US3272175A - Vapor deposition means for strip-coating continuously moving, helically wound ribbon - Google Patents

Description

Sept. 13, 1966 A LORENZ ETAL 3,272,175

VAPOR DEPOSITION MEANS FOR STRIP-COATING CONTINUOUSLY MOVING, HELICALLY WOUND RIBBON Flled May 12, 1965 2 Sheets-Sheet l FIG.1 3'

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l lLU INVENTORS. F'G. 3 b ALBERT LORENZ PAUL MULLER WALTER REICHELT 52 RICHARD SEIZ BERNARD Rossrvsrocx A\\\ WIIIIIIIIIIIIIIA ATTORNEYS Sept. 13, 1966 A. LORENZ ETAL 3,272,175

VAPOR DEPOSITION MEANS FOR STRIP-COATING GONTINUOUSLY MOVING, HELICALLY woum) RIBBON Flled y 1 1965 2 Sheets-Sheet 2 INVENTORS.

ALBERT LORENZ PAUL MULLER WALTER RElcHELT RICHARD SEIZ BERNARD RosErvsTocK ATTORNEYS United States Patent "ice VAPOR DEPOSITION MEANS FOR STRIP-COAT- ING CONTINUOUSLY MOVING, HELICALLY WOUND RIBBON Albert Lorenz, Hanan am Main, Paul Miller, Hanau- Kesselstadt, Walter Reichelt and Bernhard Rosenstock, Hanan am Main, and Richard Seiz, Bruchkobel, Germany, assignors to W. C. Heraeus Gesellschaft mit beschrankter Haftung, Hanan am Main, Germany, a corporation of Germany Filed May 12, 1965, Ser. No. 457,249 4 Claims. (Cl. 11849) This invention refers to apparatus for partially coating metallic ribbons under vaucuum by evaporation of the coating material comprising a noble metal, such as, silver.

In earlier times electrical contacts have been made entirely of noble metals, especially with silver. But in later times they have been stamped from metal ribbon which were covered with silver only at the area or strip serving as the contact surface when the contact spring has been formed. Usually only one flat side of the ribbon is coated and only a part, e.g. a half of this side. But the invention is not restricted to metallic coatings of metallic ribbons. It can also be used for coating with other materials.

An object of this invention is to provide an improved manufacture of such partially coated metallic ribbons.

More specifically, it is an object of this invention to provide an easy coating of ribbons of a substantial length.

It is another object of this invention to coat metallic ribbons of definite length, e.g. about 200 m.

Another object of this invention is the partial coating of metallic ribbons of indefinite length which are coated by a continuous coating process.

More specifically, an object of this invention is to improve the coating of ribbons of substantial length under vacuum.

Processes for vacuum coating of long metallic ribbons are known in the art. Also are known, processes for the partial coating of such ribbons. In these processes masking ribbons are used, which cover that part of the ribbon which shall remain free from the coating. The masking ribbon moves with the same speed as the ribbon to be coated and usually is in contact with this ribbon during the coating process itself. However, this has a number of disadvantages.

The masking ribbon must be moved with exactly the same speed as the metallic ribbon to be coated. This can only be fulfilled accurately by controlling the speed of both ribbons for which a complicated controller must be provided. Moreover, the openings or the masking edges of the masking ribbon are coated every time they are in use' So the openings or the masking edges gradually change their shape and also the configuration of the coated surface of the metallic ribbon.

It is an object of this invention to avoid such masking ribbon and still obtain the desired effect of partially coating.

The invention consists in winding the metallic ribbon to be coated on a cylinder, whereby the turns cover one another partially. At an invariable length of e.g. 100 or 200 m., the whole length of the ribbon is wound on a cylinder of suitable dimensions. The cylinder with the ribbon thereon, will be inserted into a vacuum chamber and coated in the usual manner by evaporating the coating material and condensing it on the free surface of the ribbon. A substantially greater length is wound in the same manner on the cylinder, but it is fed continuously by unrolling from a spool and after the coating process, it is rolled upon another spool which is advantageously driven by an electric motor.

3,272,175 Patented Sept. 13, 1966 For a better understanding of the invention together with further objects thereof, reference is made to the following descriptions, taken in connection with the accompanying drawings showing preferred embodiments thereof.

In the drawings:

FIGURE 1 is a cross-sectional view of a coating device forming an embodiment of this invention;

FIGURE 2 shows, partially in cross-section, the most essential part, the cylinder with the metallic ribbon wound on it;

FIGURES 3a and 3b show a ribbon partially coated according to the invention;

FIGURE 4 is a cross-sectional view of another embodiment of this invention;

FIGURE 5 shows a cross-sectional view through the cylinder of FIGURE 4; and

FIGURES 6 and 7 show other cross-sectional views of this cylinder.

The drawings are schematic ones in which all details of no importance for the understanding of the invention are omitted. The coating devices are shown especially without constructional parts for holding the different details and without pump sets for generating the necessary vacuum. Such constructional parts and pump sets suitable for the mentioned purposes are known in the art and need no explanation herein.

FIGURE 1 shows a vacuum chamber A with the cylindrical central part having flanges 2 and 3 on both ends. It is closed by the covers 4 and 5 which also are furnished with flanges 2' and 3. The flanges 2, 2' and 3, 3, respectively, are pressed together and sealed by the gaskets 2" and 3". The covers are movable and are supported by a construction not shown which can be moved in the direction of the axis of the cylinder 1 on rails, not shown.

The cylinder 1 is furnished with a sight glass 6 for observing the coating process. At the lower side of the cylinder there is provided a pipe 7 with a flange connection 8 to the vacuum line 9. This line 9 forms the connection to a vacuum pump set, not shown which exhausts the volume of the vacuum chamber A in the direction of the arrow 10. This pump set in the usual manner is furnished with vacuum gauges, vacuum controllers, floating valves etc. The apparatus is grounded by connection 77.

To the cover 4 at the right hand side of the drawing is fixed the motor housing 15 containing reduction gearing. The motor drives the shaft 16 extending into the vacuum chamber A and is sealed hermetically in cover 4. Said shaft 16 ends in the electrically isolating part 17 which forms part of the end wall 18 of the cylinder drum 19. On this cylinder 19 the metallic ribbon to be coated is wound in a manner which will be hereinafter described in connection with FIGURE 2.

To cover 5 on the left hand side of the drawing is fixed a tubular member 20 extending into the vacuum chamber A. This tube member 20 supports the electric heating elements 21. The heating energy is fed by means of electric wire connections 22.

In the lower part of the vacuum chamber A are mounted evaporators 25 for the material with which the ribbon is to be coated. Here can be used evaporators of any kind known in the art. Suitable are coats of high melting metals like tungsten or rods of graphite etc. If a layer of a substantial thickness is desired, it is advantageous to feed the material to be evaporated into the evaporators 25 during the coating process. This is also known in the art and needs no further description.

The evaporators 25 shown in FIGURE 1 contain the material 25 to be evapoarte-d. They are heated by an electric current which is fed by electric wires 26 and the wire connections 27. The wires 26 are'fed into the vac-' uum chamber A through the hermetic seals 28.

The coating material usually gives off many gases during its first heating, and in the first moments of the process evaporates undesired contaminations contained in it. To prevent the contaminants from affecting the coating process, a screen 30 is provided which can mechanically be moved in and out of the direct path from the evaporators and the cylinder 19. It screens the ribbon from the condensation of undesired material if it is moved in. Screen is supported by movable arm 31 led into the vacuum chamber A through seal 32.

It is known in the art to clean the surfaces to be later coated by a glow discharge in the first time of evacuation. For this purpose an electric connection 35 is provided which is led through seal 36. This connection has a contact 37 sliding on the metallic end wall 18 of the cylinder 19. The connection 35 and the sliding contact 37 can be connected to a high voltage generator, not shown.

FIGURE 2 shows the cylinder drum 19 on which has been wound a length of metallic ribbon 40 to be metallized or coated. The first winding 41 has been applied to the left side of the cylinder 19. The next winding 42 partially covers the first winding. Also the following windings are applied in such a manner so that they cover a part, e.g. the half width, of every preceding winding. The last winding 43 is held by a simple clamping device, 44.

For producing metallic coatings according to the process given by the invention, the apparatus described in connection with FIGURES 1 and 2 is utilized in the following manner.

The cover 4 is removed from the middle part 1 to such a distance that the cylinder is outside of part 1. Then the metallic ribbon which earlier had been cleaned is wound on the cylinder 19 according to FIGURE 2 and the cover 4 is brought back to the position shown in FIG- URE 1 for hermetically closing the vacuum chamber A. The pump set is switched on and the vacuum chamber evacuated to the desired degree of vacuum. After this the high voltage generator is connected with the connection end 35 thereby generating a glow discharge between the cylinder 19 or the surface of the metallic ribbon wound on it and the other metallic parts grounded by the connection 11. This glow discharge cleans the surface of the ribbon to be coated from all vapors which may be condensed on it and facilitates the coating;

After this cleaning process, the heating current to the evaporators 25 is switched on. They reach a temperature sufficient for the evaporation of the material 25' after a limited time, e.g. 5 minutes. After an additional time, egg. 2 minutes, the screen 30 is moved out, and the coating of the ribbon 40 wound onto the cylinder 19 begins. During the coating process, the cylinder 19 rotates for equally coating of the entire free surface of the ribbon 40.

After a coating of desired thickness has been produced, the heating current to the evaporators is switched off and/ or the screen 30 moved in, the vacuum is compensated by llooding the vacuum chamber and the cover 4 removed for unrolling the coated ribbon.

FIGURE 3 shows the metallic ribbon in view (FIG- URE 3a) and cross-section (FIGURE 3b). The ribbon is partially coated by the layer 51. During the coating process the other part 52 of the ribbon was covered by the next winding according to the FIGURE 2.

The embodiment of the invention shown in the FIG- URES 1 and 2 is suitable for the coating of limited lengths of the metallic ribbon. On a cylinder 19 with a middle diameter, d, of approximately cm. and a length, l, of also about 100 cm. can be wound a ribbon length of 100 m., if the width of the coated part 51 FIGURE 3 is about 3 cm. Other dimensions of the cylinder and of the coated width will allow to coat even greater lengths.

The cylinder 19 shown in the FIGURES 1 and 2 has been drafted somewhat conically. This is especially advantageous as by this the surface to be coated is parallel to the axis of the cylinder 19 and can be coated equally by several evaporators 25, each of which has the same distance from its axis. The angle of the conus depends on the thickness of the ribbon and on the width of the coated part or stripe 51, FIGURE 3.

The FIGURES 4 to 7 show another embodiment of the invention, it is to be noted that same parts are indicated by same numbers.

The main difference between the embodiment already described .and this embodiment consists in the feature that the apparatus according to FIGURES 1 and 2 is designed for coating limited lengths up to e.g. 200 m. while the embodiment shown in the FIGURES 4 to 7 is capable of coating practically unlimited lengths of ribbons. The invention is applied to a continuous coating process as the ribbon is also wound onto a cylinder and one winding covers the next winding partially.

In FIGURE 4, a bar 101 is fixed to cover 4. This bar supports the cylinder 102 in the same manner as in FIG- URE 1, but the bar 101 and the cylinder 102 do not rotate. Onto the periphery of the cylinder, the metallic ribbon 103 is wound which is unrolled from spool 104 and after the coating process rolled upon the spool i105 driven by the motor 106. Spools 104 and 105 are also supported by the bar 101 so that they can be moved together with the cylinder 102 and the cover 4. The windings of the ribbon 103 cover one another partially as shown in FIGURE 2. The ribbon 103 slides on the cylinder 102 during the coating of its entire length.

FIGURE 5 shows how the coated ribbon is advan' tageously taken from the cylinder 102 to the spool 105. Near the periphery of the cylinder 102, a roller 106 is mounted in a slit in the cylinder. In the interior of cylinder 102, another roller 107 is so arranged that its axis forms an angle with the axis of the cylinder 102. Thus the ribbon 103 leaves the open end of the cylinder, eventually through an end slit provided therefore, in the direction to the spool 105 also disposed at an angle to the axis of cylinder 102.

Usually the ribbon 103 during the coating process can slide on the surface of the cylinder 102. If this is undesired or harmful or if the force for the transport of the ribbon seems to be too great, cylinder 102 can be furnished with rollers. Two perpendicular crosssections of such an arrangement are shown in the FIG- URES 6 and 7.

The shell 110 of cylinder or as shown in FIGURES 6 and 7, has spiral grooves 111 in which rollers 112 are inserted. Each of the spiral rolls 113 between the grooves 111 serves as a guide for one winding of the ribbon 103 as shown in FIGURE 6. The rollers 112 have different and gradually decreasing distances from the axis of the cylinder wall 110. The ribbon 103 forms a spiral, the diameter of which decreased to the left side of FIGURE 6. Thus the windings cover one another and can move without any sliding one on the other.

The coating process is performed in the same manner as above already described.

Cover 4 is removed from the middle part 1 and with this cover the bar 101 and the cylinder 102 and the holding devices for the spools 104 and 105, fixed and supported by bar 101. A spool 104 filled with the metallic ribbon is inserted into its holding device and the ribbon is wound around the cylinder 102, thread through the opening for the guide roller 106 in the side of the cylinder 102 and given onto the surface of the roller 107. Then the end of the ribbon is fixed on the spool 105.

In the meantime, the material to be condensed on the ribbon has been put into the evaporator 25. Then the cover 4 is moved and sealed to the middle part of the chamber. The pump set not shown, connected to the pipe line 9 is switched on and evacuates the vacuum chamber A to the desired vacuum. The glow discharge is ignited and switched off. Thereafter the vacuum chamber is evacuated to the vacuum necessary for the coating process. The heating of the evaporator is energised, and after some time the screen is moved out.

At this moment motor 106 is switched on which transports the ribbon from the spool 104 over the periphery of the cylinder 102. During the passage of the ribbon over the cylinder 102, it is partially coated by the material evaporated from the evaporator 25 at the lower side of the cylinder 102. The speed is so regulated that a coating is performed having the desired thickness.

Then the ribbon is rolled upon the spool 105. After exhausting the ribbon on the spool 104, the heating of the evaporator and the pump set are switched off, the evacuated space flooded to atmospheric pressure and the cover 4 removed. The coated ribbon with spool 105 are then taken from its holding device and a new ribbon may be inserted for a new coating process.

The heating device 21 provided in the apparatus shown in the FIGURES 1, 4 and 5 serves for heating the ribbon during the coating process. This improves the durability of the coated layer.

The coating process described works very well. Pre ferably, it is used for the coating of electric contact springs made of different sorts of brass, especially of a beryllium alloy. Such brass ribbons were coated with silver or other noble metals to different, desired thicknesses. Thin coatings are suitable for electric contacts which are switched only several times. Examples are the contacts of apparatus parts inserted into a frame from which they are removed only for repair purposes.

According to the invention, not only thin coatings were performed, the thickness of which is only several an (1/ 1000 mm.) but also substantially thicker layers up to 0.2-0.3 mm. were manufactured which serve as contacts for switches and controllers working many times every minute.

It is to be noted that the invention is not restricted to the metallic coatings described. It can be used also in the case of dielectric coatings applied to a part of surface of metallic ribbons. Such isolating layers can be useful in assembling electrical parts in a small volume.

Having thus described the invention, the following is claimed:

1. An apparatus for partially coating a flat elongated metallic ribbon comprising, in combination:

(a) a sealable chamber;

(b) means for evacuating said chamber;

(c) evaporator means in said chamber;

((1) a drum in said chamber spaced from said evaporator means, said drum having an axis and a conically tapering face about said axis;

(e) two reel means rotatably mounted in said chamber;

(f) a motor means for rotating one of said reel means;

and

(g) securing means for securing an elongated ribbon on said face in a plurality of axially consecutive turns in such a manner that each portion of said ribbon is parallel to said axis, and an edge portion of one turn overlaps an edge portion of an axially adjacent turn while the other edge portion of said one turn is overlapped by an edge portion of another axially adjacent turn, said securing means including a guide pulley for guiding a ribbon from the other one of said reel means over said face in said turns while respective portions of said ribbon are wound on said one reel means and said ribbon is moved longitudinally under the force of said motor means.

2. An apanatus as set forth in claim 1, further comprising means for moving said ribbon in the direction of elongation thereof over said face in said turns, said drum being secured against rotation about said axis.

3. An apparatus as set forth in claim 2, a plurality of support members mounted on said drum, respective portions of said support members jointly constituting a portion of said face, each of said support members being rotatable about an axis substantially parallel to the axis of said drum.

4. An apparatus as set forth in claim 3, wherein said support members are arranged in a helical row on said drum.

References Cited by the Examiner Lorenz et al.: German application No. 1,131,484, publication 6-14-1962, copy in 118-49, (1 sht. dwg., 2 pp. spec.).

MORRIS KAPLAN, Primary Examiner.

Claims (1)

1. AN APPARATUS FOR PARTIALLY COATING A FLAT ELONGATED METALLIC RIBBON COMPRISING, IN COMBINATION: (A) A SEALABLE CHAMBER; (B) MEANS FOR EVACUATING SAID CHAMBER; (C) EVAPORATOR MEANS IN SAID CHAMBER; (D) A DRUM IN SAID CHAMBER SPACED FROM SAID EVAPORATOR MEANS, SAID DRUM HAVING AN AXIS AND A CONICALLY TAPERING FACE ABOUT SAID AXIS; (E) TWO REEL MEANS ROTATABLY MOUNTED IN SAID CHAMBER; (F) A MOTOR MEANS FOR ROTATING ONE OF SAID REEL MEANS; AND (G) SECURING MEANS FOR SECURING AN ELONGATED RIBBON ON SAID FACE IN A PLURALITY OF AXIALLY CONSECUTIVE TURNS IN SUCH A MANNER THAT EACH PORTION OF SAID RIBBON IS PARALLEL TO SAID AXIS, AND AN EDGE PORTION OF ONE TURN OVERLAPS AN EDGE PORTION OF AN AXISLLY ADJACENT TURN WHILE THE OTHER EDGE PORTION OF SAID ONE TURN IS OVERLAPPED BY AN EDGE PORTION OF ANOTHER AXIALLY ADJACENT TURN, SAID SECURING MEANS INCLUDING A GUIDE PULLEY FOR GUIDING A RIBBON FROM THE OTHER ONE OF SAID REEL MEANS OVER SAID FACE IN SAID TURNS WHILE RESPECTIVE PORTIONS OF SAID RIBBON ARE WOUND ON SAID ONE REEL MEANS AND SAID RIBBON IS MOVED LONGITUDINALLY UNDER THE FORCE OF SAID MOTOR MEANS.

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