US2130021A - Grinding machine - Google Patents

Description

Sept 13, 19.38.

F. N EUGART GRINDING MACHINE Filed April 11, 1938 2 Sheets-Sheet 1 Sept. 13, 1938. F. NEUGART GRINDING MACHINE Filed April 11, 1938 2 sheet -s eet 2 Jarenfar: iA eu vri Patented Sept. 13, 1938 Edi Franz Neugart, Berlin-Charlottcnbnrg, Germany 2 Claims.

My invention relates to grinding machines, and more particularly to grinding machines of that type in which a grinding wheel is mounted to rotate on a swinging bracket, and a truing tool for the grinding wheel is arranged with its point on the are described by the perimeter of the grinding wheel when the bracket swings from the finish-grinding position of the wheel into its truing position.

It is an object of my invention to design a machine of this type as a circular grinding machine.

To this end, in combination with the parts aforesaid, I provide means for imparting relative reciprocation to the grinding wheel and the work in the direction of their axes, for instance, means for reciprocating the slide in which the work is held, and means controlled by the reciprocation,

for instance, a cam and a pawl-and-ratchet mechanism, for swinging the bracket stepwise at the end of one of the strokes making up the reciproca- I tion.

The swinging movement imparted to the grinding wheel through the bracket must be such that the grinding wheel moves at least as far as the minimum distance from the truing tool and from the work.

By designing a grinding machine in conformity with my invention, the work, for instance, a cylinder, is ground true and exactly to size merely by swinging the grinding wheel.

In the accompanying drawings a machine embodying my invention is illustrated somewhat diagrammatically by way of example. I

In the drawings:

Fig. 1 is an elevation of the machine showing the position of its parts after the insertion of a fresh workpiece,

Fig. 2 is a plan view of the machine, and

Figs. 3, 4, and 5 are elevations like Fig. 1, showing, respectively, the roughing, truing, and finishing position of the machine.

Referring now to the drawings, the machine is equipped with a base plate I having at one side a bearing for a shaft 9, and at the other side a rib presenting an inverted V guide for the'work slide 2. Reciprocation may be impartedto the slide by any suitable means. In the present instance, a shaft 28 is mounted to rotate below'the inverted V guide and equipped with a threaded portion 29 engaging in a female thread in a downward extension of the slide. By reversing the spindle 29, for which any suitable automatic mechanism known in the art and not illustrated, may be provided, the work slide 2 is reciprocated as indicated by the arrow 3 in Fig. 2. A groove is made in the rib in parallel relation to the inverted V guide, and another downward extension of the slide 2, with a wedge 23 at its lower end, projects into the groove.

Mounted on the work slide 2 is a motor 5, Fig. 2, which, through suitable means such as a worm gear and a driver, rotates the work 5 shown as a cylinder between a pair of centers.

A lug 6 projects upwardly from the work slide 2 and a truing tool having a knurled handle I anda point 8, is adjustably secured in the ex-.

tension.

A bracket it is mounted to swing about the shaft 9 on the base plate I and is supported by a cam H. The cam is keyed on a shaft mounted in a bearing on the base plate 5. A grindingwheel carriage i3 is mounted to slide on the bracket l0 and is adjusted by a spindle l2 connected to its lower end and provided with a hand wheel. Mounted at the upper end of the carriage is the shaft 25 of a grinding wheel i i. The grinding-wheel shaft 25-is driven from a motor I9 on the carriage it by pulleys l5 and It, and a belt It. By these means, the grinding wheel M is rotated in the direction of the arrow ii.

The cam i i which supports the swinging bracket ii), is turned stepwise by a pawl-and-ratchet mechanism. A double-armed lever 22 is fulcrumed on the base plate I and is so arranged that its right-hand end is engaged and depressed by the wedge 23 of the work slide 2 when the slide has completed one of its strokes. A pawl 2i is pivoted to the left-hand arm of the doublearmed lever 22 and is drawn into the teeth of a ratchet wheel on the shaft of the cam II by a spring. By these means, the cam H is turned in the direction of the arrow '26 for the angle corresponding to one pitch of the ratchet wheel 22, as often as the wedge 23 strikes the doublearmed lever 22.

The operation of the machine will now be described, it being assumed that a cylinder 5 having the initial diameter shown in Fig. 1, is reduced to the final diameter shown in Fig. 5. The proportion of the two diameters has been much exaggerated in the drawings.

The grinding-wheel carriage I3 is adjusted by means of the spindle l2, and the truing tool is adjusted by its handle .1, until the perimeter of the grinding wheel M, and the point 8 of the tool, are on the are 24 of a circle about the axis of the swinging shaft 9. The are 24 is tangent to the finish-ground work piece 5, Fig. 5.

At the beginning of the operation, Fig. 1, the

cam H holds the bracket it in such a position that the grinding disk M is off the work. 5, and so a freshpiece s is readily inserted in this position.

The motors t and is are now started, and the work 5 and the grinding wheel it are rotated by the means described. The cam ii is turned through one pitch of the ratchet teeth as often as the work slide 2, during its reciprocation, arrives at the end of one of its strokes. Upon the stepwise turning of the cam ii in the direction of the arrow 26, the bracket it and the grinding wheel I4 are gradually lowered in the direction of the arrow 2'! in Fig. 1 until the grinding wheel bears against the work 5 from above, Fig. 3. The work is now ground while the work slide 2 is reciprocated, and the cam it turned stepwise in the direction of arrow 26. As often as the work slide 2 arrives at the end of one of its strokes during its reciprocation in the direction of the arrow 3, the cam l i is turned, as described, allowing the bracket it and the grinding wheel it to descend. The work 5 is now roughed until it has nearly the final diameter, Fig. 5. Since the cam l l is fed at one end of a stroke performed by the work slide 2, the wheel is moved nearer the work when it is at one end of the work, or it may even be moved beyond this end of the work.

When the work 5 has been roughed, the cam l! gradually moves the grinding wheel 5 3 away from the work in upward direction, against the arrow topmost position, Fig. 4, the carriage it is advanced, by the spindle l2, for a distance at least equal to the wear it has undergone during the roughing of the work 5. In the topmost position, the grinding wheel M is nearest the truing tool, the axes of the shafts 9, 25, and the point 8 of the tool being positioned in a straight line. The grinding wheel M is now trued by the point a moving across it as the slide 2 reclprocates.

The trued grinding wheel is lowered by the cam ll along the'arc 24 which, as described, is tangent to the work 5 and extends through the point 8 of the tool. The work 5 is now finished, and the finishing cut is completed when the axes of the shafts 9, 25, and the axm about which the work 5 is rotated, are in a straight line, as shown in Fig. 5. Preferably, the downward movement of the grinding disk ii is mntinued beyond the straight-line position in order to make sure that the work 5 has been finished to the required diameter throughout, and that this diameter is nowhere exceeded.

After the work 5 has been finished, the grinding wheel i4 is returned into the position Fig. 1, the finished work is removed and a fresh work piece is.inserted.

The work is finished exactly true and exactly to size all over its length by simply swinging the Before the grinding wheel it arrives in its grinding wheel H by means of the stepwise turning cam l l, as described.

The circular grinding machine according to my invention, besides the simplicity of its operation, as stated, possesses various other advantages over the known circular grinding machines. One of these is that it is not necessary to retract the carriage with the grinding wheel after a workpiece has been finished, to prevent damage to the grinding wheel by placing it against the work at the full thickness of the grinding allowance.

Another advantage of my machine is that the angle through which the grinding wheel is swung, may be varied without deteriorating the accuracy of the work, as against known circular grinding machines in which the grinding-wheel carriage must only be advanced so far that not more than the grinding allowance is removed.

Still another advantage of my machine is that its operation is automatically subdivided into a roughing and a finishing period, without varying the movement of the grinding wheel toward the work.

It is understood that the range of usefulness of my machine is not limited to the grinding of a solid cylinder, as described, but that my inventlon also includes other machines such as inside grinders, or grinders without centers.

I claim:

' 1. In a circular grinding machine, a base plate, a bracket mounted to swing on the base plate, a grinding wheel mounted to rotate on the bracket, a truing tool arranged with its point on the arc of a circle described by the perimeter of the grinding wheel, and tangent to the finish diameter of the work, a work slide on the base plate, means for imparting relative reciprocation to the grinding wheel and the work on the slide, in the direction of their axes, and means controlled by the reciprocation ior swinging the bracket stepwise at least as far as the positions where the grinding wheel is nearest to the truing tool, and to the work, and for performing such stepwise swinging at the end of one of the strokes making up the reciprocation.

2. In a circular grinding machine, a base plate, a bracket mounted to swing on the base plate, a grinding wheel mounted to rotate on the bracket, a truing tool arranged with its point on the arc of a circle described by the perimeter of the grinding wheel, and tangent to the finish diameter of the work, a work slide on the base plate, means for reciprocating the work slide, and means controlled by the work slide for swinging the bracket stepwise at least as far as the positions where the grinding wheel is nearest to the truing tool, and to the work, and for performing such stepwise swinging at the end of one of the strokes making up the reciprocation.

FRANZ NEUGAR'I.

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