EP0444397B1

EP0444397B1 - Screen exchange apparatus in an automatic screen printing machine

Info

Publication number: EP0444397B1
Application number: EP19910100083
Authority: EP
Inventors: Shiro Ichinose
Original assignee: Toshin Kogyo Co Ltd
Current assignee: Toshin Kogyo Co Ltd
Priority date: 1990-02-28
Filing date: 1991-01-02
Publication date: 1994-07-20
Anticipated expiration: 2011-01-02
Also published as: KR960003330B1; EP0444397A3; EP0444397A2; DE69102904T2; DE69102904D1

Description

The present invention relates to a screen exchange apparatus in an automatic screen printing apparatus. More particularly, the present invention relates to a screen exchange apparatus in an automatic screen printing machine in which exchange, washing, drying, setting and withdrawal of screens are performed efficiently according to the operating and working cycle of the printing machine.
At the printing step in an automatic printing machine, operations of attaching, withdrawing, washing and moving screens have been heretofore mentioned as unreasonable operations where automation is most delayed. With recent development of a screen-washing machine, only the washing operation is substantially automated, see e.g. DE-A- 1 460 779. However, all of the operations of dismounting a screen from the printing machine, attaching a screen to the printing machine, moving a screen to the washing machine or screen store chamber, removing water after the washing and drying a screen are manually carried out.
Moreover, the quantity of one lot for the printing operation is now decreasing and the number of colors to be printed is increasing. Therefore, because of the necessity to exchange colors or patterns, the frequency of exchange of screens and the loss of time at the washing step increase, resulting in reduction of the effective working efficiency of the printing machine and also in reduction of the productivity in the printing process.
We found that a certain regularity resides in operations of exchanging, washing, drying, setting and withdrawing screens in an automatic screen printing machine, and that if this regularity is utilized, these operations such as exchange of screens can be reasonably performed at a high efficiency without any load imposed on an operator.
It is therefore a primary object of the present invention to enhance the efficiency of operations inevitably conducted in an automatic screen machine, such as exchange, washing, drying, setting and withdrawal of screens and to attain a labor-saving effect, especially automatization, in these operations, whereby the working efficiency of the printing machine is highly increased with a high rationalizing effect.
Another object of the present invention is to provide a screen exchange apparatus in an automatic screen printing apparatus, in which the foregoing operations inevitably conducted in the automatic screen printing machine can be performed smoothly with out any loss of time and without contamination of the working environment with a color paste or the like.
Still another object of the present invention is to provide a screen exchange apparatus in an automatic screen printing machine, in which withdrawal and setting of screens can be performed smoothly according to the order of the attachment of screens to the automatic screen machine.
In accordance with the present invention, there is provided a screen exchange apparatus in an automatic screen printing machine, comprising:
a plurality of going and coming guide rails disposed in parallel to the automatic screen printing machine to effect reciprocating delivery of screens;
a plurality of screen carriers for holding and delivering screens along said guide rails;
screen transfer means capable of moving and stopping along the going guide rails to effect transfer of screens between the automatic screen printing machine and the screen carriers;
screen raising and dropping means disposed between front and rear ends of the guide rails to raise the screen carriers from the going guide rails to the coming guide rails and to drop the screen carriers from the coming guide rails to the going guide rails;
screen washing and drying means disposed in the vicinity of the terminal end portion of the going guide rails to wash and dry used screens held and delivered by the screen carriers; and
screen-storing rack means comprising a plurality of screen-storing racks disposed at the starting end portion of the going guide rails to effect necessary storing and take-out of screens.
The screen exchange apparatus in an automatic screen printing machine according to the present invention can be applied to not only a flat type screen comprising a screen proper and a screen frame but also a rotary type screen.
Fig. 1-A is a plane view showing a main part of the automatic flat type screen exchange apparatus of the present invention, which is disposed in parallel to an automatic screen printing machine.
Fig. 1-B is a plane view showing a main part of the automatic rotary type screen exchange apparatus of the present invention, which is disposed in parallel to an automatic screen printing machine.
Fig. 2-A is a side view illustrating the main part shown in Fig. 1-A.
Fig. 2-B is a side view illustrating the main part shown in Fig. 1-B.
Fig. 3-A is a sectional view illustrating the main part shown in Figs. 1-A and 2-A.
Fig. 3-B is a sectional view illustrating the main part shown in Figs. 1-B and 2-B.
Fig. 4-A is a side view illustrating a main part of an automatic flat type screen exchange apparatus in which a residence zone is arranged in a washing and drying device.
Fig. 4-B is a side view illustrating a main part of an automatic rotary type screen exchange apparatus in which a residence zone is arranged in a washing and drying device.
The first characteristic feature of the screen exchange apparatus of the present invention is that there are going and coming guide rails arranged in parallel to the automatic screen printing machine, a plurality of screen carriers for holding and delivering screens along the guide rails are movably arranged on the guide rails, and a screen transfer means capable of moving and stopping along the going guide rails is disposed to transfer screens between the automatic screen printing machine and the screen carriers.
The operations of attaching screens to the automatic screen printing machine, detaching the screen therefrom, exchanging the screens and changing the color in the same screens are carried out through the operations of setting screens to the automatic screen printing machine and taking out screens therefrom. In the present invention, going and coming guide rails are disposed in parallel to the automatic screen printing machine, a plurality of screen carriers moving along the guide rails are disposed, and a screen transfer means capable of moving and stopping along the going guide rail is disposed, whereby the operation of setting and taking out screens can be performed at an optional position of the automatic screen printing machine by the screen transfer means, and the delivery of screens to this setting and take-out position and the detachment of screens from this position can be easily accomplished without any loss of time.
The going guide rail is disposed to effect delivery and withdrawal of screens through the screen transfer position. The second characteristic feature of the present invention is that a screen raising and dropping means is disposed at front and rear ends of the going and coming guide rails to raise screens from the going guide rail to the coming guide rails and to drop screens from the coming guide rail to the going rail. If this structure is adopted, the screen carriers can be circulated between the going guide rail and the coming guide rail, and the delivery and take-out of screens can be combined with the operations of storing, detaching, washing and drying screens, described hereinafter, without any loss of time.
The third characteristic feature of the apparatus of the present invention is that a screen washing and drying means is disposed in the vicinity of the terminal end of the going guide rail to wash and dry the used screen held and delivered by the screen carrier, and a screen-storing rack means having a plurality of screen-storing racks is disposed at the starting end portion of the going guide rail to effect necessary storing and take-out of screens. A color paste is inevitably left adhering to the screen taken out from the automatic screen printing machine. Accordingly, in the case where the color is changed in this screen or this screen is stored, it is necessary to remove the adhering color paste. In the present invention, since the screen washing and drying means is disposed in the vicinity of the terminal end portion of the going guide rail, washing and drying of the screen can be performed simultaneously with detachment of the screen, no particular labor or time is necessary for washing and drying. Moreover, since a screen-storing rack means is disposed at the starting end portion of the going guide rail, a new screen can be taken out from this screen-storing rack means and can be supplied to an optional position of the automatic screen printing apparatus through the going guide rail and the screen transfer means, and the screen which has been taken out, washed and dried can be stored in the screen-storing rack means through the coming guide rail. In the case where the color is changed in one screen, the washed and dried screen is supplied again to an optional position of the automatic screen printing machine by the screen transfer means through the coming guide rail, the screen raising and dropping means and the going guide.
In the case where the apparatus of the present invention is applied to rotary type screens, it is preferred that a rotary driving mechanism be mounted on the screen carrier so that while the screen carrier moves along the guide rails, especially the going guide rail, the rotary screen is revolved by the running power of the carrier. Even if a color paste-adhering rotary screen is moved, by revolving the screen, dropping of the color paste from the screen can be prevented, and contamination of the apparatus and working environment with the color paste can be prevented.
According to the present invention, by the synthetic combination of these features, the efficiency of the operations inevitably conducted in the automatic screen printing process, such as operations of exchanging, washing, drying, storing and taking out screens, is increased and a labor-saving effect is attained, and especially, automatization of these operations becomes possible, with the result that the working efficiency of the printing machine is greatly increased and high rationalization is achieved. Moreover, the foregoing operations can be accomplished smoothly without any loss of time and without contamination of the working environment with a color paste.
The present invention will now be described in detail with reference to embodiments shown in the accompanying drawings.
Referring to Figs. 1-A and 1-B, two automatic screen printing machines (hereinafter referred to as "printing machines")1-1 and 1-2 are arranged in parallel to each other, and devices 2-1 and 2-2 for introducing a fabric 4 to be printed are arranged on the front sides of the printing machines 1-1 and 1-2 (left sides in Figs. 1-A and 1-B) and printing driers 3-1 and 3-2 are arranged on the rear sides (right sides in Figs. 1-A and 1-B). The fabric 4 to be printed is introduced, and while the fabric 4 is intermittently driven in the direction indicated by the arrow in the drawings, the printing operation is carried out according to known procedures through a flat screen 5a in Fig. 1-A or a rotary type screen 5b in Fig. 1-B.
A screen exchange apparatus (hereinafter referred to as "exchange apparatus") 6 of the present invention is interposed between the two printing machines 1-1 and 1-2 in parallel thereto. In the present embodiment, two printing machines 1-1 and 1-2 are arranged on both the sides of the exchange apparatus 6. In this case, the loss of time can be reduced and the automatic exchange apparatus 6 can be operated at a high efficiency, as compared with the case where one printing machine is arranged. However, no particular trouble is caused even if only one printing machine is arranged.
In general, the exchange apparatus comprises the following members:

(1) two-staged going guide rail 7 and coming guide rail 8;
(2) a plurality of screen carriers 9 moving along the guide rails 7 and 8;
(3) screen transfer means 10 moving in the state suspended from the going guide rail 7;
(4) screen washing and drying means 11 disposed in the vicinity of the right terminal end portion of the going guide rail 7;
(5) screen-raising means 12-1 and screen-dropping means 12-2 disposed at both the ends of the guide rails 7 and 8.
(6) screen-storing rack means 13 arranged on the left end of the guide rails 7 and 8; and
(7) driving mechanisms and controlling means for driving and controlling the foregoing members according to the operating and working cycle of the printing machine, which are arranged according to need.

The driving mechanisms and controlling means are known, and therefore, illustration of these members in the drawings and description of these members are omitted.
The respective members of the exchange apparatus of the present invention will now be described.
Referring to Figs. 2-A, 2-B, 3-A and 3-B, each of the going guide rail 7 and coming guide rail 8 comprises two (a pair) of parallel rails spaced by a predetermined distance and having a length larger than the effective printing table length L of the printing machines 1-1 and 1-2 and covering the length of the screen washing and drying means 11 described hereinafter. The guide rails are arranged in parallel to the printing machines at a height H not disturbing the printing operation.
The going guide rail 7 and coming guide rail 8 are arranged between the screen raising means 12-1 and the screen dropping means 12-2 to act as rails for guiding a plurality of carriers 9 holding and delivering screens 5a or 5b.
The screen carrier 9 is circulated and moved along the guide rails 7 and 8 with the inner faces of the guide rails 7 and 8 being guides, by driving means to exert the function of holding or delivering the screen 5a or 5b. The carrier 9 runs in the direction indicated by the arrow at the automatic screen exchange operation.
For example, the guide rails 7 and 8 have a ]-shaped section, and a plurality of screen carriers 9 are moved and stopped with the inner faces of the guide rails being the guides; by driving means such as a roller chain, a long belt, a roplor a self-running single motor. The carrier 9 is stopped at a predetermined position and is moved from this predetermined position to an optional position. This combination of the guide rail and carrier is known, and any of known combinations can be optionally attained. The number of carriers mounted on the guide rail is appropriately determined in view of the adaptability to the screen exchange operation. For example, in view of the operation efficiency, it is preferred that such an arrangement be adopted that when one carrier is located at the screen exchange position, that is, the operating position of the screen transfer means 10, another carrier is located at the screen washing and drying means 11 and still another carrier is located at the screen dropping means 12-2. Of course, another carrier may be interposed between two of the foregoing carriers.
A plurality of screen carriers (hereinafter referred to as "carriers") 9 move along the guide rails 7 and 8. Since each guide rail consists of a pair of rails, a running part such as a pulley and a screen-holding part are arranged as a pair at corresponding positions of the paired rails, respectively. Accordingly, the carrier 9 can hold and deliver the screen freely releasably.
The screen transfer means 10 is automatically moved and stopped along the lower guide rail 7 and exerts the function of automatically transferring the screen 5 between the automatic screen printing machine 1-1 or 1-2 and the screen carrier 9.
A instance of the flat type screen transfer means 10 comprises a vertically expanding and contracting mechanism 10-1 supported by the going guide rail 7 below the rail 7, a horizontally expanding and contracting mechanism 10-2 attached to the vertically expanding and contracting mechanism 10-1 to expand and contract in the horizontal direction, and a horizontally movable screen-holding arm 10-3 attached to the horizontally expanding and contracting mechanism 10-2. The horizontally expanding and contracting mechanism 10-2 is capable of expansion and contraction in the horizontal direction and can reciprocate the arm 10-3 between the position above the printing machine 1-1 (1-2) and the position below the guide rail 7. The vertically expanding and contracting mechanism 10-1 is capable of expansion and contraction in the vertical direction and can move the screen between the position of the flat screen 5a of the printing machine 1-1 or 1-2 and the carrier 9 in co-operation with the horizontally expanding and contracting mechanism 10-2.
At the transfer of the screen, the vertically expanding and contracting mechanism 10-1 expands to drop the horizontally expanding and contracting mechanism 10-2 to the height of the screen of the printing machine 1-1 or 1-2, and the arm 10-3 built in the horizontally expanding and contracting mechanism 10-2 is elongated toward printing machine 1-1 or 1-2 to effect the delivery of the used screen 5a. Then, the horizontally expanding and contacting means 10-2 and vertically expanding and contracting mechanism 10-1 are returned to the original state to move the screen to the center between the rails, and the screen is raised and transferred to the carrier 9, and the screen is held by the carrier 9.
When the screen 5a or 5b held by the carrier 9 moving along the going lower guide rail 7 is transferred to the printing machine 1-1 or 1-2, the screen is delivered to a predetermined position of the printing machine 1-1 or 1-2 according to procedures reverse to the procedures mentioned above.
An instance of the rotary type screen transfer means 10 comprises a horizontally expanding and contracting mechanism 10-a supported by the going guide rail 7 below the guide rail 7, and a vertically expanding and contracting screen-holding mechanism 10-b attached to the horizontally expanding and contracting mechanism 10-a. The horizontally expanding and contracting mechanism 10-a is capable of expanding and contracting in the horizontal direction and reciprocating above the printing machine 1-1 (1-2) and below the guide rail 7. The screen-holding mechanism 10-b is capable of expanding and contracting in the vertical direction and holding and releasing the rotary screen and also capable of moving between the horizontally expanding and contracting mechanism 10-a and the rotary type screen 5b of the printing machine 1-1 or 1-2 and moving between the horizontally expanding and contracting mechanism 10-a and the screen carrier 9. When the rotary type screen is set, the screen is received from the screen carrier by the holding mechanism 10-b, the horizontally expanding and contracting mechanism 10-a is moved onto the printing machine 1-1 (1-2), the holding mechanism 10-b is then dropped to the setting height of the rotary type screen and the rotary type screen is attached at a predetermined position. When the rotary type screen is taken out, the rotary type screen is held by the holding mechanism 10-b brought down to the setting height of the rotary type screen, and the rotary type screen is transferred to the carrier 9 according to procedures revers to the above-mentioned procedures.
The screen transfer means (hereinafter referred to as "transfer means") 10 can be intermittently moved and stopped in correspondence to the set space P1, P2 or P (Fig. 1-A or 1-B) of the screen 5a or 5b of the printing machine 1-1 or 1-2. The transfer means 10 can move synchronously with the carrier 9 and is automatically returned to a predetermined position along the lower going guide rail 7 by a return mechanism.
The screen washing and drying means 11 exerts the function of washing and drying the used screen 5a, 5b held and delivered by the carrier 9. This screen washing and drying means (hereinafter referred to as "washing means") 11 comprises a washing zone 11-1 and a drying zone 11-2 and exerts the function of continuously and automatically washing and drying screens 5a or 5b, which have been used for the printing operation and is held and delivered by the carriers 9, while rotating screens in case of rotary type screens. In the washing zone, shower scattering of washing water and washing by a rotary brush are generally conducted, and in the drying zone, drying by blowing of hot air maintained at a relatively low temperature is generally adopted, though these operations are not illustrated in detail in the drawings.
The screen raising means 12-1 exerts the function of raising the screen 5a or 5b delivered from the washing and drying means 11 held by the carrier 9 and delivering the screen 5a or 5b together with the carrier 9 to the upper coming guide rail 8.
The screen dropping means 12-2 exerts the function of dropping the screen 5a or 5b delivered by the upper coming guide rail 8 and held by the carrier 9 and delivering the screen 5a or 5b together with the carrier 9 to the lower going guide rail 7, the function of delivering the screen to a predetermined screen-storing rack of the screen-storing rack means 13, and the function of taking out the screen 5a or 5b from the predetermined storing rack 14 and delivering the screen to the lower going guide rail 7.
The screen raising means (hereinafter referred to as "raising means") 12-1 and the screen dropping means (hereinafter referred to as "dropping means") may be lifts operated by a hydraulic pressure or pneumatic pressure, or conveyor devices moving in the vertical direction. There raising means and dropping means are disposed and used at both the end portions of the going and coming guide rails 7 and 8. The positions of these means are controlled by limit switches or the like. The screen 5a or 5b, which has been delivered to the right in the direction indicated by the arrow in Fig. 2-A or 2-B along the lower going guide rail 7 and has passed through the washing means 11, and the carrier 9 holding the screen are raised up to the same height as that of the upper coming guide rail 8 by the raising means 12-1 shown on the right end of Fig. 2-A or 2-B. The raised screen 5a or 5b and the carrier 9 holding the screen is delivered to the left in the direction indicated by the arrow in Fig. 2-A or 2-B along the upper coming guide rail 8, and the screen is thus carried to the dropping means 12-2 shown on the left end of Fig. 2-A or 2-B, and the screen 5a or 5b and the carrier 9 are dropped to the position of the same height as that of the lower going guide rail 7.
The screen-storing rack means 13 has a plurality of screen racks 14 built therein and exerts the function of storing and taking out required screens 5a or 5b.
Referring to Figs, 2-A and 2-B, the screen-storing rack means (hereinafter referred to as "storing rack means") 13 is arranged in the left end portion of the drawings, and a plurality of storing racks 14 are disposed in the interior of the storing rack means 13. Used screens or new pattern screens to be used are stored in these racks 14 one by one according to the arrangement order of the printing machines. By the cooperation with the above-mentioned dropping means 12-2 or by manual operation, used screens 5a or 5b are stored or new pattern screens are taken out.
When the present invention is applied to rotary type screens, since the rotary type screens have a cylindrical shape, a broad planar space as required in case of flat type screens is not necessary.
Accordingly, lattice racks are ordinarily used for the rotary type screens. In view of the space and easy handling it is preferred that the direction of storing and taking out the screens be in parallel to the direction of the advance of the carriers, as shown in the drawings. In the embodiment shown in the drawings, for realizing this feature, the length of the dropping means 12-2 is made slightly larger than the rotary type screen 5b, and turning means 15 is arranged above and below the dropping means. By the turning operation of the means 15, the direction of the rotary type screen 5b, which has been orthogonal to the direction of the advance of the printing machine, is changed to the direction parallel to the above-mentioned advance direction, and the rotary type screen 5b is stored at the position of the predetermined storing rack by the movement of the means 15. The rotary type screen may be stored or taken out at the position of the upper guide rail 8 or at the position of the lower guide rail, or the rotary type screen can be stored or taken out at an intermediate position between these two positions.
In the embodiment illustrated in the drawings, the going guide rail is disposed below and the coming guide rail is disposed above, but this arrangement can be reversed. Namely, there can be adopted a modification in which the going guide rail is disposed above and the coming guide rail is disposed below.
The screen exchange apparatus of the present invention comprises the above-mentioned members. These members can be manually driven or mechanically driven, or they can be driven by using a hydraulic pressure circuit or an electric circuit. Of course, the driving of the respective members can be automated with the aid of a computer or sequencer, and the operations of exchanging, washing, drying, storing and taking out screens can be automatically performed according to the operating and working cycle of the automatic screen printing machine.
According to the present invention, the respective operations of the printing process can be performed according to the following procedures.

(I) Case where printing is carried out with one printing pattern but the color is changed:

A used screen is taken out from the printing machine, and the screen is washed, dried and returned to the same position of the printing machine again.
In this case, the used screen 5a or 5b is taken out from the printing machine 1-1 or 1-2, and after washing and drying, the screen should be returned to the same position of the printing machine. Therefore, according to a preliminarily inputted control program, the transfer means 10 is moved along the lower going guide rail, and the means 10 is stopped at the position of the arrangement space P1 or P2 of screens 5a shown in Fig. 1-A in case of flat type screens, or at the position of the arrangement space P of screens 5b in case of rotary type screens. In case of flat type screens, simultaneously with the stop of the means 10, by the vertically expanding and contracting mechanism 10-1, the horizontally expanding and contracting mechanism 10-2 is dropped to the same level as that of the screen on the printing machine, and the arm 10-3 built in the mechanism 10-2 is elongated toward the printing machine 1-1 or 1-2 to receive the used screen 5a. In case of rotary type screens, simultaneously with the stop of the means 10, the horizontally expanding and contracting mechanism 10-a expands onto the printing machine and the screen-holding means 10-b is dropped to the same level as that of the screen on the printing machine to receive the used screen 5b.
The transfer of the flat type screen 5a to the arm 10-3 from the printing machine or the transfer of the rotary type screen 5b to the screen-holding mechanism 10-b from the printing machine is ideally accomplished by a robot handle, but no particular disadvantage is brought about if this transfer is manually performed.
The screen 5a or 5b thus transferred to the arm 10-3 or the screen-holding mechanism 10-b is received at the center of the lower going guide rail 7 by the horizontally expanding and contracting mechanism 10-2 and the vertically expanding and contacting mechanism 10-1, and the screen is raised up and is then delivered to the carrier 9 and held thereby. The screen 5a or 5b held by the carrier 9 is moved in the direction indicated by the arrow shown in Fig. 2-A or 2-B along the lower going guide rail 7, washed and dried by the washing means 11, and circulated through the raising means 12-1, the upper coming guide rail 8 and the dropping means 12 and moved in the direction of the arrow along the lower going guide rail 7 again.
In this case, since the transfer means 10 is stopped according to the screen arrangement space P1 or P2 (Fig. 1-A) or P (Fig. 1-B) on the printing machine, the carrier 9 is temporarily stopped at the same position synchronously with the transfer means 10, and by the operation reverse to the above operation, the screen 5a or 5b is transferred to the transfer means 10 from the carrier 9. In the transfer means 10 which has received the screen 5a or 5b, the vertically expanding and contracting mechanism 10-1, the vertically expanding and contracting mechanism 10-2 and the arm 10-3 in case of flat type screens or the horizontally expanding and contracting mechanism 10-1 and the screen-holding mechanism 10-b in case of rotary type screens perform operations reverse to the above-mentioned operations, whereby the screen 5a or 5b is returned to the printing. position of the printing machine 1-1 or 1-2.
The foregoing operations are continuously repeated with respect to many screens corresponding to the number of colors to be printed in the automatic screen printing machine, and the screen 5a or 5b which has been used for printing of one color is taken out, washed and dried and is automatically returned to the original position again. Thus, the preparation for printing of the next color is completed.

(II) Case where printing of all of colors with the same pattern is completed:

The used screen taken out from the printing machine is washed, dried and stored in the storing rack means.
In this case, after termination of printing of the final color, the screen 5a or 5b is treated in the same manner as described in (I) above, but the screen need not be returned to the printing machine.
Accordingly, the screen 5a or 5b is delivered in the direction indicated by the arrow in Fig. 2-A or 2-B through the lower guide rail 7, the washing and drying means 11, the raising means 12-1 and the upper guide rail 8 by the carrier 9 and is conveyed to the dropping means 12-2 located on the right side in the drawings. In this case, however, since the screen 5a or 5b has been washed and dried after completion of printing all the colors, the screen 5a or 5b is stored in an appropriate store rack 14 of the storing rack means by the dropping means 12-2.
In this case, there can be adopted a method in which the screens are transferred one by one from the carriers 9 to the racks 14, and the storing racks 14 are raised or dropped one by one as the screens are stored, whereby all of the screens are stored.

(III) Case where printing is started with a new pattern screen:

A screen is taken out from the storing rack means and is delivered to a predetermined position of this printing machine.
In this case, new pattern screens 5a or 5b are stored and arranged in the storing rack means 13 according to the arrangement order of screens in the printing machine 1-1 or 1-2. The screens 5a or 5b are taken out one by one in this order from the storing racks 14 by the dropping means 12-2, or the storing racks 14 are raised or dropped one by one and the screens are pushed out one by one at the height of the lower going guide rail 7, delivered to carriers 9 and gripped thereby.
The transfer means 10 supported below the lower guide rail 7 is moved and stopped according to the predetermined screen arrangement space P1 or P2 (Fig.1-A) or P (Fig. 1-B) of the printing machine 1-1 or 1-2. Synchronously with this moving and stopping of the transfer means 10, the carrier 9 is moved in the direction of the arrow and is temporarily stopped to deliver the screen 5a or 5b to the transfer means 10. The transfer means 10 receives the screen 5a or 5b, and according to the same procedures as described in (I) above, the screen 5a or 5b is transferred to the printing machine 1-1 or 1-2.
In the above-mentioned manner, new pattern screens stored in the storing rack means 13 are automatically arranged in the printing machine 1-1 or 1-2 according to the predetermined order, and the preparation for printing of a new pattern is completed. Changes of colors in these screens are accomplished by the same operations as described in (I) above.
As pointed out hereinbefore, according to the apparatus of the present invention, screens can be automatically exchanged at a high efficiency according to a predetermining printing program when (1) colors are changed with the same pattern, (2) printing of all colors with one pattern is completed, or (3) printing is started with new pattern screens. However, it sometimes happens that a relatively long time is required for washing and drying used screens because of the capacity of the washing and drying means, and in this case, if one kind of screens is used, the apparatus of the present invention cannot be worked at a high efficiency.
In the case where a long time is required for washing and drying, as shown in Fig. 4-A and 4-B, a residence device 20 for temporarily stocking screens therein before entrance of the screens 5c into the washing and drying means 11 is disposed so that a plurality of kinds of screens are treated by the apparatus of the present invention.
More specifically, referring to Figs. 4-A and 4-B, the used screen 5c is temporarily stocked in the residence device 20 before the screen 5c is introduced into the washing and drying means. Immediately, a screen of a subsequent pattern is arranged on the printing machine and printing of a first color is started. During this printing, the used screen 5c stocked in the residence device 20 is washed and dried by a washing machine 11-1 and a drier 11-2, and the washed screen 5d is stored in the rack 13. Similarly, a screen of a second pattern is stocked in the residence device 20 and washed and dried by the washing machine 11 and drier 11-2 while the printing operation is conducted with another screen. In the embodiment shown in the drawings, two kinds of screens are used, but the number of kinds of screens is not limited to 2, and at least three kinds of screens can be easily treated by changing the printing program or the like.
If this residence device 20 is disposed, while printing is conducted with screens of one pattern, other screens can be washed and dried gradually over a long period, and washing and drying devices having a high capacity need not be used.
The automatic screen exchange apparatus of the present invention is arranged in parallel to an automatic printing machine and comprises the above-mentioned members, that is, (1) guide rails, (2) screen carriers, (3) screen transfer means, (4) screen washing means, (5) screen raising and dropping means and (6) screen-storing rack means. Since these members are arranged in specific order so that screens pass through these members, operations of exchanging, washing, drying stocking and taking out screens can be performed at a high efficiency with any loss of time according to the operating and working cycle of the automatic screen printing machine. Therefore, various operations as described below during the printing process can be performed at a high efficiency according to the operating program of the printing machine:

(1) in the case where the color is changed at the printing with one pattern, the operations of taking out the used screen from the printing machine, washing and drying the used screen and returning the washed screen to the same position in the printing machine;
(2) in the case where printing of all of colors with one pattern is completed, the operations of taking out the used screen from the printing machine, washing and drying the screen and storing the washed screen in the storing rack means;
(3) in the case where printing is started with a new pattern screen, the operations of taking out the screen from the storing rack means, and delivering the screen to a predetermined arrangement position of the printing machine; and
(4) in the case where the color is changed in screens of a plurality of patterns, the operations of performing washing and drying of screens and printing alternately.

As is apparent from the foregoing description, in the automatic screen exchange apparatus of the present invention, the operations required for exchanging and washing screens in the printing process of an automatic screen printing machine are automatically carried out. Therefore, the working efficiency of the printing machine can be highly improved and rationalization (reduction of labor, time, energy and cost) can be attained.

Claims

A screen exchange apparatus in an automatic screen printing machine, (1-1, 1-2), comprising:
a plurality of going and coming guide rails (7, 8) disposed in parallel to the automatic screen printing machine (1-1, 1-2) to effect reciprocating delivery of screens (5a, 5b);
a plurality of screen carriers (9) for holding and delivering screens (5a, 5b) along said guide rails (7, 8);
screen transfer means (10) capable of moving and stopping along the going guide rails (7) to effect transfer of screens (5a, 5b) between the automatic screen printing machine (1-1, 1-2) and the screen carriers (9);
screen raising and dropping means (12-1, 12-2) disposed between front and rear ends of the guide rails (7, 8) to raise the screen carriers (9) from the going guide rails (7) to the coming guide rails (8) and drop the screen carriers (9) from the coming guide rails (8) to the going guide rails (7);
screen washing and drying means (11) disposed in the vicintiy of the terminal end portion of the going guide rails (7) to wash and dry used screens (5a, 5b) held and delivered by the screen carriers (9); and
screen-storing rack means (13) comprising a pluraliy of screen-storing racks (14) disposed at the starting end portion of the going guide rails (7) to effect necessary storing and take-out of screens(5a, 5b).
A screen exchange apparatus as set forth in claim 1, wherein the screen is a flat type screen (5a) comprising a screen proper and a screen frame.
A screen exchange apparatus as set forth in claim 1, wherein the screen is a rotary type screen (5b).
A screen exchange apparatus as set forth in claim 3, wherein a rotary driving mechanism for revolving the rotary type screen (5b) is mounted on the screen carrier (9).
A screen exchange apparatus as set forth in claim 1, wherein a residence device (20) for temporarily stocking the screen (5a, 5b) before washing is arranged on the screen washing and drying means (11).