GB2228984A - Rotary drive adjustment - Google Patents

Abstract

A rotary drive has a drive shaft (10) carried by a support (11) movable in a guide frame (12) by means of shafts (21) coupled by sprockets (26) and a chain (27) for simultaneous rotation by a wrench (28), the shafts having screwthreaded portions (21B) engaging nuts (19) on the support (11) with twice the pitch of portions (21A) engaging nuts (20) on a carrier (18) for idlers (17), and a driven member (13) on the drive shaft (10) engages a double-sided gear-belt (16) also engaging a driving member (14) on a fixed axis (15) and guided by the ilders (17), whereby vertical adjustment of the position of the driven member (13) is not accompanied by any phase shift. <IMAGE>

Description

ROTARY DRIVE ADJUSTMENT This invention relates to a rotary drive with perpendicular axis adjustment, such as the drive for a rotary carton transfer mechanism in packaging machinery timed to be in phase with an associated mechanism, such as a product inserter, the axis being adjustable towards or away from a conveyor, especially to suit different nominal heights of cartons.

It is known to provide a rotary drive with a drive shaft carried by a support member movable along a fixed guide by screw means, a rotary driven member (e.g., a sprocket) secured to the drive shaft, a rotary driving member on a fixed axis (e.g., a sprocket driven by a motor, usually through a gearbox), an endless positive transmission member (e.g., a chain or gear-belt) engaging the driven and driving members, and an idler (or jockey) for taking up slack in the endless transmission member allowing for adjustment (with the drive stationary) of the axis of the drive shaft perpendicular to its axis.

However, such adjustment results in a slight phase shift of the rotary driven member such as could carry the rotary drive out of phase with an associated mechanism unless the rotary driven member is rotationally adjustable with respect to the drive shaft, the effecting of which rotational adjustment is time consuming, especially since it is essential to ensure that there can be no slip between the rotary driven member and the drive shaft during or after adjustment.

The object of the invention is to provide a rotary drive with perpendicular axis adjustment that does not result in any phase shift of the rotary drive.

According to the present invention a rotary drive comprises a drive shaft carried by a support member movable along a fixed guide, a rotary driven member secured for rotation with the drive shaft, a rotary driving member on a fixed axis, an endless transmission member positively engaging both the driving and driven members, a pair of idlers also engaging the transmission member, with the driving member engaging the transmission member between the idlers, with the driving member disposed nearer the driven member than are the idlers, and with four straight runs of the transmission member between the idlers and the driving member and the driven member all generally parallel to the direction of movement of the support member along the guide, a carrier for the idlers, nut means on the support member, and nut means on the carrier, and screw means extending between fixed bearings and engaging with both nut means, screwthreads in the nut means on the support member having the same hand but twice the pitch of screw threads in the nut means on the carrier, whereby, upon rotation of the screw means to move the support member and with it also the drive shaft and driven member perpendicular to their common axis, the carrier and with it also the idlers move in the same direction but by half the amount, these movements being accompanied merely by slight rotation of only the idlers in opposite directions as the straight runs of the transmission member change length, there being no phase shift of the driven member and drive shaft in consequence.

The driving and driven members may be transposed without affecting the effectiveness of the invention.

The fixed guide is preferably a frame having a pair of parallel side members slidably engaged by shoes on the support member, and having cross-members carrying fixed bearings for a pair of shafts constituting the screw means, and disposed one parallel to and adjacent each side member, the nut means being constituted by a pair of nuts on the support member and a pair of nuts on the carrier, each shaft having two screwthreaded portions one of which engages the respective nut on the carrier while the other has a screwthread of the same hand but twice the pitch engaging the respective nut on the support member, and the shafts being coupled to each other (as by sprockets and a chain) for simultaneous and equal rotation in the same sense (as by means of a wrench applied to a hexagon or like head on at least one of the shafts).

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an elevation of a rotary drive with perpendicular axis adjustment: in accordance with the invention; and Figure 2 corresponds to Figure 1 but shows the drive after some adjustment of the position of the drive shaft axis has been effected.

In the drawings, a rotary drive comprises a drive shaft 18 carried by a support member 11 movable along a fixed guide 12, a rotary driven member 13, secured for rotation with the drive shaft, a rotary driving member 14 on a fixed axis 15, an endless transmission member 16 positively engaging both the driving and driven members 13, 14, a pair of idlers 17 also engaging the transmission member 16, with the driving member 14 engaging the transmission member 16 between the idlers 17, with the driving member 14 disposed nearer the driven member 13 than are the idlers 17, and with four straight runs of the transmission member 16 disposed one pair 16X between the driving member 14 and the idlers 17 and a longer pair 16Y between the driven member 13 and the idlers all parallel to the direction of movement of the support member 11 along the guide 12, a carrier 18 for the idlers 17, nut means 19 on the support member 11 and nut means 2 on the carrier, and screw means 21 extending betwen fixed bearings 22 and engaging with both nut means, screwthreads in the nut means 19 on the support member 11 having the same hand but twice the pitch of screwthreads in the nut means 2 on the carrier 18.

The fixed guide 12 is a frame having a pair of parallel side members 23 slidably engaged by shoes 24 on the support member 11, and cross-members 25A, 25B carrying the fixed bearings 22 for a pair of shafts 21 constituting the screw means and disposed one parallel to and adjacent each side member, the nut means being constituted by a pair of nuts 19 on the support member 11 and a pair of nuts 2 on the carrier 18, each shaft 21 having two screwthreaded portions 21A, 21B one of which engages the respective nut 20 on the carrier 18 while the other has a screwthread of the same hand but twice the pitch engaging the respective nut 19 on the support member 11, and the shafts 21 are coupled to each other by sprockets 26 and a chain 27 for simultaneous and equal rotation in the same sense by a wrench 28 applied to either of two hexagon heads 29 one on each shaft.

The rotary driving member 14 is indicated as being driven by a motor 3 through a gearbox 31, the endless transmission member 16 is a double-sided gear-belt, one side of which engages with teeth on the driving member 14 while the other side engages with teeth on the driven member 13, and the idlers 17 preferably also have teeth (not shown) engaging the belt.

The rotary drive shown in the drawings was invented for use with a carton transfer mechanism for packaging machinery, not shown but driven by the drive shaft 1, the axis 32 of which is required to be adjustable towards or away from a conveyor, also not shown but having its top cartonsupporting surface L level with the upper edges 33 of a pair of side-frames one of which constitutes the cross-member 25A, and below which level the axis 15 of the rotary driving member 14 is fixed at a distance A.

In Figure 1, the axis 32 of the drive shaft is indicated as being at a height Hl above the level L, while the axes 34 of the idlers are indicated as being at a depth D1 below the level L.

Clockwise rotation of the wrench 28 (as seen from above) results in simultaneous rotation of the shafts 21 (constituting the screw means) and simultaneous raising of the support member 11 (together with the drive shaft 18 and rotary driven member 13) and the carrier 18 (together with the idlers 17), but, because the screwthreaded portions 21B of the shafts 21 have twice the pitch of the screw threaded portions 21A, the support member 11 will rise by twice the amount by which the carrier 18 rises.However, because of the utilisation of a pair of idlers 17 and the four straight runs 16X, 16Y of the endless transmission member 16, as hereinbefore described, the differential movements of the support member 11 and carrier 18 will be accompanied merely by slight rotation of only the idlers 17 in opposite directions through equal angles as the straight runs 16X, 16Y of the transmission member change length, there being no phase shift of the driven member 13 and drive shaft 1 in consequence.

Figure 2 shows the rotary drive after the height of the axis 32 above the level L has been increased to H2 and it will be seen that the depth of the axes 34 below the level L has been decreased to D2 such that: H2-H1 = 2(Dl-D2).

It will also be seen that: 16X + 16Y after adjustment = 16X + 16Y before adjustment or: (D2 - A) + (H2 + D2) = (D1 - A) + (H1 + D1) Anti-clockwise rotation of the wrench 28 (as seen from above) will obviously have the opposite effect to that just described, and thus enables the spacing of the carton transfer mechanism from the conveyor to be adjusted, especially to suit different nominal heights of cartons.

Claims (8)

1. A rotary drive comprising a drive shaft carried by a support member movable along a fixed guide, a rotary driven member secured for rotation with the drive shaft, a rotary driving member on a fixed axis, an endless transmission member positively engaging both the driving and driven members, a pair of idlers also engaging the transmission member, with the driving member engaging the transmission member between the idlers, with the driving member disposed nearer the driven member than are the idlers, and with four straight runs of the transmission member between the idlers and the driving member and the driven member all generally parallel to the direction of movement of the support member along the guide, a carrier for the idlers, nut means on the support member, and nut means on the carrier, and screw means extending between fixed bearings and engaging with both nut means, screw threads in the nut means on the support member having the same hand but twice the pitch of screw threads in the nut means on the carrier, whereby, upon rotation of the screw means to move the support member and with it also the drive shaft and driven member perpendicular to their common axis, the carrier and with it also the idlers move in the same direction but by half the amount, these movements being accompanied merely by slight rotation of only the idlers in opposite directions as the straight runs of the transmission member change length, there being no phase shift of the driven member and drive shaft in consequence.

2. A rotary drive as in Claim 1, wherein the driving and driven members are transposed.

3. A rotary drive as in Claim 1 or Claim 2, wherein the fixed guide is a frame having a pair of parallel side members slidably engaged by shoes on the support member, and having cross-members carrying fixed bearings for a pair of shafts constituting the screw means, and disposed one parallel to and adjacent each side member, the nut means being constituted by a pair of nuts on the support member and a pair of nuts on the carrier, each shaft having two screwthreaded portions one of which engages the respective nut on the carrier while the other has a screwthread of the same hand but twice the pitch engaging the respective nut on the support member, and the shafts being coupled to each other for simultaneous and equal rotation in the same sense.

4. A rotary drive as in Claim 3, wherein the shafts are coupled to each other for simultaneous and equal rotation in the same sense by sprockets and a chain.

5. A rotary drive as in Claim 3 or Claim 4, wherein at least one of the shafts is provided with a hexagon or like head for application of a wrench.

6. A rotary drive as in any one of Claims 1 to 5, wherein the endless transmission member is a double-sided gear-belt, one side of which engages with teeth on the driving member while the other side engages with teeth on the driven member.

7. A rotary drive as in Claim 6, wherein the idlers also have teeth engaging the belt.

8. A rotary drive substantially as hereinbefore described with reference to the accompanying drawings.