Abstract: A stencil stretcher frame unit includes a stencil stretcher frame for stretching a printing stencil, the stencil stretcher frame including a seat; a protective device accommodated in the seat and holding the stencil stretcher frame, the protective device including a plurality of protective bars configured to hold the printing stencil in a plane and to accommodate a circumferential edge of the printing stencil so as to cover the circumferential edge along a circumference of the printing stencil, adjacent ones of the plurality of protective bars being supported on each other at respective end areas of the protective bars so as to allow a relative movement with respect to each other; and a joining device configured to fasten the protective device to the stencil stretcher frame.

Abstract: A stencil stretcher frame unit includes a stencil stretcher frame for stretching a printing stencil, the stencil stretcher frame including a seat; a protective device accommodated in the seat and holding the stencil stretcher frame, the protective device including a plurality of protective bars configured to hold the printing stencil in a plane and to accommodate a circumferential edge of the printing stencil so as to cover the circumferential edge along a circumference of the printing stencil, adjacent ones of the plurality of protective bars being supported on each other at respective end areas of the protective bars so as to allow a relative movement with respect to each other; and a joining device configured to fasten the protective device to the stencil stretcher frame.

Abstract: A stencil stretcher frame unit comprises a stencil stretcher frame for stretching a printing stencil, the stencil stretcher frame including a seat; a protective device accommodated in the seat and holding the stencil stretcher frame, the protective device including a plurality of protective bars configured to hold the printing stencil in a plane and to accommodate a circumferential edge of the printing stencil so as to cover the circumferential edge along a circumference of the printing stencil, adjacent ones of the plurality of protective bars being supported on each other at respective end areas of the protective bars so as to allow a relative movement with respect to each other; and a joining device configured to fasten the protective device to the stencil stretcher frame.

Abstract: A stencil stretcher frame unit comprises a stencil stretcher frame for stretching a printing stencil, the stencil stretcher frame including a seat; a protective device accommodated in the seat and holding the stencil stretcher frame, the protective device including a plurality of protective bars configured to hold the printing stencil in a plane and to accommodate a circumferential edge of the printing stencil so as to cover the circumferential edge along a circumference of the printing stencil, adjacent ones of the plurality of protective bars being supported on each other at respective end areas of the protective bars so as to allow a relative movement with respect to each other; and a joining device configured to fasten the protective device to the stencil stretcher frame.

Abstract: A protective device with a frame includes protective bars for holding a printing stencil in a plane and joining means for fastening to a stencil stretcher frame, whereby the protective bars accommodate the edge of the printing stencil along its circumference in a manner that covers the edge. In addition, a stencil stretcher frame is provided for stretching a printing stencil held in a such protective device Adjacent protective bars, while forming the frame, are supported on each other with one of their respective end areas in a manner that allows a relative movement with respect to each other. For the stencil stretcher frame, a seat for accommodating the protective device and a joining means for fastening the protective device are provided.

Abstract: The invention relates to a tool holder 1 for a rotating tool, especially a drilling head and/or milling head, comprising a drive shaft 4 that can be connected to a drive motor and a collet chuck 2 that is non-rotatably connected to the drive shaft 4 in order to hold the tool, whereby the drive shaft 4 and the collet chuck 2 are positively connected by means of a coupling element 5 for purposes of transmitting torque. In order to securely hold the tool and to concurrently have a simple construction of the tool holder 1, it is proposed for the coupling element 5 to be axially displaceable relative to the collet chuck 2 so as to release the tool.

Abstract: A tool holder for a rotating tool, especially a drilling head and/or milling head, includes a drive shaft that can be connected to a drive motor and a collet chuck that is non-rotatably connected to the drive shaft in order to hold the tool. The drive shaft and the collet chuck are positively connected by means of a coupling element for purposes of transmitting torque. In order to securely hold the tool and to concurrently have a simple construction of the tool holder the coupling element may be axially displaceable relative to the collet chuck so as to release the tool.

Abstract: A protective device with a frame includes protective bars for holding a printing stencil in a plane and joining means for fastening to a stencil stretcher frame, whereby the protective bars accommodate the edge of the printing stencil along its circumference in a manner that covers the edge. In addition, a stencil stretcher frame is provided for stretching a printing stencil held in a such protective device. Adjacent protective bars, while forming the frame are supported on each other with one of their respective end areas in a manner that allows a relative movement with respect to each other. For the stencil stretcher frame, a seat for accommodating the protective device and a joining means for fastening the protective device are provided.

Abstract: A drilling or milling head, especially for printed circuit board milling machines and/or engraving machines, having a collet chuck (11) which can be actuated by a rapid change mechanism and which is driven by a transmission. The collet chuck is opened by an axial displacement relative to a clamping sleeve (50), with the force necessary for the displacement being transmitted via a friction clutch. The transmission includes a ball bearing (9) whose balls (12) are moved around a common axis in a concentric manner by a driving part (6) fixed on a motor drive shaft (5). In addition, the balls are mounted between two bearing surfaces (13, 14) which are aligned in a concentric manner with regard to the axis and which have a circular cross-section. The balls are at least partially engaged with the bearing surfaces in a positive manner.

Abstract: A drill or milling head (1), especially for printed circuit milling machines and engraving machines, including a collet chuck (27) which can be actuated by a rapid change mechanism. The drill or milling head includes a drive shaft which can be connected to a motor (3a). The collet chuck (27) is opened by axial displacement opposite a clamping sleeve (29), and the force necessary for the axial displacement is transmitted via a friction clutch (19, 23). As a result the drill or milling head cannot be damaged, and there is no danger of injury when changing the tool if the user fails to turn the motor (3a) off beforehand.

Abstract: A tensioning frame (1) for stencils (9) formed of metal foils or plastic films, especially for stencil printing, provided at their margins (8) with perforations (10) for tensioning. The frame includes a tensioning device operated by a pressure medium for driving tensioning bars (5) that carry hooking pins (6) that engage the perforations of the stencil. The tensioning device is formed by an elastically deformable tensioning tube (4) disposed in a frame profile (2) and uniformly supplied with a pressure medium. The tensioning bars lie with the full length of their front sides in contact with the tensioning tube and with their back sides resting against fulcrum nubs (17) which in turn are supported against an extrusion (3) which closes the frame profile. The tensioning bars can be pivoted by inflating and expanding the tensioning tubes to stretch the stencil over a bridge (16) on the frame.

Abstract: The invention relates to a clamping-stretching system for stencils for screen printers, with a printing table for PC boards designed for applying colors, pastes, adhesives, etc., onto even surfaces of a print, preferably onto electronic PC boards with a stencil, which also allows through plating of holes of electronic PC boards. The clamping-stretching system of the stencil may be an element of a machine, or it may be fixed via a frame (4) to all types of printers. Stencils are clamped into it in an exchangable manner. A front crossbar (9) and a back crossbar (10) are guided in the side profiles of the frame which have a pressure bar at their lower part. The front crossbar (9) rests against the front wall (7) or aganist the front profile of the frame via at least one adjustment screw (5) and a cascade of disk springs (13).

Abstract: A rotary slide valve (1) for selective delivery of pressurized air or vacuum to an apparatus (3), which permits a very precise delivery of vacuum or pressurized air through a control port (2), especially to a plenum (16) of an apparatus (3) for introducing a conductive paste into holes (22) in circuit boards (17). Two transfer passages (10 and 11) are disposed in a rotary slide (9) offset by 120.degree. around the axis of rotation, and transfer ducts (12, 13 and 14) contiguous with the rotary slide and communicating with the control port (2) and with inlet/outlet ports (7 and 8) are arranged in a reference plane likewise offset by 120.degree. around the axis of rotation.