching chamber between the two transverse rods 62. The manifold 38 also includes a pair of angle side members 70 and 72 which slide on the rod 68, likewise on Teflon buttons 66, for example.

The manifold 38 is hung on the angle side members 70 and 72 by means of L-shaped brackets 74, which are welded to the adjacent side members 70 and 72.

By means of the construction described above, and as shown in FIGURES 3 and 4, the manifold 38 itself is capable of movement in its plane in an X direction, for example, sliding along the rods 68; and the manifold is capable of movement in a Y direction, for example, sliding along the rods, such as the rod 62.

The movement of the manifold 38 in the aforesaid X direction is controlled by an actuator rod 78 which extends into a control compartment (FIGURES 3 and 8).

The actuator rod 78 is moved reciprocally by means of an actuating mechanism 82. The actuator rod 78 is coupled to a bracket 86 on the manifold 38 by means of a pivotally mounted connecting arm 88. As the actuating rod is moved back and forth by the actuator mechanism 82, the upper manifold 38 is moved reciprocally in its plane in the X direction.

A second actuator rod 98 extends from an actuator mechanism 92 in the control compartment 80 into the etching compartment 2 6. This latter actuating rod is coupled by a connecting rod 94 to a radial arm 96 which is mounted on a vertical shaft 98 (FIGURE 7). The shaft is mounted in the etching compartment 26 between two mounting brackets 99 (FIGURE 7).

As the actuating rod 90 is moved back and forth by the actuating mechanism 92, the connecting rod 9'4 causes the vertical shaft 98 to move angularly in a reciprocal manner. A further crank arm 100 is mounted on the shaft 9 8, and a connecting rod 182 couples the crank arm 100 to the bracket 86 on the manifold 38.

Therefore, as the actuating mechanism 92 moves the actuating rod 90 back and forth, the resulting angular reciprocal movement of the shaft 98 causes the upper manifold 38 to move reciprocally in the Y direction in its particular plane.

The rates at which the actuating mechanisms 82 and )2 drive the manifold 3-8 are controlled, so that the manifold 38 is moved reciprocally in its plane along both the Y and X axes as predetermined speeds.

The lower manifold 40 is mounted in the etching chamber 26 on a pair of cross bars 110 for sliding reciprocal motion transversely of the etching chamber 26. The lower manifold 40 is also mounted on rods, such as the rod 112, for sliding motion longitudinally in the etching chamber.

The common actuator rod 90 also controls the Y movement of the lower manifold 40 in its plane. For this purpose, the shaft 98 has a further crank arm 121) mounted on it. The arm 120 is coupled by. means of a connecting rod 122 to a bracket 124 on the underside of the lower manifold (FIGURE A further connecting rod 126 connects the lower manifold 40 to an actuating rod 128. The actuating rod 128 (FIGURE 8) is moved reciprocally by means of an actuating mechanism 130.

The common actuating mechanism 92, therefore, provides reciprocal motion for both the manifolds 38 and if? in their Y directions; where the independent actuating mechanisms 82 and 130 drive the respective upper and lower manifolds 38 and it) along the X axis.

All the components and support members described above are constructed of etchant impervious material, such as polyvinyl chloride. The actuator shafts may be composed of titanium.

The details of the actuating mechanism, such as the actuating mechanism 82, are shown in FIGURE 9. It will be understood that the other actuating mechanisms 92 and 138 may be similarly constructed, It is also to be appreciated that the actuating rods 78, 128 and 90 may be driven reciprocally by any other appropriate actuating means.

The actuating mechanism 82, for example, includes an electric motor 134 which has a drive shaft 136. The drive shaft 136 drives a crank 138. A roller 140 (composed, for example, of nylon) is rotatably mounted on a dowel pin 142 at one end of the crank 138, and this roller is mounted in a slot in a block 146. The block 146 is affixed to the actuating rod 78. The actuating rod 78 is mounted in suitable oilite bushings 151) and 152 for a reciprocal movement with respect to the actuator 82, when the motor 132 is energized.

The actual details of the upper manifold 38 are shown in FIGURE 10. It will be appreciated that the lower manifold 40 may be similarly constructed. The manifold 38 is composed, for example, of a plurality of tubular members, which are arranged in the manner shown to have a peripheral portion, and a plurality of transverse portions. The pressurized etchant is introduced to the interior of the manifold, in the manner shown in FIG- URES 3 and 4, for example.

A plurality of spray nozzles are mounted in the manifold, and are designated in FIGURE 10. These nozzles may be of the construction shown in FIGURE 11, and they are constructed to produce a uniform conical spray having a solid, uniform spray area. This assures that a uniform spraying pattern is provided, as the manifolds 38 and 40 are moved reciprocally in the manner described above.

The nozzles 16%, as mentioned above, may be composed of a suitable etchant resistive material, such as polypropylene. The nozzles may be of the type described in Patent 2,305,210 which issued December 14, 1942.

The nozzle 160 includes a base portion 160a which is relatively long so as to avoid water-hammer effects, as explained above. The base portion 168a defines an internally threaded portion 168!) at its upper end, and this portion receives a nozzle body portion 1600.

The body portion 1680 has external threads which permit it to be threaded into the portion 16Gb of the base 1641a. The nozzle body portion 1600 defines an internal mixing chamber, and it has a discharge orifice 160d at its upper end.

The internal mixing chamber of the nozzle body portion 1600 accommodates a cylindrical swirl member 160e. The swirl member comprises a pair of semi-elliptical intersecting vanes, arranged angularly as shown to impart a swirling movement to the etchant under pressure passing through the nozzle.

Each of the vanes mentioned above is provided with a notch, and these notches impart a counter-swirl or turbulence to the central portion of the stream. This provides an action to the etchant which causes it, after passing through the mixing chamber, to discharge from the orifice 168d in the form of a uniformly distributed spreading spray.

As mentioned above, it is important that the temperature of the etchant be controlled within close limits. This is achieved by the system shown in FIGURE 12.

A cooling coil 188 is mounted in the etchant storage reservoir 34, and the cooling water flowing through the coil is controlled by a solenoid valve 182.

An electric heater 186 is also mounted in the storage tank, and the electrical connections to the heater are made, for example, by a pair of electric leads 188. Under an automatic thermostatic control, when the temperature of the etchant in the storage tank 34 drops slightly from a preset temperature, the heater 186 is eneri'gized so as to bring the temperature of the etchant solution back up to the preset temperature.

On the other hand, when the temperature rises slightly above the preset temperature, the solenoid valve 182 is activated, so as to permit cooling Water to flow through the coil and return the temperature to the desired level.

As mentioned above, the cooling coil may be composed of the titanium, for example; and the heater 186 may be encased in titanium, so as to preclude attack by the etchant solution.

The pallet system is shown in FIGURE 13. The pallet 199 moves along a pair of hollow pipes 280, which are positioned in the etching chamber 26. The pallet itself is mounted on rods 202 which move telescopically in the hollow pipes 2110. Corresponding seals 2% are provided at the inner ends of the rods 202. A pair of longitudinal support bars 205 are mounted in the rinse chamber 12, and the pallet 199 has an apertured transverse end member 207 which is slidably mounted on the bars 205.

When the pallet 30 is to be moved into the etching chamber 26, it is pushed manually to the right in FIGURE 13, so that the rods 282 move telescopically into the tubes, or pipes, 200. A check valve 209 permits water in the pipes 200 to be discharged without activating the rinse nozzles in the rinse chamber.

At the completion of the etching cycle, a solenoid valve 206 in the pipeline 210 extending to the pipes 200 is activated, so as to permit water under pressure to enter the pipes 200. The resulting hydraulic action causes the pallet 30 to be moved to the left in FIGURE 13 and into the rinse chamber 12. When the pallet reaches the end of its travel and is in the rinse chamber, sufficient water pressure builds up in the pipeline 212 which extends to the rinse manifolds 18 and 20 and to the nozzles 22 and 24, so that a rinsing spray is initiated in the rinse chamber. After a predetermined interval, the solenoid valve 206 is automatically de-energized. Then the rinse chamber may be opened and the workpiece removed.

In order to prevent puddling of the etchant on the upper surface of the workpiece, when the workpiece is undergoing treatment in the etching chamber 16, a rocking mechanism is provided which periodically rocks the pallet 199 to cause any excess etchant to flow off the top surface of the workpiece.

The rocking mechanism is shown in some detail in the fragmentary perspective views of FIGURES 14 and 15. As shown, a bracket 400 is affixed to the coupling between the connecting rod 94 and actuating rod 90. The bracket 400 extends transversely to the axis of movement of the actuating rod 90 and it moves back and forth with the actuating rod as the latter moves reciprocally, as explained above.

A ratchet 402 is hinged to the end of the bracket 400. All these elements, and those to be described may be composed, for example, of polyvinyl chloride, or other appropriate etchant impervious material.

A dog 404 is mounted on a shaft 406 which, in turn, is rotatably mounted on the end of the etching chamber 26, on a pair of brackets 408.

Then, each time the rod 90 moves to the left in FIG- URE 14, for example, the hinged ratchet 402 is moved over the dog and falls of its own weight into position. When the rod 90 subsequently moves to the right in FIGURE 14, the ratchet engages the dog and moves the shaft 406 angularly by a predetermined amount. A stop member 410 prevents back movement of the dog.

A fiat paddle member 412 is supported on the shaft 406. As shown in FIGURE 15, this paddle member engages the edge of the pallet 199 and it causes the pallet to rock each time the rod 90 moves to the right. This rocking action of the pallet continues during the entire etching operation.

The system of the invention may be controlled by an electrical control system, such as shown in FIGURE 16.

The electrical control system of FIGURE 16 includes a transformer 300 which provides the power to the system. The primary winding of the transformer 300 may be connected to a usual 220-volt alternating current source; and the secondary winding of the transformer provides, for example, 115 volts alternating current. One side of the secondary winding is connected to a common lead 302 which is shown as grounded.

A filament transformer 304 is connected across the secondary winding of the transformer 300, and the latter filament transformer 304 provides 63 volts alternating current for the various indicating lamps of the system.

The load-unload pump 36 is connected into the circuit, and this pump is energized by means of a doublepole single-throw start switch 306. When the switch 306 is depressed, and indicating lamp 308 is connected across the filament transformer 304, and it glows accordingly showing that the load-unload pump 36 is activated.

The switch 306 also completes a circuit to a relay 310, so as to cause the arm of the relay to move from a normally-closed contact to a normally-open contact. The arm is connected to the ungrounded side of the secondary winding of the transformer 300. The pump 36 is now energized, and it remains energized so long as the switch 306 is depressed.

An interlock is provided by the normally-closed contact of the relay 310, so that power is supplied to the remaining portion of the system, only if the load-unload pump is not activated. This power is supplied to a first timer 312 and through a normally-closed contact of that timer to a second timer 314. The first time can be set, for example, to times up to 60 minutes; and the second timer can be set to times up to seconds.

The rinse solenoid valve 206 is connected in circuit with a timer 316. The timer 316 is connected in circuit with the timers 312 and 314, as shown. The motors of the actuators 82, 90 and are connected in circuit with a timing sequence relay 318. The pump motors for the etchant pumps 42 and 44 are also connected in circuit with the timing sequence relay 318 through corresponding double-pole, single- throw switches 320 and 322. Indicator lamps 324 and 326 are associated respectively with the switches 320 and 322. The motors of the etchant pumps 42 and 44 are energized through respective controllers 328 and 330.

At the beginning of the operation, and assuming that the load-unload pump 36 is de-activated, either or both of the switches 32-0 and 322 may be actuated manually. This causes the corresponding indicator lamps 324 and 326 to glow.

Assuming that both of the switches 320 and 324 have been activated; and the timer 312 has been set to a particular time, so that its normally-open contact is closed. The motor associated with the timer is energized and it will open the contact after the set time has elapsed.

The timing sequence relay 318 is energized, and current is supplied to the controllers 328 and 330 through its normally-open contact. The etchant pumps 42 and 44 are now energized, and etchant is pumped under pressure to the manifolds 38 and 40. Also, the actuating mechanisms 82, 90 and 130 are energized so as to impart reciprocal motion to the manifolds.

The timer 316 closes its normally open contacts after a predetermined interval as determined by its initial setting. This energizes the rinse solenoid valve 206, so that the pallet 199 is returned to the rinse chamber under hydraulic action, as described above; and the rinse sprays are subsequently activated in the rinse chamber, as also explained.

The timer 312 must cut off, terminating the etchant spray and the actuation of the etchant manifolds, before power is supplied to the rinse solenoid valve 206, by way of the contacts of the timer 316.

If the timer 314, rather than the timer 312, is set, then the timing sequence relay 318 is not energized, and power is supplied through the normally-closed contacts of that relay.

The thermostat control of the heater 186 may be through a relay 350. Whenever the temperature drops below the preset level, the thermostat energizes the relay which turns on the heater. The cooling valve 182 can be energized by closing a switch 352. When that occurs, an indicator lamp 354 glows.

The invention provides, therefore, an improved, fully automatic chemically milling and etching machine. The machine of the invention, as described above, is simple, sturdy and rugged in its construction. It is fool-proof and easy to operate. And, it performs its function in a rapid and efiicient manner.

While a particular embodiment of the invention has been described, modifications may be made. The following claims are intended to cover all modifications which fall within the scope of the invention.

What is claimed is:

1. In an etching machine of the type in which an etchant is continuously sprayed against the workpiece, the combination of: a housing defining an enclosed etching chamber and an accessible rinse chamber; pallet means for the workpiece mounted in a first horizontal plane and slidable between said rinse chamber and said etching chamber; at least one manifold movably mounted in said etching chamber in a second horizontal plane spaced from and parallel to said first horizontal plane; a plurality of spray nozzles mounted on said manifold, pump means coupled to said manifold for supplying pressurized etchant to said spray nozzles, and actuating means coupled to said manifold for imparting reciprocal motion to said manifold along mutually perpendicular axes in said second plane.

2. The combination defined in claim 1 and which includes hydraulic means coupled to said pallet and responsive to pressurized fluid introduced thereto for returning said pallet to said rinse chamber.

3. The combination defined in claim 1 which includes a plurality of rinse nozzles in said rinse chamber, and pipeline means for supplying pressurized water to said rinse nozzles; and which further includes hydraulic means coupled to said pipeline means and to said pallet and responsive to water pressure in said pipeline means for returning said pallet to said rinse chamber.

4. The combination defined in claim 3 and which includes check valve means coupled to said pipeline to prevent water from issuing from said nozzles when said pallet is moved from said rinse chamber to said etching chamber.

5. In an etching machine of the type in which an etchant is continuously sprayed against the workpiece, the combination of: a housing defining an enclosed etching chamber, an etchant reservoir and an accessible rinse chamber adjacent said etching chamber; pallet means for the workpiece mounted in a first horizontal plane and .slidable between said rinse chamber and said etching chamber; a pair of manifolds movably mounted in said etching chamber in spaced horizontal planes respectively above and below said first horizontal plane; a plurality of spray nozzles mounted on each of said manifolds, pump means having intakes coupled to said reservoir and outlets coupled to said manifolds for supplying etchant solution from said reservoir under pressure to said spray nozzles; and actuating means coupled to said manifolds for imparting reciprocal motion to said manifolds along mutually perpendicular axes in each of said spaced horizontal planes.

6. The combination defined in claim 5 and which includes removable filter means disposed in said reservoir and coupled to said intakes of said pump means.

7. The combination defined in claim 5 and which includes thermostat controlled heating and cooling means mounted in said reservoir for maintaining the temperature of the etchant solution therein at a pre-set level.

8. The combination defined in claim 5 and which includes a rocking mechanism coupled to said actuating means and engaging said pallet for imparting a rocking motion to said pallet.

9. The combination defined in claim 5 and which includes a load-unload pump coupled to said reservoir.

References Cited by the Examiner UNITED STATES PATENTS 764,164 7/1904 Thorpe et al. 134-474 2,029,563 2/1936 Elkington 134l8l X 2,036,232 4/1936 Kinzler 13482 X 2,392,540 1/1946 Lyman 134-180 X 2,566,142 8/1951' Powers 134'82 X 2,721,566 10/1955 Brucker 135-111 X CHARLES A. WILLMUTH, Primary Examiner.

ROBERT W. MICHELL, Examiner.

ROBERT L. BLEUTGE, Assistant Examiner.

Claims (1)

1. IN AN ETCHING MACHINE OF THE TYPE IN WHICH AN ETCHANT IS CONTINUOUSLY SPRAYED AGAINST THE WORKPIECE, THE COMBINATION OF: A HOUSING DEFINING AN ENCLOSED ETCHING CHAMBER AND AN ACCESSIBLE RINSE CHAMBER; PALLET MEANS FOR THE WORKPIECE MOUNTED IN A FIRST HORIZONTAL PLANE AND SLIDABLE BETWEEN SAID RINSE CHAMBER AND SAID ETCHING CHAMBER; AT LEAST ONE MANIFOLD MOVABLY MOUNTED IN SAID ETCHING CHAMBER IN A SECOND HORIZONTAL PLANE SPACED FROM AND PARALLEL TO SAID FIRST HORIZONTAL PLANE; A PLURALITY OF SPRAY NOZZLES MOUNTED ON SAID MANIFOLD, PUMP MEANS COUPLED TO SAID MANIFOLD FOR SUPPLYING PRESSURIZED ETCHANT TO SAID SPRAY NOZZLES, AND ACTUATING MEANS COUPLED TO SAID MANIFOLD FOR IMPARTING RECIPROCAL MOTION TO SAID MANIFOLD ALONG MUTUALLY PERPENDICULAR AXES IN SAID SECOND PLANE.

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