US2177877A

US2177877A - Etching machine

Info

Publication number: US2177877A
Application number: US111089A
Authority: US
Inventors: Harry G Pfaffmann
Original assignee: BURGER BAIRD ENGRAVING Co
Current assignee: BURGER BAIRD ENGRAVING Co; BURGER-BAIRD ENGRAVING Co
Priority date: 1936-11-16
Filing date: 1936-11-16
Publication date: 1939-10-31
Anticipated expiration: 1956-10-31

Description

Oct. 31, 1939. PFAFFMANN 2,177,877

ETCH'ING MACHINE Filed Nov. 16, 1936 2 Sheets-Sheet l IN VENTOR,

J6 By 1%?! 'y 177159276017.

Patented Oct. 31, 1939 PATENT orriee ETCHING MACHINE Harry G. Pfafimann, Kansas City, Mo., assignor to Burger-Baird Engraving Company, a corporation of Missouri Application November 16, 1936, Serial No. 111,089

6 Claims.

This invention relates to "electrical etching machines and has for one of its, primary objects, the provision of means for more evenly and uniiormly etching printing platesv of relatively large areas through the use of a main and supplemental grid forming the cathode in the machine while the piate being etched constitutes the anode.

a Oneoi the important aims of this invention is the provision in an electricaletching machine of the aforementioned character, of a supplemental cathode which is supplied in addition to'the main cathode of the apparatus, and in such relation thereto and to the plate being etched as to produce highly desirable and unexpected results without complicating the machine nor adding to the cost of operation.

A number of minor objects will appear during the course of the following specification, referring to the accompanying drawings, wherein:

Figure 1 is a front elevation of an electrical etching machine made in accordance with the present invention. I

Fig. 2 is a top plan View of the same.

Fig. 3 is a vertical, sectional View through the machine, taken on line III'III of Fig. 1.

Fig. 4 is an enlarged, detailed, longitudinal section through one of the plate, holders of the machine, and, v

Fig. 5 is a diagrammatical viewillustrating the electrical relation between. the anode and cathodes of the machine.

Referring to the drawingsillustratingthe preferred embodiment of the invention, the numeral fidesignates a vat or like container for the bath 8. This bath 8 may be ofthe conventional, well known character, but in practicing the invention, it has been found thatv a saturated solution of ordinary salt (NaCl) is satisfactory.

This bath, sometimes called an electrolytic bath,

m is a conductor and serves to submerge the hereinafter described anode and cathodes. Vat 6, supported by legs or standards in, is provided with an outwardly extending shelf 12, upon which is mounted a motor I LhaVing a worm l6 secured M to its shaft. Pinion 18, in mesh with worm l6,

50 i8, eccentric to its axis of rotation. I

One end of rocker arm 20 carries a pintle' 28 that is journalled in bearings 30 mounted upon shelf l2. The other end of rocker arm 20 is bifurcated and the opposing jaws formed by the 55 bifurcation-are provided respectively with slots 32, wherein rides cross pin 34, traversing yoke 36. Yoke 3% is substantially Y-shaped and the leg thereof is in connection with the upper end of rocker arm'iifl through the medium of the aforesaid cross pin 34. The two legs of yoke 36 are secured to the movable rack 38. This rack is substantially U-shaped and comprises legs in, conheated by a number of slats 42, upon which rests asupplemental grid M. Rack 3a is mounted for movement through the employment of tracks it, .1 one of which is mounted along the top of vat 6, adjacent each end thereof, and guide bars 43,

that are maintained in parallelism with each track respectively by brackets 58. Rollers $2, mounted upon legs til, ride along tracks 3B so as 15 to impart rectilinear reciprocating movement to rack 38 as motor M drives the aforementioned intermediate mechanism during the etching operation.

Main grid 56 is large enough to underlie grid 20 44 and plate 62 during the entire rectilinear reciprocating movement of grid and plate i i and 62 respectively.

Spacer blockst l in the bottom of vat ii, support main grid 56 in spaced relation to the floor of vat ii and below slats i2. A bus bar 558 rests upon the upper edges of legs it and carries two or more fixtures Ell that support plate 82 to be etched. These fixtures are specially formed and shown in detail in Fig. 4. The body thereof is preferablybreated of. non-conducting material and has a longitudinal bore G l extending inwardly from a notch 65 that is formed adjacent one end of the body. A strap 88, having a hook it formed at the outer end thereof, longitudinally 35 traverses thebody of fixture 6E and terminates at an inturned foot 712 within notch 86. This foot 12 is faced as at i l with a silver coating so that plate 62 might contact the same.

To hold plate 82 against face "Hi, there is provided a plunger 16 of non-conducting material that is extended outwardly at one end in the form of a threaded shaft 18. A coil spring at urges plunger Hi against plate 62 and turning thumb nut 82 will overcome the force of spring tit and 45 withdraw plunger it from engagement with plate 62 when it is desired to remove the plate from the fixture. Usually two of fixtures 6|] are provided and mounted upon bus bar 58, as shown in Figs.

1 and 2. i

These fixtures 68 should be formed to hold plate 62 in spaced, parallel relation with supplemental grid 44, and this last mentioned grid has an area .much smaller than the area of main grid 56.

Sincesupplemental grid 44 is carried by rack 38,

it will be stationary with respect to plate 62 that is also carried by rack 38 and both 44 and 62 will be movable with respect to main grid 56 in relatively spaced paths and in paths spaced from and parallel to main grid 56.

In all instances, grid 44 and plate 62 have their centers on a common line or in alignment vertically and grid 56 is large enough to always extend beyond the edges of grid 44 and plate 62 during the etching operation so that the center of the plate being etched will be etched as deeply as the marginal portions thereof. Thus one of the most troublesome shortcomings of electrical etching machines is overcome.

Reference to Fig. 5 will teach the manner in which plate 62, forming the anode, and

grids

44 and 56, forming the cathode, are joined to a conventional source of current 84. This source of current may be a generator of commercial type, and plate 62 is connected to the positive pole thereof by wire 86 and straps 68 of fixture 60. The cathodes in the form of

grids

44 and 56, are joined to the negative pole of generator 84 by a wire 88, so that the circuit is completed to eifectively electrically etch plate 62.

It is conceivable that machines having widely varying characteristics might be made to embody this invention, and while the preferred form has been illustrated and described, it is desired to be limited only by the spirit of the invention and scope of the appended claims.

Operation When plate 62 is in operative position in fixtures 60 with its face side down and in a horizontal plane, motor I4 is started and current for generator 84 directed through the circuit above traced. Grid 44 and slats 42 of rack 38 will agitate the electrolytic bath between main grid 56 and plate 62 sufficiently to wash the face of plate 62 and keep the same clear of deposits and bubbles.

Main grid 56 is always large enough to underlie grid 44 and plate 62 and the throw of link 22 and arm 2!] may be altered as desired.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An electrical etching machine comprising an electrolytic bath; means for supporting a plate therein to be etched; mechanism for moving said supporting means through a path of travel; conductors connecting the plate, which forms an anode, with the positive pole of a source of current; a main grid having an area appreciably greater than the plate in spaced parallel relation with said plate; a supplemental grid, shorter in length than the anode plate, carried by the plate supporting means, between the said plate and said main grid for movement with the plate; and conductors connecting the main grid and the supplemental grid, forming cathodes, to a source of current said main grid being great enough in area to have a portion thereof in opposed relation to the plate and supplemental grid as the same are carried by the supporting means as it moves through said path of travel.

2. An electrical etching machine comprising an electrolytic bath; means for supporting a plate therein to be etched; mechanism for reciprocating said supporting means; conductors connecting the plate, which forms an anode, with the positive pole of a source of current; a stationary main grid in spaced parallel relation with said plate; a supplemental grid, shorter in length than the anode plate, carried by the plate supporting means, between the said plate and said main grid for movement with the plate; and conductors connecting the main grid and the supplemental grid, forming cathodes, with the positive pole of the source of current, said supplemental grid being in spaced parallel relation with both the main grid and said plate said plate and the grids being in horizontal planes, said main grid being lowermost and having an area great enough to have a portion thereof below the plate and supplemental grid as the same are reciprocated by the supporting means.

3. An electrical etching machine comprising an electrolytic bath; means for supporting a plate in a horizontal plane therein to be etched; mechanism for reciprocating said supporting means; conductors connecting the plate, which forms an anode, with the positive pole of a source of current; a stationary main grid in spaced parallel relation with said plate; a supplemental grid, shorter in length than the anode plate carried by the plate supporting means, between the said plate and said main grid, for movement with the plate; and conductors connecting the main grid and the supplemental grid, forming cathodes, with the positive pole of the source of current, said main grid, being below the said plate in a horizontal position, said supplemental grid being spaced from and parallel to both the main grid and said plate for the purpose specified the main grid being extensive enough in area to underlie the plate and supplemental grid as the same are reciprocated.

4. In an electrical etching machine having an electrolytic bath, a plate therein to be etched forming an anode, and a main grid forming a cathode, the combination of a supplemental grid, shorter in length than the anode plate, forming a part of the cathode disposed between the main grid and theplate having an area appreciably less than the area of the main grid and having its center in alignment with the center of the plate, said supplemental grid and the plate being mounted for movement through the bath in paths spaced from and substantially parallel to the main grid, said plate and the supplemental grid being in spaced parallel relation to each other the area of said main grid being great enough to have a portion thereof opposite the plate and supplemental grid throughout their paths of travel.

5. In an electrical etching machine having an electrolytic bath, a plate therein to be etched forming an anode, and a main grid forming a cathode, the combination of a supplemental grid, shorter in length than the anode plate, forming a part of the cathode disposed between the main grid and the plate, said main grid having an area appreciably greater than the area of the plate and extending beyond the edges thereof,

6. An electrical etching machine having an electrolytic bath, a plate therein to be etched forming an anode, and a main grid forming a cathode, the combination of a supplemental grid, shorter in length than the anode plate, formingv a part of the cathode disposed between the main grid and the plate having an area appreciably less than the area of the main grid and having its center in alignment with the center of the plate, said supplemental grid and the plate being mounted for movement through the bath in paths spaced from, substantially parallel with and in opposed relation to the main grid.

HARRY G. PFAFFMANN.