GB2060495A

GB2060495A - A Printing Apparatus

Info

Publication number: GB2060495A
Application number: GB8032405A
Authority: GB
Original assignee: TC DRUCKMASCHINEN GmbH
Current assignee: TC DRUCKMASCHINEN GmbH
Priority date: 1979-10-10
Filing date: 1980-10-08
Publication date: 1981-05-07
Also published as: IT1212435B; FR2468469A1; DE2941031A1; IT8024967A0

Abstract

A printing cushion 1 is alternately moved between a position above an inked master 12 and a position above a support for the article 13 to be printed, in each position the cushion is then vertically reciprocated into contact with the stationary master or article. Preferably a plurality of cushions 1 are carried in sleeves 2 on a cross-head 3 rotatable on vertical shaft 4 so as to index the cushions between impression receiving and printing position; the shaft is axially reciprocated for the impression movements. <IMAGE>

Description

SPECIFICATION Improved Printing Apparatus A printing apparatus is known which has a printing cushion which is reciprocated between an upper retracted position and a lower printing position in which it makes contact with an article to be printed. During the downward stroke of the printing cushion, it is halted in contact with a master which transfers an inked impression to the cushion and is then withdrawn horizontally into a position in which the master is re-inked out of the path of the cushion while the latter continues its downward movement. To increase output, this type of apparatus is often provided with a number of printing cushions for the simultaneous printing of a plurality of articles.

This type of apparatus is costly to produce because of the need to provide a mechanism for moving the master between its withdrawn position in which it is inked and its advanced position in which the impression is transferred to the printing cushion or cushions. This mechanism must permit the movement of the master to be carried out accurately to ensure exact register with the printing cushion, especially in the case of multi-colored printing. Another disadvantage of this type of apparatus, is the fact that the movement of the master into the path of the printing cushion or cushions makes it difficult to insert into the apparatus the article or articles to be printed and, also, prevents the provision of automatic feed and delivery devices.

These problems are overcome by the apparatus disclosed herein which comprises means for supporting a stationary master and a stationary article to be printed, and a holder for at least one printing cushion, the holder being vertically reciprocable, and adapted to bring the or each printing cushion alternately into an impression receiving position above the master and into a printing position above the support for the article to be printed. With this arrangement, at least one printing cushion may be arranged on a beam capable of being rotated in a horizontal plane and of being moved upwards and downwards, so that each cushion is alternately placed in an impression receiving position and an impression transferring position, by turning the beam through a pre-set angle. The inking of the master using a squeegee may take place during rotation of the beam.Although it is convenient for the beam to be rotated through one-half turn between each axial reciprocation, since in this way it may always rotate in the same direction, it is possible for the beam to rotate through any other angle, performing a back and forth rotation movement between each axial reciprocation.

The beam may be supported by, or take the form of, a cross-head supported at one end of a rotatable axially reciprocable vertical shaft coupled at its other end to gearing for rotating it and to a crank mechanism for reciprocating it, the gearing and crank mechanism being driven alternately by a drive assembly. A convenient arrangement is achieved by mounting the beam at the upper end of the shaft and driving the shaft from its lower end, although an inverted arrangement is possible.

Registration of the impressions may be ensured by providing the beam or the shaft, or a part movable therewith, with a groove in which is received a stationary stop face formed, for example, by a guide strip or bar during the downward movement of the beam. Again, an inverted arrangement is possible, and a stationary part of the apparatus may be provided with the groove which receives a part carried by one of the movable components.

With the printing apparatus disclosed herein, the driving and control processes are mechanically determined without intermediate couplings requiring electrical control devices, as has been necessary with the previously known apparatus. The master is stationary and does not therefore need exact guidance and special fixing elements for multi-coloured printing. The printing cushion or cushions perform uninterrupted upward anddownward strokes of fixed length and the support for the articles to be printed is accessible from both sides and also from above, thereby making the insertion and removal of the articles easy to carry out, either manually or by automatic means, because the master is not moved into a position above the articles.

Because the master is mounted in a fixed position within the apparatus, it may be inked by a squeegee mounted in a slide movable along guides arranged at both ends of the master, the squeegee being pivotal about its longitudinal axis in the slide so that it can pivot to an ink application during one stroke across the master and into an ink scraping position during the return stroke. This. movement may be achieved by providing rocker levers at the ends of the squeegee and stationary stops disposed in the paths of movement of the rockers.

In the drawings: Figure 1 is a schematic view from the front of the proposed printing apparatus, Figure 2 is a view from the side of the apparatus, Figure 3 is a plan view of the apparatus, Figure 4 is a section through the drive mechanism for a vertical shaft of the apparatus, to a larger scale, Figure 5 is a sectional view looking from the left hand side of Figure 4, Figure 6 is a section taken through Figure 4 to show a Geneva mechanism, Figure 7 shows a plan view and to a larger scale a fragment of the apparatus to illustrate a guide device, and Figure 8 shows in plan view and to a larger scale a further part of the guide device.

Referring to Figures 1 to 3, the proposed printing apparatus comprises a support housing having an upper section 5 supporting a vertical shaft 4 which is axially reciprocable and rotatable by a drive mechanism contained in a lower housing section 6. The drive mechanism is powered by a motor 7 acting through a transmission 8. Mounted on the shaft is a crosshead 3 the ends of which are widened to provide to parallel support beams for two row of sleeves, each of which receives a printing cushion or pad 1. The pads are adjustable relative to the sleeves.

Projecting from one side of the housing section 5 is an arm 9 carrying a support beam for a row of sleeves, each of which is aligned with one of the sleeves 2 and supports adjustably a respective holding device 11 for a master 12. Projecting from the other side of the housing section 5 is an arm 10 carrying a support beam for another row of sleeves, each of which is aligned with one of the sleeves 2 and receives adjustably a support 13 for an article to be printed. The arms 9 and 10 are adjustable in height and arranged on diametrically opposite sides of the axis of the shaft 4. The beams carried by the arms are parallel to each other and at right angles to the arms.The master 1 2 on each of the holding devices 11 may be of any known form which permits an inked image to be transferred to a cushion 1 when it is pressed against the master.

Likewise, the cushion may be of any known type which will enable the image to be transferred to an article when the cushion is pressed against it.

Although the master may be in the form of a perforated stencil covering an ink pad, for example, it is preferably in the form of an etched plate or block to which ink is transferred by an ink roller or squeegee supported by a slide 14 but not shown in the drawings. The slide is movable along horizontal guides 1 5 by means of arms 1 6 articulated to cranks 17 of a shaft 1 8 drivable in rotation by way of toothed gearing from a gear wheel mounted on the shaft 4.

Briefly, in operation, the shaft 4 is rotated onehalf turn so that each row of cushions 1 occupies the position formerly occupied by the other, and at the same time the squeegee performs a reciprocating movement to ink the masters 12.

Thereafter, the shaft 4 is drawn downwards to transfer ink impressions from the masters 12 to the cushions shown at the right in Figure 2, and to transfer the impressions carried by the cushions shown at the left in the figure to articles resting on the supports 1 3. Other arrangements for inking the master are, of course, practicable.

The driving mechanism located in the lower housing section 6 for rotating and axially reciprocating the shaft will now be described with reference to the Figures 4 to 6. A shaft 4 is mounted in a pillow block 1 9 for rotation and axial movement. A connecting rod 21 is provided at its upper end with a spherical bearing 20 housed in a support secured to the lower end of the shaft 4 so that the connecting rod is free to swing from side to side withoutrotating with the shaft 4. Mounted on the support is a spur gear 28 by which rotation drive is transmitted to the shaft as will be described later.

The lower end of the connecting rod 21 has a bearing which receives the crank pin 22 of a crank 23 journalled within a sub-frame disposed in the lower part of the housing section 6 and suspended by rods from the cover of the housing section. Bolted to the crank 23 is a bevel gear 24 in mesh with a bevel gear 25 freely supported on a vertical shaft 26 fixedly mounted within housing section 6. Also freely supported on the shaft 26 is a spur gear 27 in mesh with the gear 28 fast with the shaft 4. The gears 25 and 27 are spaced from each other and located between them is a Geneva mechanism including a pair of discs 29 and 30 arranged freely on the shaft 26, the gear 25 being fixed to disc 29 and gear 27 being fixed to disc 30.A drive wheel 31 is keyed on a shaft 33 drivable by the transmission 8, motion being transmitted from the wheel 31 to the disc 29 by a pair of rollers 32 and to the disc 30 by a pair of rollers 33. The rollers 32 and 33 are mounted respectively on the lower and upper side of the wheel 31, each roller 32 being located diameterically opposite a roller 33 so that both rollers 32 will engage the disc 29 before the rollers 33 engage the disc 30. In Figure 6, one of the rollers 33 is shown engaged in the diametral slot of the disc 30 which is mid-way through an incremental step. The disc 29 shown in phantom is positioned ready to receive one of the rollers 32 following further rotation of the wheel 31. It will be appreciated from this figures that, during each rotation of the wheel 31, each of the discs 29 and 30 will be rotated through one-half turn.

Referring to Figure 8, one or each of two sides of housing section 5 has a groove in which a stationary index strip 35 of rectangular crosssection is held by inserts 38 bolted in place and engaging the lateral faces 35a of the strip to permit its adjustment and fixing. The strip projects above the housing section 5 into the lower position of the cross-head which has a vertical groove 34, the lateral sides 34a of which are formed by the surfaces of rollers 36. The rollers are journalled on shafts 37 adjustable transversely of the groove by means of bolts 39.

The rollers can also be stepped to form the internal faces of the groove. The rollers are positioned so that they engage the strip 35 during descent of the cross-head to lock the cross-head in position.

In operation, ink is supplied to an ink tray and motor 7 is started and drives the wheel 31 continuously in rotation by way of the transmission 8 and shaft 33. Assuming that the wheel 31 is positioned so that the rollers 33 are the first to take effect, the disc 30 is engaged and turned by each roller 33 through a quarter turn, passing through the position shown in Figure 6, thereby rotating the spur gears 27, 28 and shaft 4 by one-half turn. The cross-head 3 is consequently turned from the position shown in Figures 1 to 3 into the diametrically opposite position. At the same time motion is transmitted from a pinion on the shaft 4 by way of gearing not shown in the drawing to the shaft 1 8 to rotate the cranks 1 7 through one complete revolution.The rods 16 cause the slide 14 and the squeegee to be moved out of the ink tray, across the master 12 and back again. During its outward stroke, the lower edge of the squeegee slides on the masters at a small distance, permitting the application of ink to them. During the return stroke, the squeegee is pivoted by means of adjustable rocker levers arranged at the ends of the squeegee cooperating with adjustable stops, but none of which is shown in the drawings, in such a way that the lower edge of the ink pad rests on the surfaces of the masters and scrapes off excess ink.

With these movements completed and the cross-head in the diametrically opposite position from that shown, the rollers 32 engage the lower disc 29 to rotate it by a total of one-half turn, this motion being transmitted from the bevel gear 25 to the bevel gear 24 fast with the crank 23.

The ratio of the gears 24,25 is such as to produce a full revolution of the crank 22 and a complete reciprocation of the shaft 4. The crosshead descends so that the masters are contacted by one row of the printing cushions which take up the ink impressions. The cross-head then returns to its upper position, a row of articles are supplied to the supports 13, after which the Geneva mechanism causes rotation of the shaft by onehalf turn to restore the cross-head to the illustrated position and the re-inking of the master. The Geneva mechanism then causes the cross-head to descend, the transfer of inked impressions to the un-inked cushions, and the transfer of the impressions from the inked cushions to the row of articles, which are removed and replaced, and operation proceeds accordingly.

As the cross-head enters its lower position in which impressions are transferred from the masters to one row of printing cushions, and from the other row of printing cushions to the articles to be printed, the index strip 35 enters the groove 34 and ensures by contact with the rollers 36 an accurate positioning of the printing cushions relative to the masters and articles to be printed, thereby avoiding any iack of register caused by pl-ay in the driving system for the shaft 4. Multicolour printing may therefore be carried out accurately.

Changes may be made to the arrangement described above. For example, the shaft 4 might be arranged to extend downwardly from the drive housing, and carry the cross-head at its lower end. The cross-head may be provided with index strip or strips and the housing with the groove in which it is received. The groove may take the form of a recess which is surrounded on ali sides.

The supports 13 for the articles and the supports 11 for the masters 12 may be in each case replaced by a single support, and a single master with a plurality of impressions may be employed.

Each row of four cushions may be replaced by a single elongate cushion. Automatic means may be provided for feeding articles to the support or supports for the articles, and for removing the printed articles therefrom.

Claims

1. A printing apparatus comprising means for supporting a stationary master and a stationary object to be printed, means for inking the master, and a holder for at least one printing cushion, the holder being vertically reciprocable, and adapted to bring the or each printing cushion alternately into an impression receiving position above the master and into a printing position above the support for the object to be printed.

2. A printing apparatus according to Claim 1, including a beam for supporting the printing cushion or cushions, and means for rotating the beam in increments of one-half revolution, and means for inking the master during each such revolution.

3. A printing apparatus according to Claim 2, including a shaft supporting the beam for rotation and reciprocation, gearing for rotating the shaft and a crank mechanism for reciprocating the shaft, and a driving assembly for driving the gearing and crank mechanism alternately.

4. A printing apparatus according to Claim 2 or Claim 3, including a stationary guide strip or bar engagable in a groove in the beam at least during part of the vertical reciprocation of the beam.

5. A printing apparatus according to Claim 4, wherein faces of the groove are formed by the surfaces of rollers loosely mounted on a shaft capable of being eccentrically adjusted and secured.

6. A printing apparatus according to Claim 4 or Claim 5, wherein the strip or bar is of rectangular cross-section and is adjustable and securable by means of inserts capable of bearing against its lateral faces.

7. A printing apparatus according to Claim 3, including a double Geneva mechanism comprising a driving wheel disposed between axially spaced driven discs, each of which is drivable alternately by the driving wheel to operate the gearing and crank mechanism.

8. A printing apparatus according to Claim 7, wherein both driven discs are freely rotatable on a common shaft, one of said discs being fast with a spur gear for driving the shaft, and the other disc being fast with a bevel gear for driving a crank, the crank pin of which is articulated to a connecting rod connected to the shaft.

9. A printing apparatus according to any preceding claim, wherein the inking means includes a pad supported by slides movable along guides parallel to the ends of the master or masters.

10. A printing apparatus according to Claim 9, wherein the slides are drivable by a crank mechanism from the shaft by way of gearing.

11. A printing apparatus according to Claim 10, wherein the gearing is driven from a pinion on the shaft.

1 2. A printing apparatus according to any of Claims 9 to 11, wherein the pad is pivotable about its longitudinal axis so as to have an ink application position and an ink scraping position.

13. A printing apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A printing apparatus comprising a crosshead supported on a vertical shaft, impression receiving means supported by the cross-head on diametrically opposite sides of the shaft axis, a master support disposed below one said means, a workpiece support disposed below the other, and a drive mechanism for alternately reciprocating the shaft axially and rotating it through one half turn.