US 3920131 A
A loader assembly for sequentially delivering workpieces to a grinding station of a machine tool, wherein the loader assembly includes a loader arm which is displaced in a first direction from a retracted position to a pick up station and then to a grinding station, and which is displaceable in a reverse direction from the grinding station to the retracted position. The loader arm is hydraulically displaced from the pick up station to the grinding station and from the grinding station to the retracted position, but is displaced from the retracted position to the pick up station by a compression spring which is selectively compressed during displacement of the loader arm in the reverse direction.
Description (OCR text may contain errors)
United States Patent 1191 1111 3,920,131 Gebel  Nov. 18, 1975 1 1 LOADER ASSEMBLY FOR A MACHINE 3,640,026 2/1972 Flanigan 214/1 BD x TOOL 3,780,885 12/1973 Van Der Roer 214/1 Bo x Inventor: Kurt M. Gebel, Waynesboro, Pa.
Landis Tool Company, Waynesboro, Pa.
Filed: Nov. 7, 1974 Appl. No: 521,786
US. Cl 214/1 BD; 214/1 PB Int. Cl. B23B 15/00 Field of Search.... 214/1 BC, 1 R, 1 BD, 1 BH, 214/1 P, 1 BV, 1 PB, 8.5 K, 147 T; 198/20 R, 27; 51/215 R References Cited UNITED STATES PATENTS 5/1961 Kent 214/1 BD 9/1961 Dixon et a1.... 9/1962 Kralowetz 214/1 P 214/1 BDv Primary Examiner-Frank E. Werner Attorney, Agent, or FirmSpencer T. Smith  ABSTRACT A loader assembly for sequentially delivering workpieces to a grinding station of a machine tool, wherein the loader assembly includes a loader arm which is displaced in a first direction from a retracted position to a pick up station and then to a grinding station, and which is displaceable in a reverse direction from the grinding station to the retracted position. The loader arm is hydraulically displaced from the pick up station to the grinding station and from the grinding station to the retracted position, but is displaced from the retracted position to the pick up station by a compression spring which is selectively compressed during displacement of the loader arm in the reverse direction.
4 Claims, 3 Drawing Figures U.S. PEltfiIlt Nov. 18, 1975 Sheet10f2 3,920,131
US. Patent Nov. 18, 1975 shw 2 of2 3,920,131
LOADER ASSEMBLY FOR A MACHINE TOOL The present invention relates to loader assemblies for sequentially feeding workpieces to thegrinding station of a grinding machine.
Conventionally the displacement of a loader through a predetermined cycle is controlled by a cylinder or cylinders which will positively, selectively displace the pivot arm from a retracted position 'to a pick up'station, from the pick up station to a grinding station, and from the grinding station back to the retracted position. The hydraulics required is complex and it is accordingly an object of the present invention to simplify the structure for achieving the desired displacement of the loader through this cycle;
Other objects and advantages of the present invention will become apparent from the following portion of this specification and from the accompanying drawings which illustrate in accordance with the mandate of the patent statutes a presently preferred embodiment incorporating the principles of the invention.
Referring to the drawings:
FIG. 1 is an elevational view of a loader assembly made in accordance with'the teachings of the present invention for a cylindrical grinding machine.
FIG. 2 is a perspective view of a portion of the loader assembly illustrated in F IG. 1; and
FIG. 3 is a cross-sectional view of another portion of the loader assembly illustratedin FIG. 1.
upon inclinded rails 10, 12, which are secured to side frames 14, 16 of the loader assembly base 18. These rails 10, 12 terminate at a pick up station 20, where they engage a pair of stops 22, 24, which are also secured to the side frames l4, 16. The workpiecesW are sequentially fed by gravity to a start position 26 where a selected diameter 28 of the lead workpiece W abuts against the face 30 of the primary stop member 34 of the escapement mechanism 32.
The escapement mechanism 32 additionally includes a linkage arrangement 36, which is secured via a .first transverse rod 38 to the primary stop member 34 and via a second transverse rod 40 to a secondary stop member 42. The secondary stop member 42, which is lowered as the primary stop member 34 is elevated, prevents the trailing workpiece W from advancing to the pick up station when the lead workpiece W is released from engagement with the primary stop member 34. A released workpiece rolls downwardly along the rails until it abuts against the stops 22, 24 at the pick up station 20. The escapement mechanism is controlled by a selectively operated escapement cylinder 44 including a rod 46, which is joined via a link 48 to the first traverse rod 38. A rail stop 50 which is secured to the side of and thereby moves conjointly with the primary stop member 34 overlies a small diameter 52 of the released workpiece W when it arrives at the pick up station to prevent the workpiece W from bouncing off the inclined rails l0, 12.
The workpiece is carried from the pick up station 20 to the grinding station 54 of a cylindrical grinder (the abrasive wheel 56, and the base 60 of the cylindrical grinder being shown) by a loader mechanism 62 having spaced parallel arms 64 with workpiece receiving shoes 66 at the free ends thereof. The loader mechanism 62 and a spring compressing lever 68 are keyed to a shaft 70 which is rotatably mounted on the side frames 14,
'30 As illustrated in FIG. 1, workpieces W are positioned 2 16 of the base 18 and the conjoint rotative displacement thereof is controlled by a loader cylinder 72 which is connected to one end of the spring compressing lever.
A hook or jaw member 74 (FIG. 2) is pivotally mountedintermediate the loader arms proximate the free end thereof and the displacement thereof is controlled by a jaw member cylinder 76 which extends intermediate a support 78-extending outwardly from the loader arms and the remote endof the jaw member.
A spring loaded mechanism 80 is mounted on one of the side frames and includes a plunger cylinder 82 (FIG. 3), which is located within a bore 84 of the mechanism housing 86. A plunger plate 88 includes a plunger pin 90 which extends outwardly from the housing through an aperture 92 in the housing end cap 94. The spring loaded mechanism is selectively located so that the spring compressing lever 68 will engage the plunger 90 when the loader mechanism is at the pick up station and forcefully compress the compression spring 96 as the loader mechanism is pivotally displaced to the retracted position. The degree to which the compression spring will be compressed can be selectively varied by adjusting the adjustment screw 98.
In operation, depression of a cycle start button (not shown) energizes the escapement cylinder 44 to operate the escapement mechanism 32. The primary stop member 34 is accordingly elevated to release the lead workpiece W, while the secondary stop member 42 is lowered to retain the next workpiece W at its location. Depression of the cycle start button also energizes a timer (not shown), which times out after the passage of a period of time selected to permit the leading workpiece W to roll to the pick up station and, if desired, to be properly oriented at this location by an orienting mechanism 99 such as is disclosed in U.S. Pat. No. 3,863,402. When the timer times out, the three position loader valve or solenoid 72 is switched .to its neutral position, whereupon the compressed spring 96 can release thereby pivotally displacing the loader to the pick up station. The escapement cylinder 44 is at the same time retracted to its initial position to reset the magazine in its initial condition with a lead workpiece W located against the primary stop member 34.
When the pivot arm is advanced to the pick up station, the shoes 66 of the loader arms 64 abut against a selected diameter D of the workpiece W. A trip dog 100 mounted on the lever shaft 70 trips a first switch 102, which energizes the hook member cylinder 76, whereupon the hook or jaw will pivot into engagement with the small diameter 52 of the workpiece W. When the jaw is closed, a switch actuator 104, secured to the hook member cylinder, actuates a second switch 106 which energizes the loader cylinder 72 to pivotally displace the clamped workpiece W to the grinding station 54. A third switch 1 10 is tripped by a trip dog 1 12 when the loader arrives at the grinding station to energize the grinding machine center advance mechanism (not shown), whereby the workpiece will be engaged by the centers (not shown) whereupon the hook member cylinder will be actuated to open the jaw. When the jaw is fully retracted, a fourth switch 113 is closed by the switch actuator 104 mounted on the hook member cylinder to energize the loader cylinder 72 to retract the loader to the fully retracted position. A fifth switch is operated by a cam 122 mounted on the lever shaft 70 when the loader is in the fully retracted position to repeat the cycle.
What is claimed is:
l. A loader assembly comprising means for sequentially delivering a plurality of workpieces to a pick up station,
pivot arm means selectively pivotally displaceable about a predetermined pivot in a first direction from a retracted position whereat a workpiece can be delivered by said delivering means to said pick up station, to the pick up station whereat the delivered workpiece can be secured to said pivot arm means, to a grinding station whereat the secured workpiece can be suitably gripped by the centers of a grinding machine or the like and selectively, pivotally displaceable in the opposite direction from the grinding station to said retracted position,
means for pivotally displacing said pivot arm means from said grinding station to said retracted position,
spring means selectively compressible from a first predetermined size to a second compressed size,
said pivot arm means selectively engaging and compressing said spring means from said first predetermined size to said second compressed size as said pivot arm means is pivotally displaced in said opposite direction from said pick up station to said retracted position,
means for maintaining said spring means at said second compressed size while said delivering means delivers a workpiece to said pick up station,
means for releasing said maintaining means when a workpiece has been delivered to said pick up station whereby said pivot arm means will be pivotally 4 displaced from said retracted position to said pick up station,
means for securing a delivered workpiece to said pivot arm means when said pivot arm means is at said pick up station,
means for pivotally displacing said pivot arm means from said pick up station to said grinding station after a workpiece has been secured to said pivot arm means, and
means for releasing said securing means after said pivot arm means has been displaced to said grinding station.
2. A loader assembly according to claim 1, further comprising means for selectively varying the degree to which said spring means will be compressed as said pivot arm means is retracted to said retracted position.
3. A loader according to claimm 2, wherein said spring means comprises a housing including an internal chamber and an aper-' ture in one end thereof,
a plunger plate selectively configured for slidable displacement within said internal chamber, said plunger plate including a plunger pin selectively sized to pass through said aperture, and
spring means located within said housing internal chamber intermediate said plunger plate and an opposing end of said housing for urging said plunger plate into engagement with said one end.
4. A loader assembly according to claim 3, wherein said selectively varying means comprises means for varying the axial position of said plunger cylinder.