US2112215A - Bed motion - Google Patents

Description

4 Sheets-Sheet l J. R. WOOD BED MOTION Aw. -1, /1,I

March 22, 1938.

original Filed Nov. 26', 1954 March 22, 1938.

J. R. woon l l BED MOTION 4 Sheets-Sheet 2 March 22, 193s. J. R. woon .2,112,215

BE MOTION Original Filed Nov. 26, 1934 4 Sheets-Sheet 3 March 22, 1938. J. R'WOQD 2,112,215

BED MOTION original Filed Nov. 2e, 1934 4 shee1s-sheet 4 VPatented Mar. 22, 1938 UNITED STATES PATENT OFFiCE BED MOTION Application November 26, 1934, Serial No. 754,837

Renewed May 14, 1937 f 12 Claims.

This invention relates to improvements in bed motions, that is to say mechanism for reciprocating the bed of a printing press or other machine at a constant speed during the intermediate por- 5 tion of its travel, and for producing a gradual slowing down and stopping and a gradual acceleration in the opposite direction during the end portions of the bed travel.

One of the objects of the invention is the provision of relatively simple mechanism for accomplishing the smooth reciprocation of a heavy bed, so as to make high speeds possible without undue strain upon the machine or its mounting.

A further object is the provision of driving mechanism such that gearing with teeth of fine pitch is utilized during the intermediate or printing travel of the bed, While gearing with teeth of coarse pitch is utilized for theV end portions, thereby insuring accuracy for the motion of the bed during the interval in which the printing is performed, and providing heavy strong connections during the end motion intervals when accuracy is not important.

Other objects andfeatures of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which Fig. 1 is a side elevational View partially in vertical section, illustrating an application of the invention to a printing press.

Fig. 2 is a plan view, partially in horizontal section on the line 2--2 of Fig. 1, and with a portion of the bed broken away to more clearly disclose the driving mechanism.

Figs. 3 and 4 are transverse vertical sectional views taken substantially on the lines 3 3 and 4-4 of Fig. 1. v

Figs. 5, 6 and '7 are diagrammatic views illustrating the positions of the driving mechanism at different points of the bed travel, and

Fig. 8 is a diagram representing the time intervals elapsing during the different portions of the travel of the bed.

Similar reference characters refer to like parts throughout the views.

In the drawings, I have illustrated the frame of a reciprocating bed printing press as comprising side members I!! and cross members or struts I I, I2 and I3. Supported upon the cross members I I, I2 and I3 are four longitudinally extending rails I4, i5, i6 and I'I, the upper surfaces of which constitute ways. Running upon these Ways there are a series of rollers i8 which support the bed I9 of the machine. The rollers I3 are maintained in position by a frame or cage in the usual manner, this part of the machine being omitted from the disclosure for the sake of clearness.

The bed, as previously indicated, has two classes of movement, a movement at constant speed during the intermediate part of the travel in both directions, as represented by the lines A-Bl and D--E of Fig. 8, and a harmonic movement of deceleration and acceleration at each end of the travel represented by the semi-circular lines B-C-D and E-F-A of Fig. 8. Twothirds of the time of each cycle is occupied in the movements A--B and D-E, and one-third of the time is occupied in the two end movements B--C-D and E-F-A, that is to say each complete end movement occupies one-half of the length of time of an intermediate movement. The distances traveled by the bed during its different movements are indicated by the dimension lines in Fig. 8.

The constant speed movements of the bed are produced by the use of an inverted rack 2U and a pinion 2l meshing therewith, each having teeth of relatively ne pitch. The rack is secured to the under surface of the bed by screws 22 or the like. The pinion 2i is keyed to a shaft 23 which has bearing in the side frame members I0, and on its forward end outside the frame of the machine it carries two pinions 24 and 25 which are likewise provided with teeth of relatively ne mesh.

On a shaft 26, which is rotatably mounted in the forward frame member I0, there is keyed a rotatable member or wheel 21 of large size, upon which is mounted near the rim an internal gear sector 28. An external gear sector 28, offset axially from the sector 2B and positioned radially inward therefrom, is also mounted upon the rotatable member. These two sectors are positioned diametrically opposite each other. Their teeth are of relatively ne pitch to mesh with the teeth of the pinions 24 and 25, and each sector has one tooth more than the number which could be included within 120 of arc. The sector 28 is adapted to mesh With the outer side of pinion 2t for producing rotation of shaft 23 in an anticlockwise direction, while the sector 29 is adapted to mesh with the inner side of the pinion 25 for producing rotation of shaft 23 in a clockwise direction. The gearing is so designed that the same number of revolutions of shaft 23 Will be produced by each of the sectors. Between the end of one sector and the adjacent end of the other sector there is an angle of approximately 60, during which neither sector is in driving relation with the shaft 23. During the intervals corresponding to these 60D angles the reversing motion of the bed takes place, and at such times the rack 2E) drives the shaft 23 through pinion 2|, instead of being driven by the pinion.

On the periphery of the rotatable member 2T there is an external gear 3@ with teeth of relatively fine pitch which meshes with a gear 3 la keyed to the shaft 32. Fixed on the same hub with gear 3m is a gear Bib which is provided with teeth of a relatively coarse pitch. The latter gear meshes With a pinion 33, also having teeth of coarse pitch, that is keyed to a shaft 34 upon which is mounted a pulley 35. Power for operating the machine may be applied to pulley 35 by means of a belt, for example. Driving force for the shaft 32, upon which the heavy loads incident to the reversal of motion of the bed are imposed, is therefore applied directly to that shaft through heavy gearing rather than through the fine gearing used to drive rack 20.

The gear 3|] on the periphery of the rotatable member 2l may also mesh directly with gears 3E and 31 mounted upon or associated with impression rolls 38 and 39 respectively, thereby providing a close and accurate connection between the bed and impression roll movements. That feature of the invention however, together with various other features having to do especially with printing presses, is covered in a separate application led of even date herewith.

The mechanism for accomplishing the harmonic reversing movements will now be described. A pair of reversing racks 40a and 4Gb are attached to the under side of the bed i9 just behind the rack 2|). These racks are mounted in alignment and their centers are spaced apart a distance somewhat less than the length of rack 20. Their teeth are of a relatively coarse pitch. A gear 4 I, mounted upon a short shaft 42 which has bearing in the rails l5 and I6, is adapted to mesh with the racks 43a and 4Gb during the end portions of the bed travel.

The gear 4| is arranged to be rotated in opposite directions alternately by a driving rack 43 which meshes with the under side of the gear and is attached by means of screws 44 or the like to a yoke 45 that is slidably mounted upon a guide bar 46 secured by suitable means to the rail iii or other fixed portion of the machine. The yoke 45 carries a vertical channel guide 47 in which runs a roller 48 that is mounted upon a pin carried by a crank disc 49 which is keyed to shaft 32. The effective crank length is the same as the pitch radius of gear 3 ia. The parts 45, 4l, 48 and 49 therefore constitute a scotch yoke mechanism for producing simple harmonic motion of the rack 43, which motion is transmitted at the proper times through gear 4! to the reversing racks 40a and 4Gb. The rack 43 is of course reciprocated at all times, but it does work only during one-third of each cycle of the bed, that is during the periods represented by the lines B-C-D and E-F-A of Fig. 8.

The gears 3m and 3i] have pitch diameters in the ratio of l to 3. The sectors 28 and 29 each occupy an angle of 126. Hence the constant speed travel of the bed in either direction corresponds to a complete revolution of the crank pin, and if the time occupied by a complete revolution of the crank pin is taken as 1, then the time occupied by a complete reciprocation of the bed is 3. This ratio of 1 to 3 is the preferred ratio, but other ratios, as 1 to 5 or 1 to '7, may also be 111- ployed. In any event, each end movement of the bed occupies one-half of a crank revolution, While the constant speed movement in each direction may occupy one, two, or more complete revolutions of the crank. The constant speed movement must occupy one or more complete revolutions of the crank, as distinguished from half revolutions as otherwise the crank movement would come in the wrong direction at one end of the travel. Hence the ratio of end motion to constant speed motion must be l to some odd number greater than 1, which means that the pitch diameter ratios of gears 3Ia and 30 must also be 1 to some odd number greater than 1.

The axis of gear 4| is located preferably in the same vertical plane with the axis of shaft 26, that is to say half Way between the impression rolls 38 and 39, because that is the desired center line of travel of the bed. In the case of my construction it is readily possible to utilize this most advantageous position on account of the fact that the shaft 23 is preferably offset from the plane through the axis of shaft 26.

Operation-In Fig. 1 the bed is shown in its dead center position at the right hand end of its travel, in other Words in the position represented by the point C in Fig. 8. At this time the crank pin roller 48 and the yoke 45 are on left dead center, and the inertia of the yoke and associated parts in moving to that position has counteracted to some extent the inertia of the bed in moving to the right. As the crank pin roller 48 rotates clockwise from the position of Fig. 1 to that of Fig. 5, the yoke 45 and its rack 43 move toward the right with a regular acceleration, and thereby rotate gear 4| in an anti-clockwise direction with the same acceleration. The bed then travels toward the left with a gradual acceleration until, at the point illustrated in Fig. 5, it has attained maximum speed. This corresponds with point D in Fig. 8. During this acceleration of the bed from zero to maximum speed, the shaft 23 is similarly accelerated in an anti-clockwise direction by its engagement with the bed through the rack 2Q and pinion 2|. When the bed travel reaches its maximum at the point D the rack 40a leaves the gear 4| and the gear sector 28 engages pinion 24, continuing its rotation in the anti-clockwise direction. Motion is then transmitted through the shaft 23 and the pinion 2| in an anti-clockwise direction, to move rack 20 and bed I9 toward the left at a constant speed. Such constant speed is maintained until the bed arrives at the position illustrated in Fig. 6, which corresponds with the point E in Fig. 8. At this point the gear sector 28 leaves pinion 24 and gear 4| begins to mesh with rack 4Gb. Yoke 45 is now in a maximum speed position, but as the roller 48 continues from the position illustrated in Fig. 6 through the next of its rotation, the yoke decelerates while moving toward the right. In so doing the gear 4| is rotated anti-clockwise and the bed I9 is accordingly caused to travel a further short distance toward the left, that is to the position indicated by the point F in Fig. 8. At that point the direction of movement of the yoke 45 is reversed and the bed begins its travel toward the right from F to A in Fig. 8. During this reversal movement corresponding to the line E-F-A, the rotation of shaft 23 is of course decelerated to zero and then accelerated in the opposite or clockwise direction to maximum speed, being driven by the bed in this portion of the cycle. In Fig. '7 the bed is in a position corresponding with the point A in Fig. 8, the rack 4Gb is just leaving the gear 4l, and the external gear segment 29 is just beginning to mesh with pinion 24. Rotation is thereby imparted to that pinion and to its shaft 23, continuing the rotation of the latter in a clockwise direction, producing travel of the bed to the right at constant speed, which continues until the bed reaches the position corresponding to point B in Fig. 8. The reversing mechanism then comes into play, stopping the bed at the point C and ending the cycle.

While I prefer to employ simple harmonic motion for reciprocating the rack 43 in order to impart to the bed at the ends of its travel a deceleration and an acceleration as smooth and even as possible, it will be understood that a less costly mechanism for the reciprocation of the rack, as for instance a simple crank mechanism, could be employed without departing from the spirit of the invention in some of its broader aspects.

Other variations from the described structure may be employed. Accordingly I desire it to be understood that the scope of the invention is to be regarded as defined exclusively by the appended claims rather than by the foregoing description or the accompanying illustrations.

Having thus described my invention, I claim:

1. In mechanism of the class described, a re-V toothed portion, a segmental internally toothed portion and a segmental externally toothed portion, each of the said segmental toothed portions being adapted to mesh at different times with one of said pinions for actuating said gearing, mechanism for reversing the direction of motion of said bed at the ends of its stroke, a pinion meshing with said annular toothed portion of said rotatable element, and a crank pin carried by said pinion and operatively connected to said reversing mechanism for actuating the latter.

2. In a printing press, a reciprocating bed, gearing for driving said bed in alternately opposite directions, including two concentric pinions, a rst gear vertically disposed and adapted to rotate once for each cycle of said bed, a segmental internally toothed member and a segmental externally toothed member, each of said members being connected with said first gear to rotate therewith and disposedon the same side of said bed as said iirst gear, each of said segmental members meshing intermittently with a corresponding one of said two concentric pinions for driving said bed in alternately opposite directions throughout the major portion of the stroke thereof, mechanism for reversing the direction of motion of said bed at the ends of the stroke thereof including a pair of racks carried by said bed, a second gear adapted to mesh with one rack of said pair at each end of the stroke of the bed,

a rack continuously in mesh with said second gear, reciprocating means for imparting to said last-mentioned rack three reciprocations for each cycle of said bed, and means for driving said reciprocating means in timed relation lwith said first gear.

3. In a printing press, a reciprocating bed, gearing for driving said bed in alternately opposite directions including a rack carried by said bed, a first gear in continuous mesh with `said rack, a shaft fixed for rotation with said gear, two pinions fixed for rotation with said shaft,

a second gear vertically disposed and rotating once for each cycle of said bed, a segmental internally toothed member and a segmental externally toothed member each arranged to rotate with said second gear and disposed on the same side of said bed as said second gear, each of said segmental members meshing intermittently with a corresponding one of said two pinions for driving said bed in alternately opposite directions throughout the major portion of the stroke thereof, mechanism for reversing the direction of motion of said bed at the ends of its stroke, including a pair of racks carried by said bed, a third gear adapted to mesh with one rack of said pair at each end of the stroke of said bed, a reversing rack continuously in mesh with said third gear, a scotch yoke operatively connected to said reversing rackV for imparting reciprocating motion to the latter, a crank pin and crankshaft for reciprocating said scotch yoke, and a fourth gear meshing with said second gear and carried by said crankshaft, said fourth gear and second gear having a ratio of one to three, whereby said crankshaft and said second gear are maintained in timed relation to drive said scotch yoke three times for each cycle of said bed.

4. In mechanism of the class described, a reciprocating bed, a b-ed rack mounted thereon, a pinion meshing with said bed rack, a shaft for said pinion, means for driving said shaft in opposite directions comprising a rotating member having an outer internal gear sector and an inner external gear sector, two pinions mounted on said shaft, each of said last named pinions being adapted to mesh with one of said gear sectors, a pair of reversing racks mounted on said bed, a gear adapted to mesh with said last named racks during the end portions of the travel of the bed, a driving rack in constant mesh with said gear, and means for reciprocating said driving rack during each complete reciprocation of the bed an odd number of times greater than one.

5. In mechanism of the class described, a reciprocating bed, rack and pinion means for producing intermediate travel of the bed in both directions, said rack and pinion means comprising relatively fine teeth, means for drivingsaid rack and pinion means for producing reciprocation of the bed in opposite directions through the intermediate portion of its travel, a pair of coarse toothed reversing racksY mounted on the bed, a gear wheel element with coarse teeth adapted to mesh with said reversing racks during the end portions of the bed travel, a coarse toothed rack element meshing with said coarse toothed gear wheel element, and means for reciprocating one of said elements, whereby the strain of reversing the direction of bed travel is taken upon coarse gear teeth and whereby the constant speed travel of the bed is eected by relatively iine gear teeth.

6. In mechanism of the class described, a reciprocating bed, a bed rack with fine pitch teeth, a pinion meshing with said bed rack, a shaft upon which said pinion is fixed, a pair of spaced reversing racks mounted in alignment lcngitudinally of said bed, said reversing racks having teeth of coarse pitch, a gear adapted to mesh with said reversing racks during the end portions of the travel cf the bed, means for turning said gear in opposite directions with simple harmonic motion, said means comprising a crank shaft, and a train of gears operatively connecting said crank shaft with said rst named shaft for imparting rotation to said first named shaft in opposite directions at spaced intervals, said train of gears having teeth of ne pitch, and means for applying power to said crank shaft.

'7. In mechanism of the class described, a reciprocating bed, a bed rack with teeth of fine pitch, a pinion meshing with said bed rack, a shaft upon which said pinion is xed, a vertical rotating member having an outer internal sector and an inner external gear sector offset axially, the teeth of said sectors being of ne pitch, two pinions mounted upon said shaft, each pinion being adapted to mesh with one of said gear sectors, a pair of spaced reversing racks mounted in alignment longitudinally of said bed, said reversing racks having teeth of coarse pitch, a gear adapted to mesh with said reversing racks during the end portions of the travel of the bed, a driving rack meshing with said gear, means for reciprocating said driving rack comprising a crank shaft, an external gear with iine pitch teeth on said rotating member, a gear on said crank shaft meshing with said extern-a1 gear for operatively connecting the crank shaft with the rst named shaft for imparting rotation to said rst named shaft in opposite directions at spaced intervals, and means for applying power to said crank shaft.

8. In mechanism of the class described, a reciprocating bed, a bed rack, a pinion meshing with said bed rack, a shaft upon which said pinion is xed, a rotating member having an outer internal gear sector and an inner external gear sector, two pinions mounted on said shaft, each of which meshes with one of said gear sectors, the center of said rotating member being spaced l-aterally from said shaft, a pair of spaced reversing racks mounted in alignment on said bed, a gear arranged with its axis in the same vertical plane with the axis of said rotating member adapted to mesh with said reversing racks during the end portions of the travel of the bed, a driving rack meshing with said last named gear, and means geared to said rotating member for reciprocating said driving rack.

9. In a printing press, a reciprocating bed, gearing for driving said bed in alternately opposite directions including two concentric pinions, a iirst gear vertically disposed and adapted to rotate once for each cycle of said bed, a segmental internally toothed member and a segmental externally toothed member, each of said segmental members being connected with said first gear to rotate therewith and disposed on the same side oi said bed as said iirst gear, each of said segmental members meshing intermittently with a corresponding one of said two concentric pinions for driving said bed in alternately opposite directions throughout the major portion of the stroke thereof, mechanism for reversing the direction of movement of said bed at the ends of its stroke, -a crank pin for actuating said mechanism, and a second gear rotating with said crank pin and meshing with said iirst gear.

l0. In a printing press, a reciprocating bed, gearing for driving said bed in alternately opposite directions, including two concentric pinions, a first gear vertically disposed and adapted to rotate once for each cycle of said bed, a segmental internally toothed member and a segmental externally toothed member, each of said members being connected with said rst gear to rotate therewith and disposed on the same side of said bed as said first gear, each of said segmental members meshing intermittently with a corresponding one of said two concentric pinions for driving said bed in -alternately opposite directions throughout the major portion of the stroke thereof, mechanism for reversing the direction of motion of said bed at the ends of the stroke thereof including a reciprocable rack, means for reciprocating said rack three times for each cycle of said bed, means for intermittently placing said rack into operative relation with said bed for reversing the latter, and means for driving said reciprocating means in timed relation with said rst gear.

11. In mechanism of the class described, a reciprocating bed, a bed r-ack mounted thereon, a pinion meshing with said bed rack, a shaft for said pinion, means for driving said shaft in opposite directions comprising a rotating member having an outer internal gear sector and an` inner external gear sector, two pinions mounted on said shaft, each of said last named pinions being adapted to mesh with one of said gear sectors, a driving rack, means for placing said driving rack into operative relation with said bed during the end portions of the travel of the bed only for erecting reversal thereof, and means for reciprocating said driving rack during each complete cycle of the bed an odd number of times greater than one.

l2. in a printing press, a reciprocating bed, gearing for driving said bed in alternately opposite directions including a rack carried by said bed, a first gear in continuous mesh with said rack, a shaft fixed for rotation with said gear, two pinions fixed for rotation with said shaft, a second gear vertically disposed and rotating once for each cycle of said bed, a segmental internally toothed member and a segmental externally toothed member each arranged to rotate with sai-d second gear and disposed on the same side of said bed as said second gear, each of said segmental members meshing intermittently with a corresponding one of said two pinions for driving said bed in alternately opposite directions throughout the major portion of the stroke thereof, mechanism for reversing the direction of motion of said bed at the ends of its stroke, including a reversing rack, means for placing said reversing rack in operative relation with said bed during the end portions only of the travel of the bed, a scotch yoke operatively connected to said reversing rack for imparting reciprocating motion to the latter, a crank pin and crankshaft for reciprocating said scotch yoke, said crankshaft being driven to turn at three times the speed of said second gear, whereby said crankshaft and said second gear are maintained in timed relation to drive said scotch yoke three times for each cycle of said bed.

JAMES R. WOOD.

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