US3918363A

US3918363A - Multicolor sheet-fed printing press

Info

Publication number: US3918363A
Application number: US130167A
Authority: US
Inventors: Donald L Southam; Howard J Seel
Original assignee: Harris Intertype Corp
Current assignee: Harris Graphics Corp
Priority date: 1971-04-01
Filing date: 1971-04-01
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11
Also published as: DE2215505A1

Abstract

Multicolor sheet-fed printing press having a pair of two-color printing units, each of which includes horizontally offset upper and lower printing couples. The two-color units are likeconstructed and like-facing, and each is provided with an operator platform generally below and alongside the lower printing couple, whereby an operator on the platform can service both printing couples of a two-color unit from a single location. The two-color unit which is first to print sheets passing through the press is higher than the second unit, and a series of transfer cylinders are provided to carry sheets between the twocolor units.

Description

Unite States Patent [191 Southam et al.

[ Nov. 11, 1975 MULTXCOLOR SHEET-FED PRINTING PRESS [21] Appl. No.: 130,167

[52] U.S. Cl 101/183; 101/136 Harris 101/142 2,554,904 5/1951 Harrold 101/183 X 2,577,099 12/1951 Albrecht 101/183 2,757,610 8/1956 Gegenheimer et a1... 101/183 2,898,851 8/1959 Peyrebrune 101/136 3,527,164 9/1970 Bulk i 101/137 3,537,391 11/1970 Mowry... 101/230 X 3,570,398 3/1971 Mowry 101/183 Primary Examiner-=1. Reed Fisher [57] ABSTRACT Multicolor sheet-fed printing press having a pair of two-color printing units, each of which includes horizontally offset upper and lower printing couples. The two-color units are like-constructed and like-facing, and each is provided with an operator platform generally below and alongside the lower printing couple, whereby an operator on the platform can service both printing couples of a two-color unit from a single location The two-color unit which is first to print sheets passing through the press is higher than the second unit, and a series of transfer cylinders are provided to carry sheets between the two-color units.

4 Claims, 1 Drawing Figure U.S. Patent Nov. 11, 1975 MULTICOLOR SHEET-FED PRINTING PRESS Shortly afteer the second World War, certain printing press manufacturers introduced medium-sized twocolor sheetfed lithographic presses constructed with both printing couples mounted in a common frame. The printing couples were offset both vertically and horizontally to provide upper and lower couples. Alongside the lower couple was a platform on which an operator could stand to enable servicing either or both printing couples from one location. The success of these presses was and continues to be outstanding. An example of one type of two-color press referred to is shown in U.S. Pat. No. 2,542,867. This was followed in the late 1950s and early 1960s with four-color presses which essentially consisted of a pair of these two-color printing units connected together by what is commonly called a chain transfer system. Four-color presses of this type are illustrated in U.S. Pat. Nos. 2,705,918 and 3,527,164, and are commonly referred to as tandems in the printing trade.

Although chain transfer systems have been used satisfactorily for many years, they are not without limitations. For example, chain transfer systems are difficult to manufacture, assemble and maintain in a state of high accuracy for highest quality lithography. To have each of a plurality of chain transfer gripper sets repeatedly register identically with all other sets in receiving a sheet from one two-color printing unit and transferring that sheetto a subsequent printing unit is an accomplishment not easily obtained. Unless all the complex mechanisms are manufactured, assembled and continually maintained almost perfectly to tolerances of 0.001 inch or less, it is possible to get as many different color prints in each successive series of sheets as there are gripper sets in the chain transfer system. Misregister between the two-color units causes a fault commonly known as doubling Doubling occurs when some of the ink received by a given sheet from the first two printing couples is offset out of register onto the blankets of the third and fourth printing couples, and, by this ink being out of register with the next following sheet, the third and fourth couples print it back onto that next following sheet in an incorrect position. This misregister in multicolor half-tone printing has the effect of color change and the importance of accurate register to avoid such a result is too well known in highgrade lithography to require further comment.

it has been known that improved printing register is possible through use of a cylinder transfer mechanism between printing couples. However, the arrangement of the printing couples in the tandem presses shown in U.S. Pat. Nos. 3,527,164 and 2,705,918 is such that the number of cylinders required for sheet transfer is too great and too costly to justify conversion from the chain transfer system.

This invention relates to an improvement over conventional four-color chain transfer type presses wherein the first of the two-color printing units is ele- .vated above the second two-color unit, whereby a commercially feasible press capable of producing high quality lithography is provided with a minimumnumber of sheet transfer cylinders between the two-color units. In the preferred embodiment, an odd number of transfer cylinders is provided between the two-color units, all or certain ones of which are double the diameter of the cylinders of the printing couples.

The sole FIGURE illustrates a simplified side elevational view of a printing press embodying the invention.

In the preferred form of printing press illustrated, sheets are fed from right to left from a pile feeder 10, supporting and automatically raising a pile of sheets 11, from the top of which individual sheets are fed one at a time. A conventional sheet separating mechanism (not shown) is supported between side frames of the pile feeder above the pile 11. As sheets are separated, they are forwarded in underlapping stream fashion down an inclined feed table 12, at the lower end of which is a stock register unit 13. Each sheet is front and side registered in turn at the stock register unit, and is then fed to grippers on an impression cylinder 14 of a first printing couple 15. Generally, the printing couple 15 includes, in addition to impression cylinder 14, a

blanket cylinder 16, a plate cylinder 17 and, in the example illustrated, a combined inker and lithographic dampener 18 positioned above the plate cylinder 17. The printing'couple itself may be of any type, and the one shown herein is a commercial version presently on the market. Many details of the other printing couples of the press have been omitted, and it is to be understood that they are preferably of the same construction as couple 15.

As shown, the impression cylinder 14 rotates counterclockwise and provides a supporting surface for a sheet carried by gripper fingers 19. The fingers 19 transport the sheet in register through a printing nip formed by the cylinders 14 and 16.

Each sheet is thereafter transferred to gripper fingers on a transfer cylinder 50, which is shown as being twice the diameter of each of the cylinders of the first printing couple 15. The transfer cylinder grippers carry the sheet clockwise around its lower surface and transfer it to a second impression cyiinder 20 of a second printing couple 21. The sheet is subsequently passed around successive sheet-carrying transfer and impression cylinders 2227, all of which are shown as being double diameter transfer cylinders with the exception of impression cylinder 25 of the third printing couple 28 and impression cylinder 27 of the fourth printing couple 29.

After receiving the fourth color, sheets are transferred to grippers 30 of a delivery system including a delivery cylinder 31 and a continuous chain 32. The grippers 30 deposit sheets on the top of a pile 33, which is automatically lowered in the usual manner as sheets build up thereon. The chain 32 has a plurality of sets of grippers 30, only certain ones of which are shown, it being understood that they are equally spaced throughout the length of the chain. The main portion of the delivery system pile is supported in a pile delivery 34.

All of the cylinders described extend parallel to each other on horizontal axes between spaced side frames which journal the cylinders. The frames of the pile feeder 10, stock register 13 and the pile delivery 34 are similarly provided in spaced pairs. All of the frames are shown in dotted lines for ease of description.

' It will be noted that the printing couples l5 and 21 are mounted between side frames 35 while printing couples 28 and 29 are supported between side frames 36. The

side frames

35 and 36 may be made unitary or of subsections and, for all practical purposes, the frames are essentially the same. A principal difference is in the mounting of transfer cylinder 22 in frame 35 as compared to the mounting of delivery cylinder 31 in the side frame 36. The

side frames

35 and 36 are interconnected on each side of the press by subframes 37 which support transfer cylinders 23 and 24.

At the left and lower side of the printing couples 21 and 29 are located operator platforms 38 and 39, respectively. From platforms 38 and 39, an operator standing, stooping or kneeling on those platforms can service most, if not all, of the two printing couples and their inkers, depending on the construction of the twocolor unit. Installation of printing plates and blankets on their respective plate and blanket cylinders, servicing of the inkers, or washing any of the units can take place from the platforms 38 and 39 on the two printing couples immediately to the right of the platforms as shown in the drawing. As an example of this, one can refer to U.S. Pat. No. 2,542,867 issued to C. W. Harrold on Feb. 29, 1951. The press herein illustrated is essentially a pair of two-color printing units of the type illustrated in that patent.

Although two-color presses of the general type described above have been available on the world market for over years, it was not until the late 1950s that such presses were connected together to make a fourcolor printing press from a pair of these two-color printing units. Examples of such four-color presses can be seen in U.S. Pat. Nos. 3,527,164 and 2,705,918. The only known solution to the problem of making a fourcolor press out of a pair of these two-color units has been to utilize a chain transfer system approach as the method of transporting sheets between units. While a large number of such presses have been sold and are in use in the printing industry today, they sometimes have problems obtaining highly accurate printing register in multicolor work. Obviously, when using a chain transfer sytem, each of the plurality of gripper sets must be identical with all of the others, and must register perfectly to a first cylinder at one end of the chain transfer when they receive a sheet from one impression cylinder, and again register perfectly at the other end of the chain transfer when they give up the sheet to a subsequent impression cylinder. The manufacturing and assembling tolerance requirements in this type of mechanism are believed by many to be much greater and must be held more closely than in conventional cylinder transfer systems. Print repeatability is much more difficult to obtain when gripper sets are allowed to travel loosely supported by chains, then must be registered and locked to a cylinder mechanism before receipt of a sheet, again allowed to be loose on the flexible chain, and then finally re-registered and locked to another cylinder at the opposite end of the chain transfer. These presses are quite satisfactory for a large percentage of multicolor printing, but for top quality lithography, they must be manufactured with extreme accuracy and carefully maintained in that condition. Nevertheless, until this invention, the chain transfer system has been the only known commercial solution to the problem of providing a four-color tandem press by connecting a pair of two-color printing units of the type discussed previously. Certainly, cylinder transfer was known to be preferred, but to connect such a pair of two-color printing units by transfer cylinders in the normal way would require an excessive number of transfer cylinders between the pairs of units. Various transfer cylinder arrangements have been considered over the years, all resulting in designs with excessive numbers of cylinders, thus making them uneconomical to produce.

This invention makes it possible to obtain the advantages of cylinder transfer in a tandem four color press while avoiding the problems of cost and complexity which have resulted from attempts to substitute a cylinder transfer system in the same location as a chain transfer system. More specifically, this invention contemplates vertically offsetting side frame of the first two-color unit higher than frame 36 of the second twocolor unit. This is accomplished by placing a subframe beneath each of the side frames 35, so as to raise the entire two-color printing unit which contains printing couples 15 and 21. In this fashion, the pairs of twocolor units are maintained substantially identical, and remain compatible with the standard two-color presses of U.S. Pat. No. 2,542,867. It is preferred also to raise the pile feeder 10 by mounting beneath the side frames thereof, a pair of subframes 41. This provides a capability of handling higher piles of sheets 11 in the pile feeder 10, if desired. A standard-height feeder may be used, and in such case, an additional in-feed cylinder or cylinders would be located between the stock register unit 13 and the first impression cylinder 14.

A very important aspect of the invention is to provide a multicolor sheet-fed printing press which provides maximum accessibility to an operator for those things which must be done in preparing for printing, actually printing, and cleaning up after a printing job has been completed. Since an operator must frequently handcarry things to and from the press, such as a printing plate which is preferably carred with both hands, we provide a two-level platform 42 which is shown in dotdash lines. These platforms 42 are provided on both sides of the press to gain operator accessibility to all areas of the press. It will be noted that the lower level of the platform 42 is made to coincide with the upper surface of the platform 39, so that an operator servicing the printing couples 28 and 29 can do so by merely making one step up from the level of floor 43. To reach platform 38 to service printing couples l5 and 21, the operator can step up to the second level of the platform 42, and then up once again to platform 38. Platforms 38 and 39 extend fully across the press between the platforms 42 on each side thereof.

The press shown in the drawing provides all of the advantages of the chain transfer presses in terms of reduced manpower requirements, (since one operator can service two units), has only a slight disadvantage by having platform 38 raised three steps above the floor level, but has a very pronounced advantage in terms of accuracy of printing register by elimination of sheet transfer by gripper sets of a chain system. By raising the frames 35 which support the first two-color printing unit, it is possible to minimize the number of transfer cylinders required to carry sheets from the impression cylinder 20 of printing couple 21 to the impression cylinder 25 of printing couple 28. This is accomplished through use of three double-

size transfer cylinders

22, 23, and 24, but can also be achieved through use of single-sized cylinders or a combination of the two. Five cylinders would possibly be commercially acceptable. Since the two-color printing units shown already employ double diameter transfer cylinders and 26, the preferred arrangement of cylinders is to use similar double diameter transfer cylinders between the impression cylinders 20 and 25. This provides manufacturing advantages and further reduces the number of actual physical transfers of a given sheet through the press.

Starting at impression cylinder 14' where it passes a sheet to gripper fingers on transfer cylinder 50, it will be seen that there are only eight sheet transfers to the final gripper fingers on the impression cylinder 27 of the fourth printing couple 29. Thus, the use of doublesize transfer cylinders 22-24 reduces the number of actual sheet transfers to a minimum, while retaining the general configuration of'the two-color printing units which has been so successful in the printing industry. To provide accessibility to an operator or serviceman of the lower areaof the impression cylinder 27 and delivery cylinder 31, space 44.is provided below the subframes 37. A person can lie on a crawler board and roll himself into position horizontally below cylinders 23 and 24, from which he can reach cylinders 27 and 31. This access is also necessary in a four-color press using the common-impression cylinder arrangement for two printing couples as shown in US. Pat. No. 2,705,918, but only for access to its delivery cylinder. Other aspects of the invention are also believed applicable to such-a common-impression, two-color printing unit.

Although the invention has been described with reference to a specific embodiment, neither the illustrated embodiment nor the terminology employed in describing it is intended to be limiting; rather, it is intended to be limited only by the scope of the appended claims.

Having described our invention, we claim:

1. A multicolor sheet-fed printing press comprising first and second like-constructed and like-facing twocolor printing units each of which includes an upper printing couple having a first impression cylinder, a lower printing couple having a second impression cylinder which is offset downwardly and forwardly approximately 45 from the upper couple in a manner which eliminates the possibility of an operator standing between the upper and lower couples of each unit, and a transfer cylinder between the first and second impression cylinders of each unit and an operator platform below and along the side of the lower printing couple remote from the upper couple of each said two-color said number of transfer cylinders extending generally horizontally below the operator platform adjacent the lower printing couple of the first unit, the improvement comprising: said first two-color unit being located at a higher level than said second two-color unit whereby the lower printing couple of the first unit and the upper printing couple of the second unit are at approximately the same horizontal level' in order to minimize the horizontal distance said number of transfer cylinders extends I from the lower impression cylinder of the first unit to the upper impression cylinder of the second unit.

2. A printing press according to claim 1 wherein each of said impression cylinders is of the same diameter and rotates 360 in a single press revolution, and wherein each of the transfer cylinders of the two-color units and the transfer cylinders between units is twice the diameter of an impression cylinder and rotates 180 in a single press revolution.

3. A printing press according to claim 2 wherein the transfer cylinders between units are three in number.

4. A printing press according to claim 3 wherein the first and second of the between-unit transfer cylinders have their axes in approximately the same horizontal plane, and wherein the third one of said transfer cylinders is located upwardly and at an angle of approximately 45 from the second one of said transfer cylinders.

Claims

1. A multicolor sheet-fed printing press comprising first and second like-constructed and like-facing two-color printing units each of which includes an upper printing couple having a first impression cylinder, a lower printing couple having a second impression cylinder which is offset downwardly and forwardly approximately 45* from the upper couple in a manner which eliminates the possibility of an operator standing between the upper and lower couples of each unit, and a transfer cylinder between the first and second impression cylinders of each unit and an operator platform below and along the side of the lower printing couple remote from the upper couple of each said twocolor unit, each of said impression cylinders and the transfer cylinder of each unit having at least one set of sheet-carrying gripper fingers thereon, an uneven number of cooperating, adjacent transfer cylinders each of which includes at least one set of sheet-carrying gripper fingers thereon for receiving sheets from the gripper fingers of said second impression cylinder of the first unit and transferring them to the gripper fingers of the first impression cylinder of the second unit, said number of transfer cylinders extending generally horizontally below the operator platform adjacent the lower printing couple of the first unit, the improvement comprising: said first two-color unit being located at a higher level than said second two-color unit whereby the lower printing couple of the first unit and the upper printing couple of the second unit are at approximately the same horizontal level in order to minimize the horizontal distance said number of transfer cylinders extends from the lower impression cylinder of the first unit to the upper impression cylinder of the second unit.

2. A printing press according to claim 1 wherein each of said impression cylinders is of the same diameter and rotates 360* in a single press revolution, and wherein each of the transfer cylinders of the two-color units and the transfer cylinders between units is twice the diameter of an impression cylinder and rotates 180* in a single press revolution.

4. A printing press according to claim 3 wherein the first and second of the between-unit transfer cylinders have their axes in approximately the same horizontal plane, and wherein the third one of said transfer cylinders is located upwardly and at an angle of approximately 45* from the second one of said transfer cylinders.