Hand grinder and valve therefore

Abstract

To be able to control the admission of compressed air or liquid to a machine in a hand tool, the working medium can be admitted to the machine through a handle with a built-in valve. By turning the handle (1) the valve opens or closes. The valve body itself (7,9) is secured to a stay in the form of a bolt (10) and a pipe (8) screwed into the bottom of the handle casing (1), whereas the valve seat (14) is formed as a recess in a bushing (2) being stationary relative to the casing. The handle has an oblique track (4) wherein a bolt (3) secured in the bushing moves the casing (1) and thereby the valve body relative to the bushing (2) when the handle is turned. When the handle is released in the open position of the valve (FIG. 3), the pressure exerted by the medium will move the casing so as to close the valve since the area of the casing is larger than that of the bush (2). The machine can thereby be safely and reliably disconnected by releasing the hold on the handle. The valve can be used for a hand grinder with a U-shaped handle pipe with handle ends and a hollow spindle situated between the handle ends, an air machine being arranged in the spindle. The spindle has a number of slotted grinding discs, and a pressure medium is admitted to the machine through passages in the handle pipe. A simple and reliable hand grinder which can efficiently grind deep profiles is thereby obtained.

I claim: 
     
       1. Hand grinder, characterized in that the hand grinder comprises a substantially U-shaped handle pipe (17) having an inlet and an outlet passage (18,19) for a pressure medium used for operating a motor (20), said inlet passage (18) being adapted to supply the pressure medium from a valve (21) to the machine (20), said outlet passage (19) being adapted to carry the pressure medium from the motor (20) to an outlet opening (23) on the handle pipe (17) the ends thereof being designed as handles (25,26), said valve (21) being mounted in one of the handles (25) of the handle pipe (17), and that the motor (20) drives a rotating spindle (27) having a grinding means. 
     
     
       2. Hand grinder according to claim 1, characterized in that the axis of rotation of the spindle (27) is substantially parallel to the longitudinal axes of the handles (25,26). 
     
     
       3. Hand grinder according to claims 1, characterized in that the spindle (27) is hollow, and that the motor (20) is built into the spindle (27). 
     
     
       4. Hand grinder according to claims 1, characterized in that the hand grinder is provided with a safety guard (30) secured to a connecting part of the handle pipe (17), said guard (30) covering at least the rear part of the grinding means. 
     
     
       5. Hand grinder according to claims 1, characterized in that the grinding means (28) comprises a plurality of circular slotted grinding discs (28) fixed co-axially around a spindle and secured by retaining discs (31). 
     
     
       6. A valve comprising a displaceable valve body which can abut a valve seat and limit the flow of a medium,   a valve casing (1) closed at one end and having an inlet for the medium at said end,   a stem (8, 10) extending from the closed end of the casing end being provided with the valve body (5, 9) at the free end,   a bushing having one end movably mounted in the open end of the casing receiving the stem for axial displacement therein, and   a recess formed in the other end of the bushing to define the valve seat whereby said valve body faces the end of the casing and co-operates with the valve seat.   
     
     
       7. Valve according to claim 6, characterized in that the casing (1) has an inner end surface which is larger than an area formed by the bushing (2) opposite the end surface of the casing. 
     
     
       8. Valve according to claim 6, characterized in that said casing (1) is rotatable about the bush (2). 
     
     
       9. Valve according to claims 8, characterized in that the casing (1) is provided with a track (4) forming an angle with the axis of rotation of the casing, and that a pin (3) secured to the bush (2) moves in the track. 
     
     
       10. Valve according to claim 6, characterized in that the stem comprises a bolt (10) having a head and being screwed into the end of the casing, and retaining behind said head a ring (7) with a packing (9) and a spacing pipe (8). 
     
     
       11. Valve according to claims 6, characterized in that the bush (2) at an end facing away from the end of the casing (1) is secured to an admission hose or pipe (5) for said medium in the bush.