US3871858A

US3871858A - Gob selectors with closed loop servo system

Info

Publication number: US3871858A
Application number: US415294A
Authority: US
Inventors: John Martin
Original assignee: Fabricacion de Maquinas SA de CV
Current assignee: Fabricacion de Maquinas SA de CV
Priority date: 1973-11-13
Filing date: 1973-11-13
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18

Abstract

For positioning the scoops of a gob selector machine, for example, of the type shown in U.S. Pat. No. 3,597,187, in place of the conventional direct coupled mechanical rotary or oscillatory systems, a hydraulic power boosting system using a programmed pilot stage is used. A contoured cam drives the booster stage through a sensing servo-valve in order to remove heavy mechanical forces from the cam, greatly increase the useful life of the drive system and permit higher speed operation.

Description

United States Patent Martin Mar. 18, 1975 GOB SELECTORS WITH CLOSED LOOP SERVO SYSTEM Primary Emminer-S. Leon Bashore Assistant Examiner-Frank W. Mi a [75] Inventor: gz Mamn Monterrey Attorney, Agent, 0r,Fi'rm-Kemon, Palmer &

exlco Estabrook [73] Assignee: Fabricacion de Maquinas, Monterrey, N.L., Mexico [57] ABSTRACT Filedl 1973 For positioning the scoops of a gob selector machine.

[2]] App} 415,294 for example, of the type shown in US Pat. No. 3,597,187, in place of the conventional direct coupled mechanical rotary or oscillatory systems, a hydraulic U-S- Cl. power boosting ystem using a programmed tage Int- - is used A contoured cam drives the booster tage [58] Field of Search 65/304; 91/392, 358 through a Sensing Serv0 va|ve in Order to remove heavy mechanical forces from the cam, greatly inl l References Cited crease the useful life of the drive system and permit UNITED STATES PATENTS higher speed operation. l,823,062 9/l93l Pleukharp CI 21] X 3 Claims, i g Figures 3,597,187 8/197] Trudeau 65/304 pmgmgnmlems I 3,871,858

sum 1 or 3 r HQZ PATENTEU 3,871 .858

Suzi-12053 GOB SELECTORS WITH CLOSED LOOP SERVO SYSTEM BACKGROUND OF THE INVENTION AND CROSS REFERENCE TO RELATED ART to one of a plurality of pairs of chutes extending downwardly to pairs of mold cavities arranged in a straight line. The firing order" for example, for eight pairs of cavities might be I, 5, 4, 8, 3, 7, 2, 6, etc. The means directing the molten glass gobs to the desired chutes is a pair of rotatably mounted scoops the upper ends of which remain coaxially aligned with the orifices of the gob former and are oscillated on axes co-axial with the orifices to feed the chutes in the desired firing order. The means for oscillating the scoops as taught in the aforementioned patent includes a rotatable cam and cam follower arrangement, the cam follower being mounted on an oscillatory member carrying a pair of ring gear segments in mesh with pinions carried by shafts mounting the scoops. While this arrangement is effective, there is considerable wear on both the cam and follower member due to loads and the ambient temperatures involved. Also, the amount of power required to drive the cam is quitelarge and consequently a sizable primer mover is required for the purpose. All of these factors tend to limit the speed of operation.

An additional problem in apparatus of the prior art type occurs whenever there is difficulty with one or more of the molding machines. If the gob selector is permitted to continue operating it means that the mo]- ten glass dispersed to the molding machine which is malfunctioning will be wasted. If common glass is being poured there is no problem but if leaded glass is involved it first becomes a factor of considerable financial magnitude because such glass cannot be collected and reheated to produce glass of the same quality. What is required is a change of cams to prevent dis pensing by the gob selector to the malfunctioning machine. Unfortunately, with machines of the prior art changing the cam is an operation of major proportions requiring substantially a whole working day.

BRIEF SUMMARY OF THE INVENTION The present invention substitutes for the cam and follower direct drive arrangement of the prior patent, a servo-hydraulic booster arrangement which reduces cam loading to an insignificant value, greatly prolongs the life of the apparatus as a whole, and permits increased speed of operation.

In addition, by simply removing two bolts, the cam of the present inventioncan be very quickly changed to prevent waste of expensive glass in the event of malfunction of one or more of the molding machines being fed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the oscillating scoops of the present invention together with some of the glass guiding chutes;

FIG. 2 is a side elevation partially in section of the apparatus shown in FIG. 1;

' FIG. 3 is a rear elevation of the apparatus shown in FIG. I; 7

FIG. 4 is a partial section on the lines 4-4 of FIG.

' FIG. 5 is a sectional view of the lines 5-5 of FIG. 2;

and

FIGS. 6, 7, and 8 are diagrammatic views useful in describing the operation of the servo booster system.

DETAILED DESCRIPTION OF THE DRAWINGS The scoops l0 and 12 shown in perspective view in FIG. 1 are mounted on shafts l4 and 16 respectively which extend through the upper wall of the housing 18 which encloses the components of the hydraulic servo booster system as well asthe gearing which interconnects the drive system and the scoop shafts. As in the aforementioned US. patent, the firing order" is determined by the cam or other pattern control member which controls the instantaneous position'of the shafts l4 and 16 and therefore of the scoops l0 and 12.

As shown most clearly in FIGS. 3 and 5, a pair of

pinion gears

20 and 22 are securedto the lower ends of shafts l4 and 16 respectively. A reciprocating piston 24 has two sets of rack teeth, 26 and 28 and the former engage with the pinion gears 20and 22, The longitudinal position therefore, of the piston 24 is what determines the position of the shafts 14 and I6 and their respective scoops l0 and 12.

The drive apparatus of the present invention employs a circular cam 30 continuously driven by a prime mover, not shown, through shaft 32. An arm 34 mounted for reciprocation parallel to piston 24 carries at one end, a roller cam follower 36 which is always in engagement with periphery of the cam 30. Substantially at the mid-section of the reciprocating arm 34, there is a pinion gear 38 mounted for free rotation on an axis which is at right angles to the axis of reciprocation of the arm 34. v

As shown most clearly in FIG. 2, another reciprocating arm 40 which is parallel to and spaced vertically upwardly from the arm 34 carries on its undersurface a set of rack teeth 42. The

teeth

28 and 42 of the piston 24 and arm 40 respectively, mesh with the teeth on the pinion gear 38 on opposite sides thereof.

The left hand end of the arm 40 as viewed in FIG. 2 is connected to drive a spool valve, the housing for which is indicated at 44, in FIG. 2. This valve is inter connected with and controls the fluid pressure in the space at opposite ends of the piston 24 in a manner which will be described with reference to the diagrammatic showing of FIGS. 6, 7 and 8.

In FIGS. 6, 7 and 8 the spool valve 44 is shown as including a valve rod 46 carrying a pair of

valve members

48 and 50. FIG. 6 illustrates the neutral position of the servo system in which fluid flow either into or out of the

chambers

52 and 54 at opposite ends of the piston 24 is blocked. This means that the piston 24 is effectively locked in the position shown in this figure and consequently the spouts are also locked because they are geared to the piston 24 through the

pinions

20 and 22 on the lower end of shafts l4 and 16. A biasing force is applied to the valve rod 46 from the member 40 by means of a spring 56 the exact location of which is shown in FIG. 2. FIG. 7 shows the parts in a position which would not actually be achieved in practice but which will help to describe the operation of the system. Referring to FIG. 7, the cam 30 has rotated clockwise to a position where the radius R2which is shorter than the radius R1 is presented to the cam follower 36. The spring 56 urges the spool valve to the left and also forces the cam follower 36 to remain in contact with the cam because the member 24 remains locked in the position shown in FIG. 6.

With the valve in the position shown in FIG. 7, fluid pressure will be applied to the right hand end of piston 24 causing it to move to the left as shown in FIG. 8 and rotating the two

pinion gears

20 and 22 in a clockwise direction. At the same time, the gear 38 is rotated in a counter clockwise direction which in turn moves the member 40 to the right which moves the spool valve back toward the neutral position of FIG. 6.

The foregoing description is not entirely accurate, but serves to illustrate the basic relationships between the various moving parts of the system. In actual practice, the spool valve would never reach the extreme position illustrated in FIG. 7 because as soon as it begins to move to the left, the ports communicating with opposite ends of the-pistons 24 would be cracked open and the piston24 would almost instantaneously begin moving to the left thereby initiating movement tending to keep the spool in neutral position. As those skilled in the art will readily recognize, the above described interconnection between the piston 24 and the piston 40 which always tends to return the spool valve to its initial position means that this is a closed loop hydraulic servo system. The only load on the cam 30 is that necessary to operate the spool valve 44 and the actual movement of the scoops is effected by hydraulic pressure acting on opposite ends of piston 24.

While a preferred embodiment has been herein shown and described, applicant claims the benefit'of a full range of equivalents within the scope of the appended claims.

I claim:

I. Apparatus for simultaneously distributing a pair of mold charges being fed from a double orifice glass feeder to the double cavity blank molds of a plurality of glass forming machines comprising a pair of elongated, curved deflector scoops, means supporting said scoops in generally side by side relationship, each scoop being formed with an open, upwardly facing receiving end in co-axial alignment with one of the feeder orifices only and a lower end, a pair of rotatably mounted shafts one rigidly attached to each of said scoops repectively each of said shafts having a pinion gear rigidly attached thereto;

gear means engaged with said gears and movable to rotate said shafts in synchronism;

fluid pressure means for moving said gear means in opposite directions depending on the direction of application of fluid pressure;

valve means for controlling the admission of fluid under pressure to said fluid pressure means; continuously rotatable cam means for controlling the position of said valve; and

means interconnecting said cam means, said fluid pressure means said gear means and said valve in a closed loop servo system so that any movement of said gear means in response to movement of said valve means tends to return said valve means to its initial position.

2. Apparatus as defined by claim 1 in which said gear means comprises a first rack mounted for reciprocating movement and terminating at opposite ends in pistons received within fluid filled cylinders, said fluid pressure means is a source of fluid under pressure and said interconnecting means includes a second rack parallel to and spaced from said first, a reciprocating arm parallel to said racks driven by said cam and carrying a pinion gear meshing with both racks and a link between said second rack and said valve.

3. In gob selector apparatus of the type which operates in conjunction with a molten glass feeder having a plurality of bottom outlet orifices from which separate mold charges are discharged simultaneously and which includes means for distributing charges for delivery by gravity to plural cavity-blank molds of a series of machines, plural mold charge deflecting scoops equal in number to the number of said orifices, said scoops being supported in such a position that each scoop extends from beneath one of said orifices and is movable selectively into alignment with said charge distribution means, the upper end of each scoop always being coaxially aligned with and beneath its respective orifice, means for oscillating said scoops in step by step fashion said means comprising:

a pair of rotatably mounted shafts, one rigidly connected to each of said scoops and extending downwardly therefrom parallel to each other;

a pair of gears, one rigidly attached to each of said shafts respectively;

,a first rack member having teeth in mesh with both said gears and mounted for reciprocating movement to effect rotation of said shafts and consequent positioning of said scoops, said rack having pistons at each end received within fluid filled cylinders;

a second rack mounted for reciprocating movement parallel to and spaced vertically from said first rack;

an arm mounted for reciprocation between and parallel to said racks and having a gear rotatably mounted thereon and meshing with the teeth of both racks;

a rotatably driven cam for continuously changing the position of said arm with respect to said racks; and

a spool valve connected to be reciprocated by said second rack and having a first pair of ports, one connected to each of said cylinders respectively, said spool being such as to simultaneously close and open said ports, said valve also having an inlet port between said first pair of ports affording connection to a source of fluid under pressure and a pair of interconnected outlet ports spaced outwardly of said first pair of ports.

Claims

1. Apparatus for simultaneously distributing a pair of mold charges being fed from a double orifice glass feeder to the double cavity blank molds of a plurality of glass forming machines comprising a pair of elongated, curved deflector scoops, means supporting said scoops in generally side by side relationship, each scoop being formed with an open, upwardly facing receiving end in co-axial alignment with one of the feeder orifices only and a lower end, a pair of rotatably mounted shafts one rigidly attached to each of said scoops repectively each of said shafts having a pinion gear rigidly attached thereto; gear means engaged with said gears and movable to rotate said shafts in synchronism; fluid pressure means for moving said gear means in opposite directions depending on the direction of application of fluid pressure; valve means for controlling the admission of fluid under pressure to said fluid pressure means; continuously rotatable cam means for controlling the position of said valve; and means interconnecting said cam means, said fluid pressure means said gear means and said valve in a closed loop servo system so that any movement of said gear means in response to movement of said valve means tends to return said valve means to its initial position.

3. In gob selector apparatus of the type which operates in conjunction with a molten glass feeder having a plurality of bottom outlet orifices from which separate mold charges are discharged simultaneously and which includes means for distributing charges for delivery by gravity to plural cavity-blank molds of a series of machines, plural mold charge deflecting scoops equal in number to the number of said orifices, said scoops being supported in such a position that each scoop extends from beneath one of said orifices and is movable selectively into alignment with said charge distribution means, the upper end of each scoop always being co-axially aligned with and beneath its respective orifice, means for oscillating said scoops in step by step fashion said means comprising: a pair of rotatably mounted shafts, one rigidly connected to each of said scoops and extending downwardly therefrom parallel to each other; a pair of gears, one rigidly atTached to each of said shafts respectively; a first rack member having teeth in mesh with both said gears and mounted for reciprocating movement to effect rotation of said shafts and consequent positioning of said scoops, said rack having pistons at each end received within fluid filled cylinders; a second rack mounted for reciprocating movement parallel to and spaced vertically from said first rack; an arm mounted for reciprocation between and parallel to said racks and having a gear rotatably mounted thereon and meshing with the teeth of both racks; a rotatably driven cam for continuously changing the position of said arm with respect to said racks; and a spool valve connected to be reciprocated by said second rack and having a first pair of ports, one connected to each of said cylinders respectively, said spool being such as to simultaneously close and open said ports, said valve also having an inlet port between said first pair of ports affording connection to a source of fluid under pressure and a pair of interconnected outlet ports spaced outwardly of said first pair of ports.