US1109277A - Grinding-machine. - Google Patents

Description

G. BLECHER.

GRINDING MACHINE.

APPLICATION FILED AUG. 2a, 1913.

Patented Sept. 1, 1914,

2 SHEETS-SHEET 1 C. BLECHER.

' GRINDING MACHINE.

APPLICATION FILED we. 2a, 1913.

1,109,277. V Patented Sept. 1, 1914.

, 2 SHEBTS8HEET 2.

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CARL BLECHER, OF BERLIN, GERMANY.

GRINDING-MACHINE.

To all whom it may concern Be it known that I, CARL BLECHER, citizen of the free town of Hamburg, residing at 110 Alexandrinenstrasse, Berlin, in the German Empire, have invented certain new and useful Improvements in Grinding- Machines, of which the following is a specifieation;

This invention relates to a machine for grinding cylindrical bodies by means of a flat grinding element and is particularly adapted for grinding copper printing cylinders. Hitherto in grinding machines of this type it has been proposed to allow the fiat grinding element to rotate while moving it longitudinally over the work. In order to obviate-scratches such as may be caused by particles becoming loosened at the center of the grinding element. the latter has also been moved transversely over the work; Unless the grinding element is moved transversely over the Work, there is also the danger of a projection or boss forming at the center-of the grinding elementif its pivotal axis does not always intersect the axis of the work.

According to the present invention, the grinding action'is attained by imparting-a circular motion to the grinding element about an eccentric axis while to obviate scratches and obtain uniform wear, the grinding element is slowly rotated about its geometric axis, this rotation being however immaterial to the grinding operation. The rotation of the grinding element about its geometric axi's may be very small and takes plac only to such an extent that all the points on the face of the grinding element are brought as far as possible uniformly into action on the line of contact with the work, in order to prevent irregular wear or the formation of grooves in the face of the grinding element. In this manner, a uniform grinding action is obtained, and since all the points on the face of the grinding element, come equally into action, in contradistinction to a grinding element rotated for grinding purnoses at a high speed solely about its geometric axis, the danger of particles breaking off in the center of the grinding element is obviated. The grinding element can be comparatively easily mounted and driven and may be supported on a shaft carried in fixed bearings so that itmay be pressed a ainst the work on axially moving the'shaft.

Specification of Letters Patent.

Application filed August 28, 1913.

Serial No. 787,121.

In order that the invention may be more,

Patented Sept. 1, 1914.

clearly understood, reference is made to the accompanying drawings, illustrating two embodiments of the invention by way of example.

Figure 1 is a side view, partly in s ti of such parts of the machine as are'necessary for the invention to be understood. Fig. 2 is a plan view of Fig. 1 and Fig. 3 a side view, partly in section, on the line m-x of Fig. 2. Figs. 4 and 5 are side and lan views respectively of a slightly modified form of Fig. 1. Referring to Figs. 1, 2 and 3 of the drawingsz The flat grinding element a, which rests upon the work to to be ground, is supported in a tool holder 7) which carries a disk-shaped head plate I) having a circular recess 111 which is rotatably fitted an eccentric 0 mounted on a rotatable driving shaft (1 carried in fixed bearings. On a collar b fixed on the tool holder 6 is secured a spur wheel 6 meshing with a toothed rack having an eye at its end f through which is fitted a vertical rod g so that the rod f may move up and down at its end f over the rod 9. A weight g secured to one end of a cord 2', which passes over a pulley n on the rod 9 and is secured at its other end to a hook Z on the end of the rack f, balances the weight of the rack f at this end. The toothed rack f passes through a guide shoe 72 which is loosely and rotatably mounted on the collar 6 of the tool holder (2. This permits of a relative movement between the rack f and holder 6 thus insuring the engagement of the teeth between the spur wheel 6 and rack If the driving shaft (Z is carried in fixed bearings as hereinbefore described, the work 111 must be slowly rotated and moved axially to and fro in order that the whole of its cylindrical surface may in succession be subjected to the grinding element a. If, for this purpose, the work is mounted on a slide similar to a lathe carriage, the vertical rod g must be secured to the same slide. The rod 9 will then slowly move the rack f to and fro through the shoe h during the axial feed of the work and thus impart a corresponding slow to and fro rotary motion to the spur wheel 6 and grinding element a about their common axis, this rotary motion being preferably about 180 or slightly more for each to and fro movement of the work w. By mounting the shaft d in a similar manner to the driving shafts of milling machines or the like, the grinding element a can be pressed down upon the work w with the necessary pressure by the downward movement of the shaft (1. Apart from the rotation of the spur Wheel 6 in one direction about its center during the feed of the work in one direction, the spur wheel e rolls to and fro on the rack f owing to the throw imparted by the eccentric to the spur wheel e in the direction of the axis of the work. Thus, during the feed of the work in one direction, the grinding element a during its circular motion about the axis of the shaft d, and in addition to its slow rotation in one direction about its center, due to the slow sliding movement of the rack f, also makes a rocking movement about its center, this rocking movement being alternately added to and subtracted from its slow rotation. This additional rocking motion of the grinding element about its center is, however, so slow that it is of no importance to the grinding action.

In the modification illustrated in Figs. 4 and 5, a spur wheel is is employed instead of the toothed rack f of Figs. 1 to 3. The spur wheel is is mounted on a rod m having a slotted guide m embracing the vertical rod 9 which in this case may be fixed. In order to rotate the spur wheel at a slow speed, the latter is driven by means of a flexible shaft 0 from any suitable source of power. In the case, when this eccentric c is rotated by the shaft d, the spur wheel e rolls on the spur wheel is, during its circular motion about the axis of the shaft d, in a similar manner to the rolling of the spur wheel e on the rack f in Fig. 1, and is also rocked to and fro about its center, this rocking motion being alternately added to and subtracted from the slow rotation imparted by the spur wheel k. Thus in this case the compound rotary motion of the grinding element (1, obtained by the rack f in Figs. 1 to 3, is also obtained during the circular grinding motion about the shaft d.

Assuming now that the spur wheels e and I: in Figs. 4 and 5 are removed, and that the grinding element a does not rest on the work 10; then it will be clear that the grinding element a will describe a circular movement about the shaft d together with the cocentric 0 without its pivot pin m rotating in the hollow bearing 6 of the rod 111.. It would thus act as if its pivot pin m were in one piece with the bearing 6 As soon as the grinding element a bears on the work, however, the friction, during the grinding operation, arrests the grinding element a and pin m and tends to set the grinding element a into an irregular rotary motion and 'to rotate the pin m in the bearing b the speed of the rotation being greatest in the two positions of the circular motion of the grinding element where the frictional forces on the grinding element act on one side of its center, that is, in the extreme positions laterally of the axis of the work. In the other extreme positions, where the grinding element lies symmetrically over the axis of the work, this rotar motion will be practically nothing, since the frictional forces on both sides of the center of'the grinding element act in opposite directions, thus equalizing each other. The direction of the rotation of the grinding element about its center will be the same as the circular motion owing to the frictional moments. In order that the extent of this irregular rotation about the center of the grinding element, due to the frictional turning moments and which does not permit of the desired relative movement between the grinding element and the work essential to grindin may not be too great, so that the aforesaid relative movement will take place, means are provided for retarding this irregular mo-, tion, this means, as shown in Fig. 4 comprising a pinching screw m acting on the pivot pin m By correspondingly tightening the screw m, the rotation of the pin m and grinding element a relatively to the rotation of the eccentric 0 can thus be so regulated that it is limited without being entirely prevented, thus insuring uniform wear of the face of the grinding element. In this manner, a slight rotation of the grinding element and variation in its position can be attained without the use of special mechanism such as the rack f or spur wheel is. The compound rotary motion may, however, be imparted to the grinding element in any other suitable manner.

I claim 1. In a machine for grinding cylindrical bodies, a fiat grinding element, means for imparting a circular motion thereto about an axis eccentric to said element, means for imparting a slow rotary motion to said element about its geometric axis, and means for imparting an oscillatory motion to said element about its geometric axis, said oscillatory motion being alternately added to and subtracted from said rotary motion.

2. In a machine for grinding cylindrical bodies movable to and fro axially, a flat grinding element, means for imparting a circular motion to said element about a fixed axis eccentric thereto, and means for imparting a small reciprocatory angular motion to said element about its geometric axis during the axial movement of the work, the change period of the angular motion corresponding to the change period of the to and fro movement of the work.

3. In a machine for grinding cylindricalbodies, a stationary rotary shaft, an eccentric thereon, a flat grinding element driven by said eccentric, means for simultaneously imparting a slow rotary motion to said element about its geometric axis, and means for simultaneously imparting an oscillatory motion to said element about its geometric axis.

4. In a machinefor grinding cylindrical bodies, a stationary rotary shaft, a flat grinding element rotatable about its geometric axis, an eccentric on said shaft imparting a circular motion to said element about said shaft, a gear wheel rotatable with said element, a member with which said gear wheel makes rolling engagement and means for imparting a slow movement to said member for transmitting a slow rotary motion to said wheel andelement.

5.'In a machine for grinding cylindrical bodies movable to and fro axially, a sta tionary rotary shaft, a flat grinding element rotatable about its geometric axis, an eccentric on said shaft imparting a circular motion to said element about said shaft, a gear wheel rotatable with said element, and a movable transmission member engaging with said gear wheel for'imparting a slow rotary motion to said wheel and element.

(3. In a machine for grinding cylindrical bodies, movable to and fro axially, a. stationary rotary shaft, an eccentric rotatable therewith, a flat grinding element, rotatable on said eccentric, a rotary transmission member rotatable With said element and a transmission member making rolling engagement with said rotary member.

7. In a machine for grinding cylindrical bodies, a stationary rotary shaft, an eccentric disk rotatable therewith, a flat grinding element, a holder for said element having a circular recess in which said disk is rotatably fitted, a gear wheel rotatable with said element, a member with which said wheel i makes rolling engagement and means for imparting a slow movement to said member for transmitting a slow rotary motion to said wheel and element.

8, In a machine for grinding cylindrical bodies, a stationary rotary shaft, a flat grinding element rotatable about its geometric axis, an eccentric on said shaft imparting a circular motion to-saidelement about said shaft, a gear Wheel rotatable with said element, a slowly rotated gear wheel meshing with the aforesaid gear wheel, and means for enabling said second-mentioned gear wheel to move in circular motion with said element.

9. In a machine for grinding cylindrical bodies, a stationary rotary shaft, an eccentric thereon, a strap surrounding said eccentric, a hollow bearing carried by said strap, a flat grinding element, a pivot pin on said element fitting in said bearing, and a pinching screw pasing through said bearing and engaging said pin for retarding the rotation of said element about its geometric axis.

In testimony whereof I have afiixed my signature in presence of two witnesses.

CARL BLE CHER.

Witnesses:

VVOLDEMAR HAUr'r, HAn'rwrc P. NEUBANCE.

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