DK141813B - Automatic control mechanism for small offset printing machines. - Google Patents

Description

\ Ra / (11) PUBLICATION NOTICE 1 ^ 1813 DENMARK (SU int.ci.3 b ai l 39/16 // b 41 f 33/16 '(21) Application No 2254/71 (22) Filed on 11 May 1971 (23) Running Day maj May 1971 (44) The application submitted and the petition published on June 2, 1 9 ^ 0

Dl THE RECTORATE FOR

PATENT AND TRADE MARKET (30) Priority requested from it

May 11, 1970, 42593/70, JP

Dec 29 1970, 128172/70, JP

<71> KABUSHIKI KAISKA RICOH, 5-6, 1-chome, Naka-magome, Ota-ku, Tokyo, JP.

(72) Inventor: Tamaki Kaneko, c / o Kabushiki Kaisha Ricch, 5-6, 1-chome,

Naka-magome, Ota-Tcu, Tokyo, JP: Yoshiharu Iwanaga, c / o Kabushiki Kai = sha Ricoh, 5-6, 1-chome, Naka-magome, Ota-Icu, Tokyo, JP.

(74) Plenipotentiary in the proceedings:

The engineering firm Lehmann & Ree._ (54) Automatic control mechanism for small offset printing machines.

The invention relates to an automatic control mechanism for small offset printing machines.

An offset printing machine comprises, in principle, a mold cylinder on which a printing plate is placed, a tablecloth for transferring a printing ink image onto the copy sheet by means of the mold cylinder and a printing cylinder for pressing the individual copy sheets against the tablecloth. When printing by means of a printing machine of this kind, the following operations must be carried out: A color container in the ink must be provided with a color, a printing plate must be placed on the mold cylinder, the printing plate placed on the mold cylinder must be etched with a color-shading etching liquid, the etched printing plate must be applied printing ink, then the printing machine is supplied with copied printed sheets and finally the surface of the dew cylinder 2 is cleaned after finishing the printing of the desired number of copy sheets. With simple offset printing machines of the kind in question, the application of the printing plate and the application of etching fluid is not performed automatically, but is done manually by the person operating the machine.

In semi-automatic offset printing machines, the redirection from one of the above-mentioned operations to the subsequent one is usually done by means of repeated operation of switching rods. In this way, the operator moves a clutch rod manually in order to clutch positions for applying pressure plate, etching thereof, applying paint, removing the pressure plate and cleaning the dew cylinder.

Such a printing machine has certain disadvantages. The time spent on etching, color application and cleansing is determined each time arbitrarily by the operator so that different people achieve different results. In addition, the person operating the printing machine must constantly operate the machine manually to determine the number of copy sheets to be printed and to move the coupling rod to the consecutive operating positions.

To avoid these drawbacks, a fully automatic offset printing machine was developed in which all work operations, after the person operating the machine has set the appropriate times for etching and wetting, color application and cleaning, are fully automatic by means of a push button. When operating a start button, a pressure plate is first applied automatically and etching fluid is applied. At the same time, an automatic reading assembly reads one of the operator on the non-printing surface portion of the printing plate, indicating the number of copy sheets to be printed and this reading is stored. After the time set for the etching and color application has been set, copying and printing will start automatically. At the end of the printing of the predetermined number of copy sheets, further supply of copy sheets is interrupted by means of a control unit in the counter where the predetermined number of copies is stored. Finally, the cleaning of the dew cylinder follows for the predetermined period of time, after which printing of a printing plate is completed. At the end of printing a printing plate, after removing the plate from the mold cylinder, the subsequent plate is automatically applied so that the printing of several printing plates can be carried out automatically.

In the case of printing machines of the kind described above, manual intervention by the operating personnel during printing is no longer necessary. The person operating the machine must place markings only to indicate the number of copy sheets to be printed before beginning printing on the non-printing surface portions of the individual printing plates 3 141813. Such a printing machine requires, as auxiliary mechanisms, a mechanism for automatic transfer from one work operation to the next, safety mechanisms and an automatic reading apparatus as well as a control mechanism for controlling the order of operation of these mechanisms. In this connection, reference should be made to the description of Danish patent application No. 6923/69, which describes such a printing machine controlled by control circuits with thyristors. This results in a complicated design of the printing machine and large manufacturing costs for these. This is a disadvantage of the fully automatic offset printing machines which makes their use with unskilled personnel questionable. On the other hand, they allow one to set the time required for color application on the printing plate, i.e. the time between the onset of color application on the printing plate and the beginning of the transfer of the color image on the dew cylinder, the time required for the transfer of the color image on the dew cylinder. the time from the commencement of the transfer of the color image on the tablecloth to the commencement of the insertion of copy sheets, as well as the time needed for cleaning, based on the experience gained with known printing machines.

Relatively simple offset printing machines can also be controlled by means of control means with cam means, which are operated by means of a feedback mechanism, depending on the engine speed of the machine, and which cooperate with switches to provide control functions. However, due to the tight space conditions of modern compact offset printing machines, it is difficult to accommodate e.g. a single cam disk driven by the machine cylinder speed, which can cooperate with contacts for automatically controlling the printing preparation operations until the printing of the printing sheet feed, of the printing operations until the cutout of the printing sheet feed and of the finishing operations until the stopping of the cleaned machine, as it has to operate a fairly large number of contacts, it will have a substantial size, making it difficult to fit into small modern offset printing machines. In addition, the number of sheets to be printed must, of course, be varied, since the same number of sheets is not always printed with the aid of each printing plate, and such variation in the number of sheets printed is difficult to provide by using a single cam washer.

The present invention relates to an automatic control mechanism for small offset printing machines and having cam means cooperating with contacts for automatic control of the print preparation operations until the printing of the sheet feeding, the printing operations until the printing of the printing sheet supply, and of the finishing operations until the stopping of the printing operation. and the cam means being driven by means of a feed-forward mechanism in dependence on the cylinder speed of the machine. It is the object of the present invention to provide such a control mechanism which is suitable for incorporation in small offset printing machines and which simply allows variation of the number of printed sheets, and this is achieved according to the invention in that the comb members according to the invention are constituted by two cam discs, the first of which cooperates with switches for engaging the preparation operations, and the second cooperates with switches for switching on the post-processing operations, and the feedback mechanism is switchable for engagement with the first or second of the cam discs, and the engagement of the first cam disk is interrupted during the printing operation. Hereby a small and compact control mechanism is obtained, the division into two combs, the first of which controls the preparation operations, and the second controls the finishing operations, to provide a suitable division of the necessary contacts, so that they can be appropriately distributed between the two combs. to which this particular division provides a convenient opportunity for individual control of the number of printed sheets, namely by a simple interruption of the forwarding of the first cam, until the required number of sheets is printed. Thus, by means of the control mechanism according to the invention, a mechanical control of a relatively large number of contacts is made possible in a very safe manner, namely by mechanical influence of the contacts in question controlled by the number of revolutions of the machine's cylinders, thereby avoiding fluctuations which are readily produced in connection with pure electrical control of fast-moving printing machines, and such rpm control is advantageous in that the printing preparation operations and the finishing operations are similar, regardless of whether the printing speed is increased or decreased.

However, depending on which plates are to be pressed, a varying number of cylinder revolutions may be required to transmit the pressure image on the dew cylinder and the cleaning and stopping of the machine, and in order to achieve such individual adaptation of these operations to different printing plates, the contacts which cause transfer of the pressure image on the dew cylinder, the pressure sheet insertion and the completion of the cleaning and stopping of the machine according to the invention are adjustable along the curve path of the associated cam. Such adjustability is made possible by the control mechanism according to the present invention thanks to said division into two cam disks which, despite the small size of the mechanism, provide sufficient space for the contacts to be adjustable.

According to the invention, the cam discs can each be connected to a pawl wheel, and the control mechanism can be provided with a switchable switching disc, by which one or the other of two pawl wheels belonging to one of their pawl wheels can be brought into and out of engagement with the associated pinwheel. This results in a simple switching between the cam disks which prevents the cam disks from being operated simultaneously, and yet the forwarding of the cam disks becomes simple as this is done by means of a weight arm, which Jean is given a driving motion at each cylinder rotation.

Furthermore, according to the invention, there can be found on each of the pawl wheels a non-toothed circumferential segment and each of the wheels can be provided with a return spring. Such a non-toothed circumferential segment is advantageous in that the pawl wheel in question can be brought to a standstill, even if the associated latch pawl is driven, thus, e.g. For example, the stopping of the forwarding of the first cam was performed at the beginning of the printing operation and the return by means of springs provides a very reliable return of the control mechanism so that it safely occupies the correct starting position when the printing preparation operations are to be initiated.

The invention will now be explained in more detail with reference to the drawing, in which: FIG. 1 shows a vertical view of the left side of an offset printing machine with an embodiment of the automatic control mechanism according to the invention; FIG. 2 is a vertical sectional view of a portion of FIG. 1; FIG. 3 is a side elevational sectional view of one embodiment of the control mechanism used in the offset printing machine of the invention; FIG. 4 is a sectional view taken along line III-III of FIG. 3, FIG. 5 is a sectional view taken along line IV-IV of FIG. 3, FIG. 6 is a perspective view of the control mechanism; FIG. 7 and FIG. δ operation of a switchable switch disc used in conjunction with the control mechanism; and FIG. 9 is a schematic diagram of the various operation steps of the offset printing machine according to the invention and the operation of the control mechanism and a counter.

In FIG. 2, a mold cylinder 1, a dew cylinder 2 and a pressure cylinder 3 are coupled together so that they rotate in the directions shown by the respective arrows. The cylinders 1, 2 and 3 are mounted between two side plates arranged parallel to each other. A control mechanism 5 for operating a color application assembly and provided with an electromagnet 6 is arranged in an upper part of the left side plate 4, and a control mechanism 7 with an electromagnet 8 for operating the color mechanism for transmitting the color image is located at the lower right of the control mechanism 5 and the electromagnet 6.

A copy sheet feed control mechanism 9 with an electromagnet 11 is disposed in a right portion of the left side plate 4, and a guide mechanism 12 with an electromagnet 13 for operating a cleaning mechanism is arranged in an upper left portion of the left side plate 4.

Mechanical timing means 14 driven by a weight arm 10 adapted to make a tilting motion each time the dew cylinder 2 turns, as will be described below, is disposed in the lower left portion of the left side plate 4. As will be described below, the timing means 14 comprises a first timing mechanism A and a second timing mechanism B, and there is an electromagnet 15 for switching between the two timing mechanisms.

16 is a start button for initiating the printing machine operation and 17 is a stop button for temporarily stopping the printing machine.

To the right of the buttons 16 and 17 is arranged a copy sheet counter 18 and a pointer lamp means 21 indicating the number of copy sheets set and stored in the counter 18 by a setting button 19. The number of copy sheets indicated by the pointer lamp means 21 , comprising pointer lamps 21a, 21b, and 21c are reduced each time a copy sheet is fed until the specified number becomes zero, after which the copy sheet feeding operation is interrupted.

In order for the aforementioned mechanisms to be made to operate in a particular consecutive order, it is necessary that the electromagnets of the various mechanisms at the beginning and end of each operation be supplied with a signal at a predetermined order and at certain times. The signals are output successively by the mechanical timing means 14. Construction and operation of an embodiment of the timing means 14 will first be explained and the mechanisms which are successively put into operation by the signals there given 4 * 7 U1813 by the timing means to set the various mechanisms. in progress, will then be explained.

Of all the above-mentioned printing machine operations, the operations are for loading and removing printing plates and for applying etching solution manually. All other operations from color applications to cylinder cleaning can be broadly divided into preparation, printing and finishing operations.

The preparation operations include the color application of the printing plate, the transfer of a color image of the printing plate to the dew cylinder and the feeding of copy sheets between the dew cylinder and the printing cylinder. Initiation of these operations is guided by the first time setting mechanism A, which is put out of operation as soon as the insertion of copy sheets has begun.

The printing or intermediate operation comprises the count of the number of printed sheets, the completion of the color application on the printing plate immediately prior to the completion of the printing, and the completion of the supply of copy sheets when printing is completed. The initiation of these operations is controlled by the copy sheet counter.

The finishing operations include the release and termination of the cleaning of the dew cylinder and the stopping of the machine. The control of these operations is accomplished by the second timing mechanism B.

The timing means 14 comprises the first timing mechanism A for controlling the preparation operations and the second timing mechanism B for controlling the finishing operations. Opposite ends of shaft 24 are secured by means of screws 25 and 26 to two covers 22 and 23, respectively, which are arranged parallel to each other. A flange 27 carrying the first timing mechanism A and a flange 28 bearing the second timing mechanism B are freely pivotally mounted on shaft 24 (Figs. 3-6).

A pawl wheel 29 and a first cam pulley 31 are disposed on opposite sides of flange 27 and are secured to each other and to the flange by means of screws 32. Similarly, a pawl wheel 33 and a second cam washer 34 are mounted on opposite sides of flange 28 and secured. to each other with screws 35.

A hub 36 firmly connected to a switchable switching disc 37 for the first timing mechanism A is rotatably mounted on shaft 24 by needle bearings 39 and 41, respectively.

A switch cam 42 for the second timing mechanism 141813 δ Β is secured with screws 43 to one side face of the switch disk 37 for the first timing mechanism A. As can be seen in FIG. 4 and 7, from the base of the switching disc 37, an arm 37a, which at its free end is connected by one shaft 45 to one end of an arm 44. The arm 44 is provided at its other end with a slot 44a, loosely accommodates a pin 46 which is attached to one side plate of the printing machine for supporting arm 44.

A tension spring 47 is disposed between a pin 44b attached to the arm 44 and a pin 49 attached to one of the side plates of the printing machine. A spring 48 is disposed between the pin 44b and a drive rod 15a of the magnet 15 attached to one side plate of the printing machine.

When power is applied to the magnet 15, the arm 44 is moved downwardly about the pin 46, thereby turning the switching disc 37 at an angle clockwise about the shaft 24 from the position shown in FIG. 7 to the position shown in FIG. 8. As shown in Figures 6 and 7, a pin 51a attached to a latch 51 and a pin 52a attached to a stop paw 52 are held in contact with portions 37b and 37c of relatively large diameter, respectively. the switch pulley 37 for the first timing mechanism A. The stop pawl 52 is rotatably connected at its base to a fixed portion (not shown), and the latch pawl 51 is pivotally connected at its base by a screw 54 (see Figs. 3-6) to a support 53 which is firmly blinded to the arm 10.

On the other hand, a pin 55a attached to a latch 55 and a pin 56a attached to a stop 56 are held against parts 42d and 42e, respectively, of relatively small diameter of the switch cam 42 for the second timing mechanism B The stopper 56 is pivotally connected at its base to a fixed portion (not shown), and the latch 55 is pivotally connected at its base through a screw 58 to a support 57 firmly connected to the arm 10.

As long as pins 55a and 56a attached to latch 55 and stop 56 respectively for the second timing mechanism B are held against. the smaller diameter portions 42d and 42a, respectively, of the switch cam 42, as shown in Figures 6 and 7, and the pawls 55 and 56 are engaged with the teeth of the pinwheel 33, the pins 51a and 52a attached to the latching pawl 51 and the stop pawl 52 are respectively held the first timing mechanism A, abutting the large diameter portions 37b and 37c, respectively, of the switching disc 37 of the first timing mechanism A, and the pawls 51 and 52 are kept out of engagement with the teeth of the pinwheel 29.

If, by magnetizing the magnet 15, the switch disk 37 and the cam 42 are moved from their in FIG. 7 to their positions shown in FIG. 8, the pins 55a and 56a attached to the posts 55 and 56, respectively, are brought into contact with the larger diameter portions 42b and 42c, respectively, of the switch cam 42, and the posts 55 and 56 are released from engagement with the teeth of the impeller 33. At the same time, the pins 51a and 52a attached to the piles 51 and 52, respectively, for abutting the smaller diameter portions 37d and 37e, respectively, of the switch washer 37, and the pawls 51 and 52 are engaged with the teeth of the pawl wheel 29.

Thus, it will be noted that the pallets 51 and 52 for the first timing mechanism A and the piles 55 and 56 for the second timing mechanism B are never simultaneously engaged with the pawl wheels 29 and 33, respectively, but that only the pallets for one of the timing mechanisms can be engaged. with its respective pal wheel.

Retraction springs 59 and 61 loosely disposed over cylindrical hubs on flanges 27 and 28, respectively, lie between the cover members 22 and 23 and the cam discs 31 and 34, respectively, which are firmly connected to the pulleys 29 and 33. The pulleys 29 and 33 are actuated by the return springs. 59 and 61 for counterclockwise rotation about the shaft 24 of FIG. 4 and 5. The angular rotation of the pawl wheels 29 and 33 produced by the return springs 59 and 61, respectively, is limited by suitable stoppers (not shown) in theirs in FIG. 4 and 5.

A color application initiator switch S2, a color image transfer initiator switch S3 and a copy sheet input initiator switch S8 are disposed around the outer periphery of cam 31 for the first timing mechanism A, as shown in FIG. 5. A cylinder cleaning start switch S7 and a cleaning finish and machine stop switch S are disposed around the outer periphery of cam disc 34 for the second timing mechanism B, as shown in FIG. 4. The aforementioned contacts are actuated as they are engaged by larger diameter portions 31a and 34a of cam discs 31 and 34, respectively, as cam discs 31 and 34 rotate in a counterclockwise direction about shaft 24.

The positions of the switches S3 and S8, as shown in FIG. 5, 141813, and the position of the switch S, as shown in FIG. 4 relative to the larger diameter portions 31a and 34a, respectively, can be adjusted from the outside. When setting these positions, it is possible to set appropriate time intervals for color application, color image transfer and purification operations.

If, after operation of a main switch, the start switch is operated by means of the start button 16 (Fig. 2), a motor starts to drive the mold cylinder 1, the dew cylinder 2 and the pressure cylinder 3 in the Figs. 2 with the respective arrows indicated. In addition, when operating the starting contact, the magnet 15 (see Fig. 4) is magnetized such that the arm 44 is moved downwardly against the force of the spring 47. The switch disc 37 is then moved from the one shown in fig. 7 to the position of FIG. 8, so that pins 55a and 56a of the latch 55 and stop 56 of the second timing mechanism B are brought into contact with the larger diameter portions 42b and 42c of switch cam 42, respectively, and the latch 55 and stop 56 are engaged from engagement with the teeth of the pawl 33. 51a and 52a on the ratchet pawl 51 and the stop pawl 52 respectively for the first timing mechanism A are simultaneously brought into contact with the smaller diameter portions 37d and 37e of the switch disc 37, respectively, and the ratchet pawl 51 and the stop pawl 52 are engaged with the teeth of the pinwheel 29.

Each time the dew cylinder 2 performs a rotation thereof with the arrow of FIG. 2, the weight arm 10 is tilted about the shaft 24 by being pulled by a follower arm.

Hereby the pawl wheel 29 is moved at an anti-clockwise direction around the shaft 24 by means of the ratchet pawl 51. While the pawl wheel 29 is rotating, the cam washer 31, which is fixedly connected to the pawl wheel 29, also rotates so that a roller on the contact S2 is moved outwards the contact S2 is thereby affected. The actuation of the switch S2 causes magnetization of the magnet 6 of the movement mechanism of a color application assembly.

After the ink application operation is initiated by actuation of switch S2, the pawl wheel 29 is moved forward with one tooth for each rotation of the dew cylinder 2, so that the cam washer 31 is rotated counterclockwise around the shaft 24 of FIG. 5. As the cam 31 is rotated, its large diameter portion 31a successively affects the contacts S3 and S8. Effect of contact S3 causes a color image of the printing plate to be transferred to the dew cylinder 2, and influence of the contact 11 U1813 S8 causes the start of copy sheet feeding to the printing cylinder 3.

With a traditional printing machine, the time intervals for performing color application, color image transfer and cleaning of the dew cylinder are set, without regard to other conditions. The amount of color applied to the printing plate on the foil cylinder, the thickness of a color image transferred to the dew cylinder, and the extent of the cleaning operation on the dew cylinder after completion of printing a predetermined number of copy sheets, becomes therefore greater for a given time interval as the number of engine revolutions increases. Conversely, this decreases as the number of revolutions on the motor is reduced. This disadvantage is removed by the invention because the control of the preparation operations, that is, the control of the initiation of color application, color image transfer and the copy sheet application by the first timing mechanism A, is done not only on the basis of certain time intervals, but on the basis of the number of revolutions of the dew cylinder 2. , so that color application, color image transfer and cleaning can be performed as planned without being affected by the speed of the dew cylinder.

The printing machine can e.g. is set so that the switch S3 is actuated so that color image transfer is initiated when the dew cylinder 2 has performed from two to twenty turns after the color application has been initiated by actuation of the switch S2. Generally, the printing machine is set so that the color image transfer begins when the dew cylinder 2 has performed approx. 10 turns. The contact S8 is affected such that copy sheet feeding to the printing cylinder 3 is initiated when the dew cylinder 2, after the contact S3 has been affected, has performed a number of turns (about 1-5) which provide a transfer to the dew cylinder of a sufficiently strong color image.

The time interval determined for color application and the time interval determined for color image transfer are shown in FIG. 9 denoted t1-t2 and t2-t3 respectively. The time intervals t1-t2 and t2-t3 can be varied by moving contacts S2 and S8.

In Fig. 5, the pawl wheel 29 is shown as having a non-toothed circumferential segment 29a on its periphery, with which segment of the latch 51 is arranged to come into contact when the larger diameter portion 31a of the cam 31 influences the copy sheet feed initiation contact S8. For this reason, the timing mechanism A is disabled from time t3 in FIG. 9, at which the copy feeding is initiated, the latching pile 51 merely performing reciprocating movements beyond the toothless segment of the pawl 51.

The copy sheet counter 18 is initiated as soon as copy sheet feeding is initiated to count the number of printed copy sheets. A predetermined copy number of copy sheets is set and stored in advance in the counter, and this stored number is reduced by one each time a copy sheet is printed until the number in the counter becomes zero. When there are no more copy sheets to print, the copy sheet feed is terminated by a signal from the copy sheet counter.

After the ink supply to the printing plate on the mold cylinder 1 has been completed, it is possible to print several copy sheets with the color remaining on the printing plate and on the color image on the dew cylinder.

By printing copy sheets without applying any additional color to the printing plate, the color image of the dew cylinder is attenuated, which facilitates the cleaning of the dew cylinder upon completion of printing. The copy sheet counter therefore emits a signal immediately before the completion of printing, or when there are approx. five copy sheets left to print, thereby terminating the ink application on the printing plate using the ink application assembly.

When printing is complete, in addition to the above-mentioned signal for ending the copy sheet feed, the copy sheet counter outputs a printing termination signal to the magnet 15 (see Fig. 5) at a time t5. At this signal, the magnetic coil 15 falls out and the arm 44 is retracted from the one shown in FIG. 5 to the position of FIG. 4 by the force of the spring 47, whereby the switching disc 37 and the cam 42 are retracted from theirs in FIG. 8 to the positions shown in FIG. 7 positions. As a result, the stop pawl 52 and the stopwatch pawl 51 are released from their engagement with the teeth of the pinwheel 29 for the first timing mechanism A, and the stopwatch pawl 55 and the stop pawl 56 for the second timing mechanism B are engaged with the teeth of the pinwheel 33, as shown in Figures 4 and 6. .

The pawl wheel 29 for the first timing mechanism A released from engagement with the stop pawl 52 is rotated clockwise around the shaft 24 by the force of the force shown in FIG. 3 and locking it with a fitting (not shown) fixed to a fixed portion for retention in its FIG. 5.

As seen in FIG. 4, the pawl wheel 33 for the second timing mechanism B is rotated in a counterclockwise direction 13 1A181 3 about the shaft 24 when the weight arm 10, on which the ratchet column 55 is pivotally mounted, performs a tilting movement for each rotation of the dew cylinder 2. The time of initiation of the operation of the the second timing mechanism B is indicated by t5. The contact S7 is actuated at time t5 by the large diameter portion 34a of the cam washer 34, thus opening to power supply to the cleaning assembly magnet 13 (see Fig. 2). In the continuous stepwise rotation of the impeller 33 in a counterclockwise direction about the shaft 24, the contact S is affected by the larger diameter part 34a of the cam washer 34, thereby terminating the cleaning.

The time interval for performing the cleaning can be set at will by adjusting the position of the switch S. This time interval can be set to correspond to two to twenty turns of the dew cylinder. Generally, the cleaning operation is performed while the dew cylinder does from three to fifteen turns. The time at which the contact S is affected is indicated by t7 in FIG. 9. Operating the switch S leads to the termination of the cleaning operation and stopping of the motor and thus of the printing machine.

As soon as the contact S is actuated by the cam disc 34, it is shown in FIG. 4, the toothed segment 33a of the pinwheel 33 of the second timing mechanism B is not shown to be adjacent to the ratchet 55, so that the second timing mechanism B is put out of operation.