US3585930A

US3585930A - Device on rotary screen printing machines

Info

Publication number: US3585930A
Application number: US761466A
Authority: US
Inventors: Walter Bohm
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-09-27
Filing date: 1968-09-23
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22
Also published as: CH475847A; DE6609048U; NL6813778A; DE1786330B2; DE1786330A1; DE1786330C3; AT291309B; FR1583359A

Abstract

A device on rotary screen printing machines for longitudinally tensioning the rotary screens. The screen holders of at least one machine side being adjustable in parallel to the rotary screen axis wherein an adjustable device for the movable screens is provided. The adjustable device comprising stopping means, the stopping means limiting the movement of the screen holder to a predetermined extent upon release.

Description

United States Patent [56] References Cited UNITED STATES PATENTS 10/1958 Leibenguth [72] Inventor WalterBolun Klrchbichl No. 143, Tyrol, Austria [21] AppLNo. 761,466

101/1271 l0l/l27.1 101/1271X 2,854,922- 3,39l,635 7/1968 Matheus...... 3,404,623 10/1968 Watkin..............,..l.......

[22] Filed Sept. 23, 1968 [45] Patented June 22, 1971 [32] Priority Sept. 27, 1967 1 1 FQll l IliiN PATENTS Canada Primary Examiner- Robert E. Pulfrey Assistant Examiner-Alan E. Kopecki Auamey- Wenderoth, Lind & Ponack Austria A 8757 ABSTRACTrA device on rotary screen longitudinally tensioning the rota m m R P. N E E R w m. n r A g T .m 0 w R n NSD 0W3, E15 m m vm E DM4 M D Km s .mmm hma u m i hh .m t .m n mm. ed a c 500 m In ders of at least one machine side b th e rotary sc'reen axis wherein an adjustable device for the movable screens is provided. The adjustable device comprising stopping means, the stopping means limiting the movement of the screen holder to a predetermined extent upon release.

PATENTEU JUH22 I57;

SHEEI 1 [IF 2 Fig. I

WALTER BOUM HMM X a! P ATTORNEY f5 PATENTED JUHZZ 19?:

SHEET 2 BF 2 WALTER 130] IM,

INVENTOR BYHJJIAM.ZLJ

ATTORNEY s DEVICE N ROTARY SCREEN PRINTING MACHINES This invention relates to a device on rotary screen printing machines for longitudinally tensioning rotary screens, the screen holders of at least one machine side being adjustable in parallel to the rotary screen axis.

In order to ensure a correct working of screen printing rotary screens, the gauze or screen cylinder consisting of flexible material of the rotary screen has to be tensioned in longitudinal direction, i.e. in axial direction of the rotary screen. A possibility of longitudinally tensioning the rotary screens consists in that the frontal screen endpieces are axially supported in the screen holders and that the tensioning and releasing take place by adjusting at least one of the screen holders on both sides in parallel to the rotary screen axis. There is the risk that upon releasing, i.e. upon replacing the screen holder in direction of the screen width, the screen holders are adjusted to a too large extent so that the screen cylinder is jolted and therefore destroyed.

This shortcoming is avoided in that a means for limiting the movement of the screen holder is incorporated in the adjusting device of the movable screen holder through which the movement of the screen holder is limited to a predetermined extent upon releasing.

An embodiment of the invention is hereinafter described with reference to the accompanying drawing'without being limited to it.

FIG. I is a schematic and diagrammatic view of a screen holder of a rotary screen printing machine. FIG. I also represents a circuit diagram.

FIG. 2 shows a detail of this circuit diagram.

FIG. 3 shows a section of an enlarged detail of FIG. 1.

One endpiece 2 of the rotary screen I is arranged in the screen holder 3 of one machine side. The screen holder 3 is adjustable in parallel to the rotary screen axis by means of the two threaded spindles 4 whose threads are in mesh with corresponding nut thread elements (not shown in the drawing) in the screen holder 3. The threaded spindles 4 are driven by the shaft 5 which is driven by a motor M (shown in symbol). Upon adjusting the screen holder 3 in direction S the rotary screen 1 is tensioned, the endpiece 2 of the rotary screen I being axially supported by its disc 2 0n the parts 3' of the screen holder 3. Upon releasing, the screen holder 3 is adjusted in direction E.

The shaft 5 has the form of a screw 6 in the middle which works together with a spiral wheel 7. A switching element 8 is arranged on the elongated shaft 7 of the spiral wheel or worm gear 7. The switching element 8 is connected with the shaft 7' by a slipping connection, e.g. by a fit or by an adjustable slipping clutch (Figure 3). Upon rotation of the shaft 7' the switching element is taken along up to a firm stop. This is the case upon tensioning the rotary screen 1 in direction S, the switching element 8 first rotating with the shaft 7, but being stopped on the stop 9, whereas the shaft 7 of the spiral wheel can continue its rotation.

Upon releasing the rotary screen 1 in direction E the shaft 7 of the spiral wheel rotates in the other direction and takes along the switching element 8 which is now removed from the stop 9 and rotates into the dash-lined position. At the end of this movement the switching element 8 pushes against the pushbutton 10 of the limit switch 10; this is possible since the resistance the pushbutton l0 opposed to the pressing is smaller than the pulling moment of rotation conditioned by the fit or slipping clutch between the shaft 7' and the pushbutton 8. Owing to the pressing of the pushbutton 8 the current supply to the motor M is interrupted, which stops the drive of the shaft 5 and the movement of the screen holder 3 in direction E. Thus the limit of the movement of the screen holder 3 is obtained upon release (direction E).

Figure 1 also shows a possible switching of the motor M. By actuating the switch 11 in direction S the motor M is set into movement in direction S for tensioning the rotary screen 1, and by actuating the switch 11 III direction E for releasing or slackening the rotary screen in direction E. In the latter case the current is supplied to the motor M through the limit switch l0-see FIG. 2 and is interrupted, as described, if the switching element 8 pushes the pushbutton 10' of the limit switch 10.

The firm stop 9 is an eccentric piece and can be rotated in adjustable manner; thus the field of traverse of the switching element 8 and the extent of the limit of the movement of the screen holder 3 can be adjusted upon release.

FIG. of a slipping clutch between the shaft 7' and the switching element 8 can be seen in FIG. 3. On the shaft 7 which carries the spiral wheel or worm gear 7 in mesh with the screw 6, a jacket element 13 provided with a circular flange 12 is arranged, not capable of rotation. The switch element 8 seated on the element 13 is pressed against the circular flange 12 by means of the spring 14. Thus a frictional connection between the switching element 8 and the circular flange 12 is produced owing to which the switching element is taken along upon rotating shaft 7 and rotating element 13 until the switching element 8 is taken along by a firm stop (9 in FIG. 1).

What I claim is:

1. Apparatus on a rotary screen printing machine for longitudinally tensioning and slackening a rotary screen thereof comprising a machine frame, a pair of screen holders mounted on said frame, the ends of said rotary screen being supported by said screen holders, means connected to one of said screen holders to make it movable and adjustable in parallel to the screen axis to cause tensioning and slackening of the screen, a motor operatively connected to said movable screen holder and positively driven to cause movement thereof for tensioning and slackening the screen, and stopping means for limiting the movement of said movable screen holder to a predetermined extend upon slackening, said stopping means comprising a switching element with means supporting same and operatively connecting it with said motor to be moved thereby, and a limit switch electrically connected to said motor, said switching element being engageable with said limit switch upon slackening the screen to control said motor.

2. Apparatus as defined in claim 1 wherein the means for making said screen holder movable and adjustable include at least one shaft operatively connected to said motor and to said one holder so that said shaft is rotatable in the opposite directions to effect tensioning and slackening of the screen, said switching element being connected to said shaft by means of a slipping connection.

3. Apparatus as defined in claim 2 wherein a stop member is mounted externally of said shaft to engage the switching element as said element is moved in a direction away from said switch, thereby limiting the field of movement of said switching element, and said shaft of said switching element continues its rotation.

4. Apparatus as defined in claim 3 wherein said stop member is eccentrically pivotally mounted on a different shaft.