Hydraulic control circuit for loader of thin-wall spline rolling machine

A hydraulic control circuit (10) for operating a loader (12) of a machine for splining an annular thin-wall sleeve of a power transmission member is disclosed as including valving (116) for communicating supply and return conduits (102,116) with load and unload cylinders (14,16) to provide loading and unloading movements. Load and unload valves (118,120) of the valving have load cycle positions where the load cylinder drives both the loading and unloading members (26,28) which clamp a thin-wall member during such movement to provide loading thereof for splining. In an unload cycle position of the valves, both the load and unload cylinders are hydraulically driven in an unloading direction opposite to the loading movement. The loading and unloading members (26,28) are moved away from each other by their associated cylinders in an index cycle of the valves to permit indexing of a load table (30) under the operation of an index valve (162) of the circuit.

TECHNICAL FIELD 
This invention relates to a hydraulic control circuit that operates a 
loader for a machine having apparatus for splining an annular thin-wall 
sleeve of a power transmission member. 
BACKGROUND ART 
U.S. Pat. No. 3,982,415, which is assigned to the assignee of the present 
invention, discloses a machine having apparatus for splining an annular 
thin-wall sleeve of a power transmission member by meshing die and mandrel 
teeth with the sleeve located therebetween such that the resultant forming 
thereof provides the splines. This spline forming process takes place in a 
rolling manner as a toothed mandrel on which the power transmission member 
is mounted rotates upon movement of toothed dies in opposite directions on 
opposite sides of the mandrel to provide the tooth meshing. An end wall of 
the power transmission member is clamped against an end of the mandrel 
during the splining process so as to insure precise forming of the 
resultant splines. Clutch hubs for automatic transmissions of road 
vehicles is one usage for which this spline forming process has particular 
utility in replacing prior impacting operations used to form clutch hub 
splines, as is discussed in the aforementioned patent. 
U.S. Pat. No. 4,155,237,which is also assigned to the assignee of the 
present invention, discloses apparatus for automatically loading and 
unloading power transmission members on a toothed mandrel for splining of 
thin-wall sleeves thereof by meshing of the die and mandrel teeth in the 
manner discussed above. Loading and unloading members driven by associated 
hydraulic cylinders are provided to cooperatively clamp and move power 
transmission members to be splined from a load table toward and away from 
the mandrel. Both cylinders are hydraulically driven during the loading 
movement toward the mandrel and during the unloading movement away from 
the mandrel back toward the load table. After movement of the splined 
power transmission member back to the load table, the loading and 
unloading members are moved away from each other to permit indexing of the 
load table for alignment of another member to be splined with the loading 
and unloading members. 
DISCLOSURE OF INVENTION 
The present invention provides a novel hydraulic control circuit for 
operating a loader for loading and unloading thin-wall power transmission 
members on a toothed mandrel for splining thereof by a pair of toothed 
dies upon meshing of die and mandrel teeth with the thin-wall member 
between the meshing teeth. 
The loader operated by the hydraulic control circuit of the invention 
includes a load table for indexing thin-wall members into alignment with 
the mandrel for loading thereof and for receiving the splined thin-wall 
members after the splining operation. Loading and unloading members of the 
loaders are respectively connected to pistons of load and unload cylinders 
and cooperate to move thin-wall members from the load table to the mandrel 
for splining and subsequently from the mandrel back to the load table 
after the splining. A rotatable clamp of the loading member cooperates 
with the unloading member during the loading movement to clamp the 
thin-wall member therebetween and cooperates with the mandrel to clamp the 
thin-wall member during the splining operation. 
The hydraulic control circuit of this invention operates the load and 
unload cylinders to move the loading and unloading members during the 
loader operation. A high pressure supply conduit of the circuit feeds 
pressurized hydraulic fluid from a pump to the cylinders, and a low 
pressure return conduit of the circuit receives hydraulic fluid from the 
cylinders. Valving of the control circuit communicates opposite sides of 
the load and unload cylinder pistons with the conduits. The valving has a 
load cycle position where the load cylinder piston is hydraulically driven 
to move the loading member from the load table toward the mandrel while 
moving the unloading member with a thin-wall member to be splined clamped 
between the clamp of the loading member and the unloading member to 
provide loading thereof on the mandrel for splining. The valving also has 
an unload cycle position where both the load and unload cylinder pistons 
are hydralically driven so as to move the loading and unloading members in 
a direction away from the mandrel to unload a splined thin-wall power 
transmission member. 
In the preferred mode of the hydraulic control circuit, the valving 
includes a load valve that operates the load cylinder and an unload valve 
that operates the unload cylinder. The load valve communicates the 
opposite sides of the load cylinder piston with the supply and return 
conduits in both the load and unload cycle positions but in opposite 
orientations so as to provide oppositely directed hydraulic driving of the 
loading member. In the load cycle position, the unload valve communicates 
the opposite sides of the unload cylinder with the return conduit to 
permit the driving of the unloading member by the hydraulic driving of the 
loading member under the impetus of the load cylinder. In the unload cycle 
position, the unload valve communicates the opposite sides of the unload 
cylinder with the supply and return conduits to provide hydraulic driving 
of the unloading member away from the mandrel. 
Between loading operations, the load and unload cylinders move the loading 
and unloading members away from each other for an index cycle of the load 
table. The load valve has an index cycle position that communicates the 
opposite sides of the load cylinder piston with the return conduit. The 
unload valve has an index cycle position that communicates the opposite 
sides of unload cylinder piston with the supply and return conduits in the 
opposite orientation as in the unload cycle position so as to 
hydraulically drive the unloading member away from the loading member. 
A load table valve of the circuit is associated with the load table and has 
a load-unload position that isolates the load table from both the supply 
and return conduits and an index cycle position for communicating the load 
table with the supply and return conduits to provide indexing of the load 
table. A previously splined thin-wall member is moved out of alignment 
with the loading and unloading members upon the indexing as the next 
thin-wall member to be splined is moved into alignment therewith in 
preparation for loading. 
The objects, features, and advantages of the present invention are readily 
apparent from the following detailed description of the best mode for 
carrying out the invention when taken in connection with the accompanying 
drawings.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to FIG. 1 of the drawings, a hydraulic control circuit generally 
indicated by 10 is constructed in accordance with the present invention 
and operates a schematically indicated loader 12 to provide loading of 
thin-wall power transmission members for a splining operation as well as 
unloading of the splined thin-wall members. Load and unload cylinders 14 
and 16 of loader 12 have associated pistons 18 and 20, respectively, whose 
rods 22 and 24 are connected to loading and unloading members 26 and 28. 
Cooperation of the loading and unloading members 26 and 28 moves thin-wall 
members to be splined from a schematically indicated load table 30 and 
returns the splined members to the load table in preparation for the next 
cycle. 
Referring to FIG. 2, a spline forming machine generally indicated by 32 is 
loaded and unloaded by loader 12 under the control of the hydraulic 
circuit. Upper and lower bases 34 and 36 of the machine 32 are 
interconnected by a vertically extending connecting portion 38 and project 
forwardly therefrom so as to define a workspace 40 where thin-wall spline 
forming is performed. Conventional slideways 42 on the upper and lower 
bases 34 and 36 mount upper and lower toothed dies embodied by upper and 
lower racks 44 with associated forming faces having teeth 46 spaced along 
the lengths thereof between leading and trailing ends of the racks. An 
externally toothed mandrel 48 that is rotatably mounted within the 
workspace 40 about an axis of rotation A receives an annular thin-wall 
power transmission member 50 to be splined by operation of the loader 12. 
A schematically indicated drive mechanism 52, such as of the type 
disclosed by the United States patent of Anderson U.S. Pat. No. 3,793,866, 
moves the toothed racks 44 in the direction of arrows 54 from their 
end-to-end relationship shown into an overlapping relationship in order to 
perform the splining. Such movement of the toothed racks in opposite 
directions to each other on opposite sides of the axis A meshes the die 
and mandrel teeth with an annular thin-wall sleeve of the power 
transmission member 50 therebetween in order to perform the thin-wall 
splining. Drive mechanism 52 subsequently moves the toothed racks 44 in 
the opposite direction as arrows 54 back to the end-to-end position shown 
for unloading of the splined member 50 by the loader 12. 
Referring to FIG. 3, loader 12 moves each power transmission member 50 to 
be splined from the load table 30 to a mounted position on the mandrel 48 
for the splining operation and thereafter moves the splined power 
transmission member back to the load table in preparation for the next 
cycle. Load table 30 is generally of the type disclosed by U.S. Pat. No. 
4,155,237 and includes a schematically illustrated index carriage 56 
having sets of workpiece positioners 58 for locating power transmission 
members received by the carriage. Indexing of carriage 56 moves each set 
of positioners 58 initially into alignment with an unshown input chute to 
receive a power transmission member 50 therefrom, thereafter into 
alignment with the loader 12 along the axis of mandrel rotation for the 
splining operation, and subsequently into alignment with an output chute 
to deliver the splined power transmission member to a suitable storage 
bin. Operation of the loader 12 moves the power transmission member 50 in 
alignment therewith from the load table 30 onto the mandrel 48 such that 
meshing of the die teeth 46 and teeth 60 of the mandrel provides the 
splining of an annular thin-wall sleeve 62 of the power transmission 
member in the manner previously described. An annular end wall 64 of the 
power transmission member is clamped between the loading and unloading 
members 26 and 28 during the movement onto the mandrel for the splining 
and is moved thereby after the splining from the mandrel back to the load 
table in preparation for the next cycle. 
Movement of the loading and unloading members 26 and 28 as shown in FIG. 3 
takes place along the axis A of mandrel rotation. Loading member 26 
includes a shaft 66 connected to the piston rod of the hydraulic load 
cylinder and also includes a rotatable clamp 68 which has an annular 
clamping surface 70 that clamps the end wall 64 of the thin-wall member 50 
against an end 72 of the mandrel 48 during the splining operation. 
Unloading member 28 includes a shaft 74 connected to the piston rod of the 
unload cylinder and also has an enlarged head 76 mounted on the end of the 
shaft 74. An annular clamping surface 78 of the unloading member head 76 
cooperates with the clamping surface 70 on the loading member clamp 68 to 
engage the end wall 64 of the thin-wall member 50 to provide both loading 
and unloading. 
Mandrel 48 shown in FIG. 3 is mounted on a spindle 80 for rotation about 
the axis A and is secured thereto by a plurality of bolts 82 (only one 
shown) and by a key 84 that is secured to the spindle and received within 
a radial slot 86 in the mandrel. An annular extension 88 of the spindle 86 
is received within a central opening 90 of the mandrel and supports a 
bushing 92 that permits the unloading member shaft 74 to move axially 
along the mandrel rotational axis A during the loading and unloading 
movements. An enlarged end 94 of the mandrel opening 90 receives the 
enlarged head 76 of the unloading member 28 during the splining operation 
such that the clamping surface 70 of the loading member clamp 68 can clamp 
the end wall 64 of the thin-wall member 50 being splined against the 
mandrel end 72. A locator 96 of a round shape on the loading member clamp 
68 is received within a round opening 98 in the end wall 64 of the 
thin-wall member 50 so as to provide accurate location thereof during the 
loading operation onto the mandrel and is also received within a round 
depression 100 in the enlarged head 76 of the unloading member 28 to 
permit the clamping of the end wall by the clamping surfaces 70 and 78. 
With reference to FIG. 1, the hydraulic control circuit 10 for operating 
the loader 12 includes a high pressure supply conduit 102 for feeding 
pressurized hydraulic fluid to the load and unload cylinders 14 and 16. A 
hydraulic pump 104 has an inlet 106 connected to a conduit 108 that is fed 
from a tank 110 of hydraulic fluid and has an outlet 111 that is connected 
to conduit 102. Control circuit 10 also includes a low pressure return 
conduit 112 that receives hydraulic fluid from the cylinders 14 and 16 for 
flow back to the tank 110. A spring biased check valve 114 of the return 
conduit 112 maintains a predetermined low pressure in the return conduit. 
Valving 116 of the circuit communicates the opposite sides of the load and 
unload cylinder pistons 18 and 20 with the supply and return conduits 102 
and 112 to operate the loader 12. As is more fully hereinafter described, 
the valving 116 has a load cycle position where the load cylinder piston 
18 has its right side communicated with the supply conduit 102 and its 
left side communicated with the return conduit 112 so as to be 
hydraulically driven toward the left which corresponds to a direction from 
the load table 30 toward the mandrel on which the splining is performed as 
previously discussed. Such movement of the loading member 26 toward the 
left provides the impetus for driving the unloading member 28 toward the 
left with a thin-wall member to be splined clamped between the rotatable 
clamp of the loading member and the unloading member, as previously 
described, in order to provide loading thereof for the spline forming 
operation. Valving 116 of the control circuit also has an unload cycle 
position where the left sides of both the load and unload cylinder pistons 
18 and 20 are communicated with the supply conduit 102 and their right 
sides are communicated with the return conduit 112 so as to be 
hydraulically driven toward the right in order to drive both the loading 
and unloading members 26 and 28 in a direction away from the mandrel to 
unload a splined thin-wall power transmission member for movement back to 
the load table 30. 
With continuing reference to FIG. 1, the valving 116 of the control circuit 
preferably includes a load valve 118 that operates the load cylinder 14 
and an unload valve 120 that operates the unload cylinder 16. Branches 122 
and 124 of the high pressure supply conduit 102 respectively communicate 
the load and unload valves 118 and 120 to the outlet of the pump 104. 
Branches 126 and 128 of the return conduit 112 respectively communicate 
the load and unload valves 118 and 120 with the tank 110 through the check 
valve 114 for return of hydraulic fluid. Conduits 130,132 and 134, 136 
respectively communicate the load and unload valves 118 and 120 with the 
oppositely facing right and left sides of the load and unload cylinder 
pistons 18 and 20. Both the load and unload valves 118 and 120 include 
valve elements that are each biased by an associated pair of biasing 
springs 140 to a center position. Solenoids 142,144 and 146,148 
respectively associated with the load and unload valves 118 and 120 are 
connected by electrical conduits 143,145 and 147,149 to an electrical 
control circuit 150 to actuate valve element movement against the bias of 
springs 140. 
In the load cycle position, the load valve 118 has its solenoid 142 
actuated so as to move the valve element thereof toward the left such that 
pressurized hydraulic fluid is fed from the high pressure conduit 102 
through its branch 122 and through valve 118 to conduit 130 for flow to 
the right side of the load cylinder piston 18. The left side of the load 
cylinder piston 18 is then communicated by conduit 132 through the load 
valve 118 to the branch 126 of the return conduit 112 in order to permit 
fluid to be returned to the tank 110 as the loading member 26 is 
hydraulically driven toward the mandrel to load a thin-wall member to be 
splined. Load valve 118 also has an unload cycle position where the 
solenoid 144 is actuated to move the valve element thereof toward the 
right so as to communicate the branch 122 of the high pressure conduit 102 
with conduit 132 in order to supply pressurized hydraulic fluid to the 
left side of the load cylinder piston 18 and thereby hydraulically drive 
the loading member 26 toward the right. Conduit 130 which is communicated 
with the right side of the load cylinder piston 18 is then also 
communicated through the load valve 118 with the branch 126 of the return 
conduit 112 to permit the return of hydraulic fluid to the tank 110 as the 
loading member 28 is driven away from the mandrel. Also, load valve 118 
has an index cycle position where the valve element thereof is positioned 
at the central location shown such that both sides of the load cylinder 
piston 18 are communicated with the return conduit 112. The differential 
area of the load cylinder piston 18 as a result of the connection of the 
rod 22 to its right side and the slight pressure in the return conduit 112 
provides a bias of this piston toward the right such that the loading 
member 26 is biased toward the right during the index cycle. 
Unload valve 120 has a load cycle position where both solenoids 146 and 148 
are unactuated such that the valve element thereof is in the center 
location shown such that the branch 128 of the return conduit 112 is 
communicated through the unload valve by conduits 134 and 136 with the 
opposite sides of the unload cylinder piston 20. Since the unload cylinder 
piston 20 has a differential area on its opposite sides as a result of the 
connection of the rod 24, there is a slight bias of this piston toward the 
right in the load cycle position due to the pressure of the return conduit 
fluid. However, the driving force of the load cylinder applied through the 
loading member 26 overcomes the slight force on the unloading member 28 
and thereby moves the unloading member toward the mandrel with the 
thin-wall member clamped therebetween in the manner previously described. 
Unload valve 120 has an unload cycle position where the solenoid 148 is 
actuated to move the valve element thereof toward the right to communicate 
the branch 124 of the high pressure conduit 102 with the conduit 136 in 
order to feed pressurized hydraulic fluid to the left side of the unload 
cylinder piston 20. The unload valve 120 then also communicates the 
conduit 134 communicated with the right side of the piston 20 with the 
branch 128 of the return conduit 112 such that the unloading member 28 can 
be driven away from the mandrel to unload a previously splined thin-wall 
member. Also, unload valve 120 has an index cycle position where solenoid 
146 is actuated to move the valve element thereof toward the left in order 
to communicate the branch 124 of the high pressure conduit 102 with the 
conduit 134 so as to feed pressurized hydraulic fluid to the right side of 
the unload cylinder piston 20. The unload valve 120 then communicates the 
conduit 136 that is communicated with the left side of piston 20 with the 
branch 128 of the return conduit 112 for return of fluid such that the 
unloading member 28 is driven away from the loading member 26 and 
maintained out of contact with the load table 30 for an index cycle. 
Limit switches 151 and 152 as well as a tripper 154 on the piston rod 22 of 
the load cylinder 14 and limit switches 156 and 158 as well as a tripper 
160 on the piston rod of the unload cylinder 16 cooperate to control 
operation of the valves 118 and 120 through the electrical control circuit 
150. 
Hydraulic control circuit 10 also includes a load table valve 162 whose 
valve element is biased by a spring 164 to a load-unload position, as 
shown, where a branch 166 of the high pressure supply conduit 102 and a 
branch 168 of the load pressure return conduit 112 are both isolated from 
conduits 170 and 172 that are communicated with a hydraulic actuator of 
the load table 30. A solenoid 174 of the load table valve 162 is connected 
by an electrical conduit 175 with the electrical control circuit 150 and 
is actuated to move the valve element of this valve toward the right 
against the bias of the spring 164 in order to feed pressurized hydraulic 
fluid from the high pressure branch 166 to the conduit 170 and thus to the 
load table actuator for indexing movement. Return hydraulic fluid is then 
fed by the conduit 172 through the valve 162 to the branch 168 of the 
return conduit 112 for flow back to the tank 110. A limit switch 178 is 
actuated by a suitable tripper of the load table after completion of the 
indexing cycle. 
CYCLE OPERATION 
A complete description of the load cycle operation will be described to 
facilitate an understanding of the operation of the hydraulic control 
circuit 10 shown in FIG. 1. Both the load and unload valves 118 and 120 
are in the index cycle position prior to indexing with the loading and 
unloading members 26 and 30 positioned on opposite sides of the load table 
30 such that indexing can be performed. Thus, both solenoids 142 and 144 
of the load valve 118 are unactuated so that the load cylinder piston 18 
is biased toward the right by the fluid pressure of the return conduit 112 
acting on the differential piston area, and the unload valve 120 has its 
solenoid 146 actuated so that high pressure fluid from conduit 102 is 
supplied to the right side of the unload cylinder piston 20 to provide 
driving and positioning thereof toward the mandrel away from the load 
table. After each indexing cycle of the load table 30, tripping of the 
switch 178 actuates the electrical control circuit 150 so as to commence a 
loading operation. Loading is commenced by initially actuating the 
solenoid 148 of the unload valve 120 to drive the unloading member 28 in 
the unloading direction and into engagement with the next thin-wall member 
to be splined at the load table 30 whereupon limit switch 156 is tripped 
to deactuate the solenoid 148 and thus center the load valve 120 and to 
also actuate the solenoid 142 of the load valve 118 for positioning in its 
load cycle position such that high pressure fluid is supplied to the right 
side of the load cylinder piston 18 to drive the loading member 26 toward 
the load table 30. Upon engaging the next thin-wall member to be splined, 
the driving of the loading member 26 clamps the thin-wall member in 
cooperation with the unloading member 28 and moves the unloading member 
against the bias of the low pressure return fluid acting on the 
differential area of the piston 20 such that the thin-wall member is 
loaded on the mandrel for the spline forming operation. Upon reaching the 
mandrel, switch 152 of the load cylinder piston 152 is tripped to indicate 
that splining can begin while maintaining the supply of high pressure 
fluid to the right side of the load cylinder piston 18 such that the 
rotatable clamp of the loading member 26 clamps the thin-wall member 
against the mandrel as previously discussed. 
After the splining operation is completed, a suitable switch of the machine 
operated the electrical control circuit 150 to actuate solenoids 144 and 
148 of the load and unload valves 118 and 120 to provide positioning 
thereof in their unload cycle positions and consequent hydraulic driving 
of both the loading and unloading members away from the mandrel back to 
the load table. Upon reaching the load table, the loading member 26 
continues to be hydraulically driven away from the mandrel until tripper 
154 trips switch 151 whereupon the load valve 118 is moved to its index 
cycle position with the loading member 26 biased to the right by the 
return fluid pressure acting on the differential area of the load cylinder 
piston 18. Upon unloading member 28 reaching the load table 30, the 
tripper 160 trips switch 156 to deactuate the solenoid 148 and actuate the 
solenoid 146 of the unload valve 120 such that the unload cylinder piston 
20 is driven back toward the left away from the load table and then trips 
the switch 158. With both switches 151 and 158 tripped, the electrical 
control circuit 150 actuates the solenoid 174 to index the load table 30 
whereupon tripping of the switch 178 upon completion of the indexing 
commences the next cycle. 
For a complete understanding of the construction of the loading and 
unloading member 26 and 28, reference should be made to my copending 
application Ser. No. P-322 which is being filed concurrently herewith and 
assigned to the assignee of the present invention. 
While the best mode for practicing the invention has been described in 
detail, those familiar with the art to which this invention relates will 
recognize various alternative designs and embodiments for practicing the 
invention as defined by the following claims.