A grinding machine particularly for grinding the non-parallel opposite side faces of a lathe tool, having two grinding wheels arranged opposite one another across a movable work-piece table, and a work-piece support which is angularly adjustable to present opposite faces of a work-piece in turn to the respective grinding wheels.
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What I claim is
1. In a grinding machine having a table for supporting a workpiece and defining a path of travel for the workpiece during grinding, grinding wheel mounting means drivably mounting two grinding wheels one on each side of said path of travel, and workpiece mounting means on said table and including means for setting the angle which a face of the workpiece makes with a plane containing its direction of travel during grinding whereby one wheel may be caused to work on said workpiece before the other wheel works thereon, the improvement comprising: said grinding wheel mounting means being independent of one another and each said grinding wheel mounting means being separately positionably adjustable in three senses, viz:
2. A grinding machine as claimed in claim 1, including means for re-setting the said work-piece angle after the work-piece has been worked upon by one of said grinding wheels but before it is worked upon by the other grinding wheel.
3. A grinding machine as claimed in claim 2, wherein said re-setting means is operatively connected to the table drive means for actuation at a predetermined point in the travel of the work-piece.
4. A grinding machine as claimed in claim 2, wherein said workpiece holder is movable in opposite directions along said path, the said grinding wheel mounting means being arranged to mount the grinding wheels directly opposite one another across the said path of travel of a work-piece, and the said re-setting means is arranged to re-set the work-piece angle at the same time as its direction of movement is reversed at one end of its said path of travel.
5. A grinding machine as claimed in claim 2, wherein the said grinding wheel mounting means are arranged to mount the grinding wheels at positions spaced from one another along the said path of travel of a work-piece, and the said re-setting means is arranged to re-set the work-piece angle at a point in said path of travel between the two grinding wheels.
6. A grinding machine as claimed in claim 1, wherein the said work-piece mounting means comprises a fluid-operated rotary actuator.
This invention relates to grinding machines for use in forming or re-forming the surface of a work-piece.
It is sometimes necessary to grind two opposite faces of a work-piece so that their planes make a small angle with one another, one example being the opposite side faces of a tooth of a cutting tool which faces have to be under-cut or relieved to provide the necessary clearance angle relative to the cutting edge. Up to now such faces have been ground in two separate operations with the same grinding wheel, which of course necessitates reversing the position of the work-piece between the two operations. Such a procedure is inconvenient and time-consuming.
According to the present invention there is provided a grinding machine including a table for supporting a work-piece and defining a path of travel for the work-piece during grinding, means for drivably mounting two grinding wheels one on each side of said path of travel, and work-piece mounting means associated with or mountable on said table and including means for setting the angle which a face of the work-piece makes with a plane containing its direction of travel during grinding.
With such an arrangement two opposite faces of a work-piece may be ground at an angle to one another, one by each of said grinding wheels, without it being necessary to reverse the work-piece position but simply by re-setting the work-piece through the small angle between its faces between the two grinding operations. In a preferred form of the invention the grinding machine incorporates means for automatically carrying out such re-setting, which means may conveniently be linked to the table drive means. The resetting may be effected either in the course of the movement of a work-piece along its said path of travel in one direction (i.e. at a position between the two grinding wheels if they are mutually spaced along such path), or at one end of the path of travel if the grinding wheels are directly opposite one another and the direction of movement of the work-piece must therefore be reversed for operation on its second face.
Preferably the said mounting means for the grinding wheels are arranged to permit the rotational axes of the wheels to be angularly adjusted about axes perpendicular to the axis about which the work-piece is settable as aforesaid, so as to enable the work-piece faces to be ground at compound angles. The said work-piece mounting means may, as is presently preferred, comprise a so-called "rotary actuator" of known construction mounted on the table and itself carrying a mounting device for the work-piece; a hydraulically controlled rotary actuator is preferably employed which can be automatically controlled in conjunction with table movement. Alternatively a mechanism similar to such a rotary actuator and on which the work-piece is directly mountable could be built in as an integral part of the table.
A machine according to the invention may be arranged to mount two or more separate work-pieces in a row, in such manner that all of the work-pieces are first ground by one grinding wheel, then all angularly re-set, and then all ground by the other wheel.
Two embodiments of grinding machines in accordance with the invention will now be described by way of example and with reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a first embodiment of a grinding machine according to the invention, incorporating a rotary actuator for setting the angle of a work-piece;
FIG. 2 is a perspective view of the rotary actuator showing the internal components thereof;
FIGS. 3, 4 and 5 are respectively a side elevation, an end view and a plan view of part of a lathe cutting tool with a fully relieved cutting tip; and
FIG. 6 is a perspective view of the table of a second embodiment.
Referring to FIG. 1 of the drawings, there is shown a grinding machine 1 having a frame 30 upon which are pivotally mounted two 3 H.P. motors 2 and 2'. Each motor has a drive shaft 3 and 3' to which is attached a grinding wheel 4 and 4' respectively. The grinding wheels 4 and 4' can be inclined towards one another by rotating the respective motors 2 and 2' about their pivotal axes on frame 30. The distance between grinding wheels 4 and 4' can be varied by rotating hand wheels 5 and 5'. Similarly, the motors 2 and 2' can be raised or lowered by rotating hand wheels 6 and 6'.
An elongate table 7 is positioned below the grinding wheels 4 and 4' and supports a rotary actuator 8 in a T-slot 9. The table is drivable parallel to the length of the slot 9 so as to define a path of movement of a work-piece through the machine and between the wheels 4 and 4'. A holder 10 for mounting a work-piece 11 is mounted on rotary actuator 8.
When the drive for the table 7 is actuated the table carrying the rotary actuator 8 and the holder 10 move from left to right as viewed in FIG. 1. After the holder 10 passes grinding wheels 4 and 4' the direction of the drive is automatically reversed and the rotary actuator 8 and the holder 10 return to their initial position at which the drive stops.
Referring now to FIG. 2, the hydraulic rotary actuator 8 comprises two racks 12 and 13 formed on cylinders 14 and 15 respectively. The racks 12 and 13 engage a pinion 16 which is secured fast on a shaft 17. Hydraulic power lines 19 and 19' are connected to bores housing cylinders 14 and 15 respectively. When hydraulic liquid is pumped through line 19', rack 12 moves to the left as viewed in FIG. 2. Pinion 16 rotates anti-clockwise and rack 13 moves to the right. Similarly, when hydraulic liquid is pumped through line 19 into cylinder 15, rack 13 moves to the left and pinion 16 rotates clockwise. An end stop 18 is located adjacent one end of each cylinder and can be adjusted to limit the travel of racks 12 and 13.
Referring again to FIG. 1, holder 10 is mounted on shaft 17 and is pivotable about the longitudinal, vertically extending axis of shaft 17 denoted by line X--X. The end stops 18 are set so that holder 10 can move through the desired angle between the opposite faces of the work-piece, e.g. 6° arranged 3° to each side of a vertical plane containing the direction of table movement.
The drives for table 7 and for the hydraulic actuator 8 are interconnected so that whilst the table is moving from left to right as viewed in FIG. 1, the holder 10 is positioned about axis X--X to 3° to the right of the direction of table movement. This angles the work-piece 11 into engagement with grinding wheel 4'. As the holder 10 moves past grinding wheel 4', the wheel grinds the side of the work-piece 11 so that it tapers progressively from the leading edge 20. After the holder 10 has moved past grinding wheel 4' a switch (not shown) is tripped to reverse the direction of the drive and the table then travels from right to left. As the direction of the drive is reversed the flow of hydraulic liquid to rotary actuator 8 is reversed and holder 10 is rotated about axis X--X to 3° to the left of the direction of table movement. As the holder 10 passes grinding wheel 4, the wheel grinds the side of the work-piece 11 so that it is symetrically tapered about its longitudinal axis.
As described hereinbefore, motors 2 and 2' are pivotally mounted on frame 3. By inclining the grinding wheels 4 and 4' so that they converge towards table 7 the opposite faces of the work-piece 11 can be undercut so as to have a compound clearance angle.
Referring to FIG. 3, 4 and 5, there is shown part of a lathe tool 21. The tool 21 has a cutting tip 22 which is primarily intended for cutting grooves in work-pieces. In order to prevent the sides of the cutting tip 22 binding on the sides of the grooves the cutting tip is relieved, that is to say the cutting tip 22 tapers from the leading edge 20 both towards the body of the tool (FIG. 4) and towards the edge of the tool (FIG. 5). By inclining the grinding wheels 4 and 4' towards the table 7 and operating the hydraulic actuator in the manner described, a work-piece having the general outline of work-piece 11 can be ground to produce the lathe tool shown in FIG. 3 to 5. It should be noted that this lathe tool is not complete and further operations are necessary to appropriately finish and sharpen the leading edge 20.
Whereas rotary actuator 8 is shown with one pinion 16 and shaft 17 only, it will be appreciated that two or more pinions and shafts could be mounted between racks 12 and 13 with the longitudinal axes of the shafts aligned side-by-side. In such an arrangement each shaft could be connected to a respective holder so that several work-pieces could be ground sequentially.
The angle of the work-piece 11 can be set relative to the grinding wheels 4 and 4' by means other than a rotary actuator. In FIG. 6, work-piece 25 is held in a holder 26 which is mounted in a slot 27 in a drivable table 28. The slotted top plate of the table 28 is pivotally mounted about an axis Y--Y and, in the embodiment shown, can be moved up to 5° to either side of its central position relative to its direction of movement during grinding. A drive is connected to table 28 and is also connected to an actuator for rotating the table top plate about vertical axis Y--Y so that whilst the holder 26 is moving from left to right (as viewed in FIG. 6) the table 28 is angled about axis Y--Y so that for example, the " + 3°" mark is aligned with arrow 29. Conversely, after the holder 10 has moved past the grinding wheels and operated a trip, holder 10 moves from right to left and table 28 pivots about axis X--X so that the " -3°"mark is aligned with arrow It will be appreciated that the relative positions of the grinding wheels and the work-piece are similar as the work-piece passes the grinding wheels in both the arrangements shown in FIG. 1 and 6.
The hydraulic rotary actuator illustrated in FIG. 2 is the type MTV2 manufactured by Matthews Hydraulics, Horsenden Lane, South Greenford, Middlesex, England.