US2283969A - Device for spraying printed sheets - Google Patents

Description

May 26, 1942.

DEVICE FOR SPRAYING PRINTED SHEETS Filed Feb. 27, 1939 vapart and cleaned.

Patented May 26, 1942 DEVICE FOR SPRAYNG PRINTED SHEETS Artur Bttner, Heidelberg, Germany, assignor to Schnellpressenfabrik Aktiengesellschaft Heidelberg, Heidelberg, Germany Application February 27, 1939, Serial No. 258,838

In Germany March 3, 1938 Claims.

pliances operated by compressed air are usually.

The liquid should employed for thisA purpose. only be sprayed on to the printed surfaces in quite definite quantities, in order to attain the requisite effect, and to prevent the superposed printed sheets sticking together.

Spraying devices are known in which a piston is displaced under the action of the compressed air, and thereby displaces, in the direction of an opening movement, a nozzle needle connected with it, which opens and closes the spraying nozzle. In order to prevent the spraying liquid from entering the space accommodating the -piston, `special packings must be provided for the nozzle needle. Since the needle is only of small diameter, this sealing gives rise to serious dmculties. A packing that is too tightly arranged hinders the movement of the nozzle needle, so that the latter does not quite close the mouth of the nozzle. Drops of liquid are thus formed on the nozzle, and drip on to the printed sheet. These dropshowever disturb the further treatment of the printed sheets by sticking the latter together. Under some circumstances such drops may hinder the execution of multi-colour printing. Notwithstanding the packings employed it has moreover not been found possible Vto prevent the spraying liquid reaching the chamber that accommodates the piston. The piston is therefore liable to jam', and it is then not possible to on to the sheet and to maintain the rhythmical operation of the spraying apparatus. The apparatus therefore has to be frequently taken This invention starts therefore from ani appliance in which a piston, moved by means of compressed air, and arranged in a separate chamber, acts by means of a lever upon the nozzle needle that closes the spraying nozzle. and imparts an opening movement to the needle.

Such apparatus is known for the spraying of paint and other liquids. In this known apparaare connected with the spraying device, one of which, the auxiliary pipe,.leads to a chamber containing lthe piston, and the second, the main pipe, leads to the spraying nozzle. The piston upon which the air supplied through the auxiliary pipe acts has to open from time to time a valve which is constantly subject to the pressure prevailing in the main pipe, or is kept closed by a. correspondingly strong spring.

This known apparatus, which is put into 'and out of operation by hand, and the manipulation of which may therefore take up any length of time, cannot be employed, owing tothe inertia of its parts, for sprinkling the sheets coming out of a printing machine with a medium for preventing olsetting because for the spraying operation controlled in a known manner by the printing machine only a fraction of asecond is available, and during this very short interval of 2'0 time quite a definite quantity of liquid has to be sprayed.

The disadvantage of this known apparatus is obviated by the` present invention, which consists essentially in the feature'that the compressed air required for the spraying operation is led into ing nozzle through this duct.

According to a further feature of the inventionA the structure of the spraying apparatusmay be such that a spring-loaded plunger which acts on the nozzle needle and a spring-loaded plunger which acts on the piston coacting with the nozzle needle are guided in a hinged cover of the casing, so that, after the cover has been hinged back, the nozzleneedle may readily be withdrawn for y cleaning pgirposes. It is therefore possible to clean the spraying apparatus without affecting .spray an accurately 'measured quantity of liquid the correct adjustment ofthe apparatus, which is. of greatimportance,-when cleaning is carried Voutduring operation. The adjustment may be Yina'de by an adjusting dev ice provided with a scale for regulating the lifting motion of the nozzle needle which determinesv the quantity of spraying medium iiowing out each time.

The spraying apparatus according to the invention is illustrated in one form of construc- H @dition by way of example in section, partly in side elevation, in the accompanying drawing.

The pipe I6, which'serves-for the supply of compressed air, for instance taken from a compressed air pump l0, leads to a chamber 26 which tus, however, two separate compressed-air pipes 53 is formed in the casing 25 of the spraying device and in which a piston 21 provided'with packing means 211 is vertically slidable. On this piston rests a lever 28 which is pivoted in the casing 25 on a pin 29. In the axial direction of the piston 21 there presses from above on the lever 28 a plungerv 3| which is guided in the cover 30 of the casing 25and which is acted on by a spring 32 and holds the piston 21 in its bottom position.

In the casing 25 is a secondchamber 33, into which a passage 34 opens. The latterds directly connected by an intermediate piece 36 containing a cock with a container 31 of transparent material for receiving the spraying liquid. By

closing the cock 35, for instance when the spraying device is to be cleaned, the admission of spraying liquid to the spraying device can .be

interrupted. Through a second cock 38 the container 31 can be emptied.

In the chamber 33 is fixed at the bottom a spraying nozzle 39 which is surrounded by an air nozzle 40. 'I'he latter is connected by a cap nut 4| with the casing 25. 'I'he conical outflow opening of the spraying nozzle 39 is closed in a fluid-tight manner by a nozzle needle '42 which is guided in a bore of the casing 25. This bore is provided at its upper end with a packing which can be adjusted by means of a screw 43. Against the adjustable head 421 of the nozzle needle 42 presses under the action of a spring 44 a plunger 45 which is guided in the cover 30 of the casing 25. The nozzle needle 42 is held in its closed position by this plunger 45.

In this arrangement, 'when compressed air is admitted to the chamber 26, the piston 21 is forced upwards and uncovers the opening of the passage 46 which leads to the air nozzle 40. Through this air nozzle only compressed air will thus at first ow out, before the liquid enters. During the upward motion of the piston 21 this piston forces the lever 28 upwardly. On the lever 28 are driver pins 41 which, during the further upward motion of the piston, bear from below against the adjustable head 421 of the nozzle needle 42 and raise the latter. -A small quantity of liquid will now be carried along by the compressed air owing out of the air nozzle 40 and will be atomised. The quantity of liquid to be atomised each time is easily adjustable by means of an adjusting screw 48 provided with an index arm movable adjacent a scale 49. By means of this adjusting screw 48 the lifting movement of the lever 28 is limited. When the compressedair inlet is shut off, for instance by means `of a valve, not shown, the springs 32 and 44 become effective. During the downward movement of the piston 21 the spraying. nozzle 39 is closed by means of the nozzle needle 42 and then the piston 21 closes the passage 46. Through the mode of operation of the spraying device, just described, the nest atomisation of the spraying medium is always brought about, without the formation of drops or large particles which would leave traces on the printed sheet or cause disturbances in the further treatment of the sheets. Moreover, the spraying gun according to the invention operates automatically, without mechanically or electrically controlled valves for determining the moment of spraying, when the air pressure is reached, which is necessary for overcoming the force of the springs 32 and 44.

For the purpose of cleaning the spraying, nozzle, the nozzle needle and so forth, the cover 30 which is pivoted about a pin 50 can be hinged back after the release of a closing screw 5|. The nozzle needle can then be readily withdrawn. No change is made in the previously eiected adjustment of the parts, so that thedescribed co-opererrors due to faulty adjustments of the device become impossible.

In the constructional example shown in the drawing the arrangement is such that for the production of the-compressed air for atomising the spraying liquid the air pump provided on a sheetfeeder is used.

' The cylinder 1 of this compressed air pump is mounted on the frame of the printing machine so as to oscillate in a bearing bracket 8. The piston l0 of this pump is in usual manner moved to and fro by means of the piston rod 3. Through drawing out the piston rod 3 a suction action is produced and the suction side of the pump cylinder 1 is connected by means ofa hose or pipe connection I4 with suckers (not shown) ofa sheet-feeder. On the piston rod 3 being pushed into the cylinder, compressed air is produced, which in accordance with the invention is used for the spraying device. For this purpose -the compression side of the pump cylinder is conin the hollow space 2| by a leaf spring 23 provided with an abutment plate 24 and the passage 221 leading into the hollow space 2|1 is closed by a leaf spring 31 provided with an abutment plate 241. In th' arrangement, on the piston Il of the air pump performing its suction stroke, the spring-loaded valve 23 which closes the suction pipe |4 will open, and at the same time the spring-loaded valve 231 of the;y compression pipe I6 will be forced against its seat and thus closed. Conversely, on the pump piston performing its compression stroke, the spring-loaded valve 23 is forced against its seat and closed, while the spring-loaded valve 231 is opened, so that the compresed air passes from the pump cylinder I0 into the compression pipe "6 and thence to the spraying device. ff

In printing machines having no automatic sheet feeder a separate air pump may be used.

I claim: l

1. A spraying device of the kind described, comprising in combination, a casing having/two chambers, a reservoir for a spraying liquid connected to one of said chambers, a spraying nozzle connected to the same chamber, a nozzle needle for closing said spraying nozzle, a spring-load pressure plunger for holding said nozzle needle in its closed position, an air nozzle surrounding said spraying nozzle, a piston movable in the second chamber, said second chamber being arranged separate from said nozzle needle, an air 'I'his makes the spraying device extremely A air nozzle and having an` admission port in thev p ath, of said piston, a spring-loaded pressure bolt for holding said piston in aposition for closing Asaid air admission port, a compressed air conduit connected tothe last saidchamber, and a lever for lifting said nozzle needle and actuated by said piston. v

2. A spraying device oi' the kind described, comprising in combination, a casing having two chambers, a reservoir for a spraying liquid connected to one of said chambers, a spraying nomle connected to the same chamber, a nozzle needle for closing said spraying nozzle. a spring-loaded plunger for holding said nozzle needle in its closed position, an air nozzle surrounding said spraying nozzle, a piston movable in the second chamber,

said second chamber being arranged separate from said nozzle needle, an air duct connecting haid second chamber with said air nozzle and .having an admission portin' the path of said plunger guided in said cover and adapted to acton said lever and to hold said piston in a position for closing said air admission port, a compressed air conduit connected to the second chamber, and A" an adjusting device arranged on said cover and adapted to limit the lifting movement lever. .f

4. A spraying device of the class described, comprising in combination, means forming two chambers, a reservoir for a spraying liquid connected to one of said chambers, a spraying nozzle connected to the same chamber, a nozzle needle of s'aid 'for closing said spraying nozzle, an air nozzle surrounding said spraying nozzle, a piston movable in the second chamber, said second chamber being separate from said nozzle needle, an air duct connecting said second chamber with acting on said lever and holding said piston in a position for closing said air admission port, a compressed air conduit connected to the second chamber, and an adjustable stop to limit the lifting stroke of said lever. I

3. A spraying device of the kind described, comprislng in combination, a casing having two chambers, a detachable cover on said casing, a reservoir for a spraying liquid connected to one of said chambers and carried by said casing, a spraying nozzle connected to the same chamber, a nozzle needle for closing said spraying nozzle, a spring-loaded plunger guided in said cover and adapted to hold said nozzle needle in its closed position, an air nozzle surrounding said spraying nozzle, a piston movable in the second of. said two chambers, said second' chamber being ar-V ranged separate from said nozzlevneedle, an air duct connecting said second chamber with said air nozzle and having an on port in the also acting on said lever to hold said nozzle needle said air nozzle and having an admission port in the path of said piston, a lever for lifting said nozzle needle and actuated by said piston, spring means for holding said piston in a position for closing said air admission port, said spring means also acting on said lever to hold said nozzle needle valve closed, and a compressed air conduit connected to the second chamber.

5. A spraying device of the class described, comprising in combination, means forming' two chambers, areservoir for a spraying liquid connected to one of said chambers, a spraying nozzle connected to the Vsame chamber, a nozzle needle forv closing said spraying nozzle, an air nozzle surrounding said spraying nozzle, a piston movable in the second chamber, said second chamber being separate from said nozzleneedle, an air duct connecting said second chamber with said means for holding said piston in a position for closing said air admission port. said spring means nected to the second chamber.

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