STRAIGHT LINE SHEAR MECHANISM

Abstract: A straight line shear mechanism has rack driven shears which are operated by a pneumatic cylinder. Opposite ends of the operating rod (23) of the pneumatic cylinder (24) are connected via couplings (28,48) which permit rotation of the rod about its axis and which automatically accommodate slight misalignments to minimize distortion of the rod (23).

Description: The present invention relates to a straight line shear mechanism for cutting gobs from continuously fed runners of molten glass which gobs are to be formed into glass containers. A straight line shear mechanism is disclosed in U.S. No. 4,699,643 and comprises a pair of opposed shears mounted on brackets for sliding movement towards and away from each other, means for moving the shears comprising a pneumatic cylinder having an operating rod extending outwardly from opposite ends of the cylinder, a rack and pinion assembly having at least one rack element, one end of the operating rod being connected to the rack element and the other to a bracket. The molten glass of the runners on which the shear mechanism operates distributes a tremendous amount of heat, which tends to cause distortion and misalignment of various components of the mechanism. In particular the operating rod tends to become distorted owing to misalignment of other components, and such distortion causes excessive wear which results in premature failure of the pneumatic cylinder thus to cause stoppage of the whole machine supplied with glass from the shear mechanism. It is one of the objects of the present invention to increase the operating life of such a shear mechanism. The present invention provides a straight line shear mechanism for cutting discrete gobs from a runner of molten glass which are to be formed into glass containers comprising a pair of opposed shears mounted on brackets for sliding movement towards and away from each other means for moving the shears comprising a pneumatic cylinder having an operating rod extending outwardly from opposite ends of the cylinder a rack and pinion assembly having at least one rack element one end of the rod being connected to the rack element and the other to a bracket characterized in that the connection between the ends of the rod and the rack element and the bracket are made by couplings each coupling comprising a head member fixed to the rod and a socket member fixed to each of the rack element and the bracket, the head member comprising a cylindrical head on a neck, the socket member comprising an axial slot extending from an end face of the socket member and adapted to receive the neck of the head member, and opening into a transverse slot adapted to receive the cylindrical head the dimensions of the coupling parts being so that the rod can rotate about its axis and slight misalignments between the rod the bracket and the rack element can be accommodated without distortion of the rod. There now follows, with reference to the accompanying drawings, a description of a preferred embodiment of a shear mechanism chosen to illustrate the invention by way of example. In the accompanying drawings Figure 1 is a diagrammatic plan view of a straight line shear mechanism. Figure 2 is an oblique view, with the parts separated, of a coupling between a rod of a pneumatic cylinder of the shear mechanism and a rack element, the teeth of the rack being shown upwardly facing rather than downwardly facing for the purposes of illustration. Figure 3 is a view of part of the straight line shear mechanism, partly in section, taken at line 3-3 of Figure 1. The straight line shear mechanism 10 is arranged to cut discrete gobs of glass (not shown) from gravity fed runners of molten glass (not shown) which gobs are to be formed into glass containers. The mechanism comprises pairs of opposed shears 11 which are mounted for cutting movement towards and away from each other. Each pair of shears 11 is secured to an L shaped slide 12 which is displaceable along parallel guide rails 14. The L shaped slides 12 have cylindrical portions 16 with integral brackets 18. The shears are moved by means comprising a pneumatic cylinder 24 having an operating rod 23 extending outwardly from both ends of the cylinder 24. A rack element 20 (Figure 2) of a rack and pinion assembly 22 is connected to one end of the rod 23 of the pneumatic cylinder 24 whose other end is connected to the left hand bracket 18, and an other rack element 20, which extends below the pneumatic cylinder 24, is directly connected to the other bracket 18. Each rack element is supported by a cylindrical housing 21. When the pneumatic cylinder 24 is operated, the shear pairs 11 will be conjointly displaced towards or away from each other. Connections between the ends of the rod 23 and the rack element 20 and the bracket 18 are made by couplings 28 (Figure 2) and 48 (Figure 3). The coupling 28 connects the rod 23 to the upper rack element 20 and is illustrated in Figure 2. It includes a cylindrical head member 30, a reduced diameter neck 32, a third cylindrical portion 34 approximately the same diameter as the head portion 30 and having flats 36 defined there to receive an installation tool, and an elongated threaded portion 38, which is threaded into a threaded bore 39 in one end of the rod 23 and by which the head member 30 is fixed to the rod 23. A cylindrical socket member 40 of a rack 20 has a vertical, upwardly opening axial slot 42 extending from an end face of the member 40. The width W of this slot is slightly larger than the diameter of the neck 32 to permit its placement in this slot. The slot 40 opens into a second vertical, upwardly opening slot 44 defined in the rack element transverselly behind the first slot 42. This slot 44 defines the axial length L1 of the front slot 42 (slightly smaller than the axial length L2 of the neck 32). The axial length L3 of the second slot 44 is also selected to be slightly larger than the axial width L4 of the head member 30 of the coupling 28. The desired orientation of these slots is maintained by the rack and pinion mechanism 22. A coupling 48, which connects the other end of the rod 23 to the bracket 18, is shown in Figure 3. A similar coupling 48 may connect a rack 20 to the other bracket 18. This coupling comprises a socket member 50 having the same first axial slot 42 and second transverse slot 44 defined therein, a bushing 52 which is received by a bracket opening 54 and a threaded end portion 56. The socket members 50 is secured to the bracket 18 by a thrust washer 60, a split nut 62 and a threaded collar 64. The coupling 48 connects the rod 23 to the bracket 18 and also comprises a head member 28′ comprising a cylindrical head member 30′ and a reduced diameter threaded portion 36′ which is threadedly inserted into a threaded bore 39 in the rod 23. A roll pin 66 can be used to secure the head member 28′ to the rod 23. In the coupling 48, the rod 23 provides a neck 32 which is received in the axial slot 42 while the head 30′ is received in the transverse slot 44. The rack and pinion gear box 22 is secured in position by six screws. Four of these screws 67 pass through a pneumatic cylinder mounting flange 68 and a side frame 70 into a gear box housing 72, and two additional screws (not shown) extend through the side frame 70 into the gear box housing 72. To disconnect the pneumatic cylinder 24, these six screws are removed so that the gear box housing 72 can be removed. The cylindrical rack housing 21 can then be retracted exposing the coupled end 40 of the rack 20. The right end of the pneumatic cylinder rod 23 can then be lifted separating the coupling 28 from the rack 20 (a hole 78 in the frame through which the rod 23 passes is sufficiently large to permit such movement). The left end of the rod 23 is then lifted to complete removal of the pneumatic cylinder 24. The couplings permit rotation of the rod 23 about its axis and automatically accommodate a small amount of misalignment from the bracket 18 to the rack 20, thereby minimizing rod distortion, and hence, rod wear.

Claims: A straight line shear mechanism for cutting discrete gobs from a runner of molten glass which are to be formed into glass containers, comprising a pair of opposed shears (11) mounted on brackets (18) for sliding movement towards and away from each other means for moving the shears comprising a pneumatic cylinder (24) having an operating rod (23) extending outwardly from opposite ends of the cylinder a rack and pinion assembly (22) having at least one rack element (20). one end of the rod (23) being connected to the rack element (20) and the other to a bracket (18) characterized in that the connection between the ends of the rod (23) and the rack element (20) and the bracket (18) are made by couplings (28, 48,) each coupling comprising a head member (30, 28′,) fixed to the rod (23) and a socket member (40, 50,) fixed to each of the rack element (20) and the bracket (18), the head member comprising a cylindrical head (30, 30′) on a neck (32), the socket member comprising an axial slot (42) extending from an end face of the socket member and adapted to receive the neck (32) of the head member, and opening into a transverse slot (44) adapted to receive the cylindrical head 30,30′, the dimensions of the coupling parts being so that the rod (23) can rotate about its axis and slight misalignments between the rod (23,) the bracket (18) and the rack element (20) can be accommodated without distortion of the rod (23). A mechanism according to claim 1, wherein the axial slots (42) and the transverse slots (44) are slightly larger than the necks (32) and the heads (30,30′) received in them. A mechanism according to one of claims 1 and 2, wherein the head member is removably fixed in the rod (23) by a threaded portion (28,28′) A mechanism according to claim 3, wherein the threaded portion (28′) is locked in the rod (23) by a transverse pin (66). A mechanism according to claim 3, wherein the head member comprises a portion of increased diameter (34) adjacent the neck (32).

Inventors: MENARD, ALAN W., WRIGHT, DOUGLAS W.
Applicants: EMHART GLASS MACHINERY INVESTMENTS INC.
Application year: 1990
Main classification: C03B7
IPC codes: B26D1, C03B7