Shear mechanism for glassware forming machine

Abstract: A shear mechanism has a pair of shear assemblies mounted on parallel guide rails for reciprocating displacement controlled by a rack and pinion assembly having a rack driving each shear assembly. The racks are parallel and horizontally spaced and their movement paths substantially intersect the centre of mass of the shear assemblies.

Description: Individual section glassware forming machines form glassware from discrete gobs of molten glass. Vertically depending runners of molten glass are fed to a shear mechanism which severs the runners to form these gobs. Shear mechanisms may operate at 200 cycles per minute with one or more runners being hit by opposed shear blades to sever the runners every cycle. It is accordingly very difficult to achieve the degree of smoothness of operation that is desired. As shown in U.S. Patent Numbered 4,214,497 and 4,699,643 the opposed shear blade assemblies are both driven at the same side where the elongated guide rail supports ride on vertically spaced guide rails extending between the front and rear walls of the frame of the shear mechanism. The opposed shear blade assemblies are driven by horizontally related rack and pinion means, with two racks driving the two shear blade assemblies. It is an object of the present invention to provide an improved shear mechanism where the forces which reciprocate the opposed shear assemblies are substantially in line with the centre of mass of the driven assembly. The invention generally comprises a shear mechanism for shearing discrete gobs from at least one runner of molten glass comprising a frame, including front and rear walls interconnecting opposed sides, a pair of guide rails extending between the walls proximate the sides of the frame, a centreline extending parallel to the guide rails and located centrally there between, one shear blade assembly mounted for reciprocating movement along the guide rails, the assembly including an elongated guide rail support operatively associated with one of the guide rails and the centre of mass of the one shear blade assembly being located on one side of the centreline of the frame, a second shear blade assembly mounted for reciprocating movement along the guide rails, the second assembly including an elongated guide rail support operatively associated with the other guide rail and the centre of mass of the second shear blade assembly being located on the other side of the centreline of the frame, horizontally related rack and pinion means including first rack means connected to the one shear blade assembly and displaceable along an axis substantially intersecting the centre of mass of the one shear blade assembly, and second rack means connected to the second shear blade assembly and displaceable along an axis substantially intersecting the centre of mass of the second shear blade assembly. Other objects and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings of a preferred embodiment incorporating the invention Referring to the drawings : Figure 1 is a top view of a portion of a shear mechanism made in accordance with the teachings of the present invention; and Figure 2 is a view taken at 2-2 of Figure 1; Figure 3 is a view taken at 3-3 of Figure 1; Figure 4 is an oblique view of a drop guide assembly; Figure 5 is a view taken at 5-5 of Figure 6; Figure 6 is an enlarged view of a portion of Figure 1, with the shear removed; Figure 7 is a front view of the drop guide connecting plate; Figure 8 is an elevational cross sectional view of the tensioning assembly; Figure 9 is a view taken at 9-9 of Figure 8 showing the indexing wheel operatively associated with an indexing shaft; Figure 10 is an end view of the shear mechanism showing the control knobs; Figure 11 is a view taken at 11-11 of Figure 1; and Figure 12 is an exploded view of the quick release support bearing shown in Figure 1. The shear mechanism has pairs (two in the illustrated embodiment) of opposed upper 10 and lower 11 shears which are supported for reciprocating displacement within a frame 12 comprising side walls interconnecting a front wall 13 and a rear wall 15. A pair of guide shafts 14 extend along either side of the frame and slidably support the upper blade assembly 16 which includes a shear assembly housing 18 and an elongated tubular guide shaft support 20 and a lower shear assembly housing 19 having a guide shaft support 21. The housing 18 is secured at one side via screws 22 to the guide shaft support 20 and is slidably interconnected with the lower guide shaft 14 by a bearing support 24. Associated with each upper shear blade 10 is a drop guide 26. The position of each drop guide 26 is independently changeable laterally from side to side (transverse displacement) and forwardly and rearwardly (longitudinal displacement) relative to the shear blade 10. Rotation of the associated longitudinal displacement knob 28 will result in the longitudinal displacement of the drop guide 26 and the rotation of an associated transverse displacement knob 30 will result in the transverse displacement of the drop guide. Rotation of the transverse displacement 30 knob rotates a shaft 32 and attached drive gear 34 (Figure 2) which via an idler 36 rotates a driven gear 38 secured to a drive shaft 39 having a bore 40 which is square in cross section. The longitudinal displacement drop guide knob 28 is connected to a drive shaft 42 which also has a square bore 40. A hex surface 44 is defined on the shaft outer diameter which operates together with a spring 46 supported by a block 47 to define a detent to hold the shaft at a desired orientation. Also secured to the frame 12 is a block 50 (Figure 3) supporting a spring 52 which is operatively associated with an enlarged fine toothed wheel 54 which is secured to the gob guide transverse displacement shaft 32 so that lateral adjustments can be made in fine increments. As can be seen from Figure 3 each of the drop guide drive shafts 39, 42 receives a driven shaft 60,61 which extends rearwardly from the shear assembly housing 18 and which has a matching square cross section. The length of both the drive shafts and the driven shafts is selected so that they will be operatively associated throughout the displacement of the shear assembly housing 18. Each drop guide assembly (Figure 4) includes a base 62 having opposed transverse top flanges 63 which defines a slide surface 64 supporting and guiding the lateral displacement of the gob drop guide support block 66 to which the drop guide 26 is secured. The slide includes a lateral groove 68 which receives a rack 70 secured to the bottom of the block 66 and driven by a pinion 72 (Figure 5) secured to the end of the drop guide transverse displacement driven shaft 60. The block has a laterally extending opening 74 which is partially defined by opposed inwardly extending shelves 76 for capturing the base flanges 63. The front threaded end of the drop guide longitudinal displacement driven shaft 61 (Figure 6) has a threaded portion 80 which is coupled to a nut 81 carried by cross link 82 which is connected to a pair of rods 84 slidably supported within the housing 18 for relative axial displacement. The base 62 of the drop guide is secured to these rods so that rotation of the control knob 28 will advance or retract the drop guide. A notch 86 is defined near the front end of these rods (Figure 7 and the front end of the drop guide transverse displacement driven shaft 60 has an annular groove 88 which are captured by the bottom surface of a connecting plate 90 and a cut out 89 when the plate is shifted to the latching position shown in Figure 7. When the connecting plate is released by loosening a pair of screws 92 which pass through enlarged plate holes 94 and which are received by the drop guide base 62 and shifted to the right so that the plate becomes spaced from the lower left rod 84 and so that a large cut out 98 is adjacent and spaced from the lower right rod 84 and the cut out 89 is spaced from the shaft 60, the entire drop guide assembly can be pulled off the three rods and replaced with another assembly. The pinion 72 (Figure 5) is secured with a screw 95 to the pinion shaft 60 and the front end of the shaft is supported by a bearing 96 which is press fit within a base opening. A rear opening 99 of the base is large enough so that when the base is released it can be completely pulled from the pinion and supporting shaft. The shear housing 18 of the upper blade assembly 16 supports the two shear blades 10 which are to extend above the opposed shear blades 11 of the lower shear blade assembly 19 when the shear blades are conjointly displaced to the advanced position. They are to frictionally engage each other with a selected force or tension and the tensioning assembly is illustrated in Figure 8. One upper shear blade 10 is secured by screws 100 to a three piece mounting block 102. A control shaft 104 which is rotatably supported within suitable bearings 106 has a threaded portion 108 at one end which is received by a threaded bore 110 in the mounting block 102. Rotation of the control shaft either elevates or lowers the shear blade to control the desired tension between the upper and lower blades. The other end of the control shaft has a bevel gear 112 which is driven by a bevel gear 114 secured to rotatable rod 115. An indexing wheel 116 is also attached to the rod 115. As can be seen from Figure 9, this indexing wheel 116 will be indexed one pitch each complete revolution of a tensioning drive shaft 118 which has a single tooth 119 and a spring detent 120 will hold the index wheel at any set location. The tensioning drive shaft 118 is rotatably supported by a mounting sleeve 121 secured to a back plate 124 and changes are made by rotating a control knob 125. As can be seen from Figures 1 and 10, the control structure, i.e., the structure from the control knobs 28, 30, and 125 to their drive shafts 39, 42, 118 is mounted on the back plate 124 of the frame 12 which is secured to the frame 12 by a plurality of screws 126. A pair of cylindrical bushings 128 are secured to the back plate for slidably receiving a cylindrical dowel and a diamond pin dowel 131 which are secured to the frame. A removable stop 132 is secured to the end of the cylindrical dowel once the back plate has been placed in position and secured to the frame. If the shears have to be replaced, the back plate assembly is released and pulled rearwardly until the back plate bushing 128 engages the stop 132. The upper shear assembly is moved forwardly to its advanced position. This relative movement separates the back plate drive shafts 39, 42 from the gob guide driven shafts 60, 61. As shown in Figures 1 and 11, the upper shear housing 18 is supported at one side on top of the guide shaft support 20 (spaced flanges 127 rest on horizontal support surface 129 and a vertical rib 133 is received by a suitable slot 135) and is secured in position by the screws 22 (a dowel 137 is used to assure proper location). The guide shaft support 20 is secured to a frame 138 which is connected to a drive rod 270 (Figure 1). The quick release support bearing 24 (Figure 12) has an upper finger 142 and a lower finger 144. The upper finger sits on a shelf 146 defined on the shear housing 18 and is not free to rotate. A screw 148 passes through enlarged holes 149, 150 in the upper finger and the shelf and threadedly engages a threaded bore 151 in the lower finger 144. The lower finger has an arcuate slot 152 which corresponds to a segment of a circle having a centre coincident with the axis of the threaded hole 151 and a pin 153 secured to the shelf extends vertically downwardly parallel to the screw 148 into this slot. When a mechanic loosens the screw 148, the lower finger 144 will rotate counter-clockwise until the pin 153 engages one end of the slot 152. At this position the lower finger 144 will be rotated 90° clear of the guide shaft 14 and the shear housing 18 can be removed. When another shear housing is placed in position and the screw 148 is tightened, the lower finger 144 will rotate clockwise until the pin 153 hits the other end of the slot 151 locating the lower finger in the support position. Further tightening of the screw will clamp the fingers to the arm defining a bearing surface between a horizontal flat bottom surface 154 of the upper finger and a flat top 155 of the guide rail 14 and between a top flat horizontal surface 156 on the lower finger and a flat bottom surface 157 of the guide rail. The lower shear assembly housing 19 has an arm 222 including an elongated tubular portion 224 for slidably receiving one of the guide shafts 14 and a support bearing 226 to guide the other guide shaft 14. Blade mounting blocks 228 are secured to a mounting plate 230 which is secured to the arm by a pair of screws 232 and the shear blades 11 are secured to these blocks. To change the configuration of the machine from double gob to triple gob, for example, the mounting plate screws 232 of the lower shear assembly are removed. The mounting plate assembly is replaced with a mounting plate assembly having three blades. (Screw receiving holes are provided in the arm to receive the mounting plate screws of each mounting plate assembly.) Additionally, the upper shear blade housing and back plate assembly are removed and replaced with a shear blade housing and back plate assembly having the desired configuration. Since shear blade tensioning and gob drop guide adjustments all can be made from the rear end of the frame, the shear drive mechanism can be centrally located at the front end of the frame. The shear assemblies are driven by displaceable rods 270, 271 which have racks 272 secured thereto to be driven by a pinion 274 which is secured to the output shaft 275 of a servo motor 276. The drive rods 270, 271 lie in a horizontal plane (the shears also move in a horizontal plane) so that they will lie on either side of the centreline 278 of the frame. In the lower shear blade assembly which supports the lower shears 11 the elongated guide shaft support 21 rides along the lower guide rail and the centre of mass of the reciprocating shear assembly is below the centreline substantially in line with the lower shear assembly drive rod 271. The upper guide rail support 20 and the frame 138 interconnecting the upper drive rod 270 and the upper guide rail support all lie near the upper guide rail 14 and accordingly, the centre of mass of the upper shear assembly from the frame 138 to the quick release bearing support 24 lies above the centreline substantially in line with the upper rod 270.

Claims: A shear mechanism for shearing discrete gobs from at least one runner of molten glass comprising a frame (12), including front (13) and rear (15) walls interconnecting opposed sides, a pair of guide rails (14) extending between said walls proximate the sides of said frame, a centreline (278) extending parallel to said guide rails and located centrally there between, one shear blade assembly (16) mounted for reciprocating movement along said guide rails, said assembly including an elongated guide rail support (20) operatively associated with one of said guide rails and the centre of mass of said one shear blade assembly being located on one side of said centreline of said frame, a second shear blade assembly (19) mounted for reciprocating movement along said guide rails, said second assembly including an elongated guide rail support (21) operatively associated with the other guide rail and the centre of mass of said second shear blade assembly being located on the other side of said centreline of said frame, horizontally related rack (272) and pinion (274) means including first rack means (272) connected to said one shear blade assembly (16) and displaceable along an axis substantially intersecting the centre of mass of said one shear blade assembly, and second rack means (272) connected to said second shear blade assembly (19) and displaceable along an axis substantially intersecting the centre of mass of said second shear blade assembly (19). A shear mechanism according to claim 1, wherein said rack and pinion means includes a pinion (274) secured to the rotating output shaft (275) of a servo motor (276) and located between and operatively engaging said first and second rack means (272). A shear mechanism according to claim 1, wherein the shear blade assembly (16) remote from said rack (272) and pinion (274) means comprises at least one vertically displaceable shear blade (10), and a corresponding number of adjustable drop guide assemblies (26). A shear mechanism according to claim 1 wherein said rack (272) and pinion (274) means includes a pinion (274) rotatable about an axis selectively located on said centreline between and operatively engaging said first and second rack means.

Inventors: MENARD ALAN, PINKERTON STEVEN J, MENARD, ALAN, PINKERTON, STEVEN J.
Applicants: EMHART GLASS MACH INVEST, EMHART GLASS MACHINERY INVESTMENTS INC.
Application year: 1992
Main classification: C03B7
IPC codes: C03B7