SKID MOUNTED PRECISION HEAT TREAT SYSTEM

Abstract: A heat treat system (10) for continuous processing of annular parts (12) includes a heat treat station (14), a quench station (15) and a temper station (16) mounted on a base (50) and connected to a system control (11). A part loader (74) delivers each of the parts (12) to the bottom of a part transfer device (55) which moves the parts in a stack through an induction heating coil (24a, 24b) in the heat treat station (14). A part gripper (81) moves each heat treated part (12) from the heat treat station (14) to a quench die (32) in the quench station (15) for quenching by fluid from a cooling supply (34). The part gripper (81) then moves each quenched part (12) from the quench station (15) to an induction heating coil (40) in the temper station (16) for tempering the parts. The control system (11) includes a computer (17) connected to a memory (18) in which are stored power values for starting up and shutting down the heat treat station (14).

Description: TITLE SKID MOUNTED PRECISION HEAT TREAT SYSTEM This application claims priority from United States Provisional Application Serial Number 60/007,360, entitled "Skid Mounted Precision Heat Treat System", filed November 20, 1995. BACKGROUND OF THE INVENTION The present invention relates generally to a method and apparatus for heat treating metal parts and, in particular, to a method and apparatus for processing precision cylindrical parts in a continuous flow through heat treat, quench and temper. The heat treating of cylindrical parts, such as bearing races, involves the steps of heating the parts to an austentizing temperature and soaking at that temperature, quenching the parts and tempering the parts. Typically, these processing steps are performed at separate stations and involve the transfer of the parts among several fixtures. Problems associated with this prior art method are lost time during the transfers from station to station and lost time during the change of fixtures when different size parts are being processed. One proposed solution to such problems is a system that utilizes a stack coil for heating and a tube sizing mechanism after quench to minimize distortion. However, this system does not have control of the time versus temperature curve in the stack, requires changeover of the tube sizing mechanism when different O.D. parts are to be processed and does not provide a temper station. Other prior art systems include heat treat and press quench systems mounted on a common base. SUMMARY OF THE INVENTION The present invention concerns a heat treat system for the continuous processing of annular parts. The system includes a base, a heat treat station mounted on the base for heating a stack of annular parts, a quench station mounted on the base for cooling the parts, a gripper means movably mounted on the base for moving the parts from the heat treat station to the quench station, and a system control means connected to the heat treat station for controlling heating of the parts, connected to the gripper means for controlling moving the gripper means and connected to the quench station for controlling cooling of the parts. The system also includes a temper station mounted on the base for tempering the parts, wherein the gripper means moves the parts from the quench station to the temper station and wherein the control system is connected to the temper station for controlling tempering of the parts. The method according to the present invention concerns heat treating annular parts in a continuous process comprising the steps of: providing the heat treat station for heating a stack of the parts with the induction heating coil; delivering each of the parts to one end of the stack in the heat treat station; moving the parts through the heat treat station in the stack of parts while heating the parts; providing the quench station for cooling the parts in the quench die; providing the gripper means and moving each of the parts from an opposite end of the stack in the heat treat station to the quench die; supplying cooling fluid from the cooling supply and cooling each of the parts in the quench die; and providing the system control means connected to the heat treat station, the quench station and the gripper means for controlling heating of the parts in and moving the parts through the heat treat station, moving the parts from the heat treat station to the quench station and cooling the parts in the quench station. The method further includes the steps of: providing the temper station for heating the parts with the induction heating temper coil; and moving each of the parts with the gripper means from the quench station to the temper station under control of the system control. It is an object of the present invention to reduce distortion in heat treated parts. It is another object of the present invention to process bearing races in a cellular manufacturing manner. It is further object of the present invention to reduce bearing race manufacturing costs by eliminating grinding operations required to correct distorted parts. It is a another object of the present invention to provide part-by-part control over the heat treatment of parts in a continuous manufacturing process. It is a further object of the present invention to provide increased control over the heating, quenching and tempering of parts. It is a another object of the present invention to reduce the number of rejected parts during start up and shut down of a continuous heat treating process. BRIEF DESCRIPTION OF THE DRAWINGS The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: Fig. 1 is a schematic block diagram of a heat treat system in accordance with the present invention; Fig. 2 is a schematic block diagram of the control shown in the Fig. 1; Fig. 3 is a schematic block diagram of a heat treating means in the heat treat station shown in the Fig. 1 ; Fig. 4 is a schematic block diagram of a quenching means in the quench station shown in the Fig. 1; Fig. 5 is a schematic block diagram of a tempering means in the temper station shown in the Fig. 1 ; Fig. 6 is a top plan view of the heat treat system shown in the Fig. 1; Fig. 7 is a top plan view of a part transfer means shown in the Fig. 6; Fig. 8 is a cross-sectional side elevation view of the part transfer means taken along the line 8-8 in the Fig. 7; Fig. 9 is a top plan view of a part loading means shown in the Fig. 8; Fig. 10 is a table of the power applied to the heating coil during loading of the part transfer means; Fig. 11 is a table of the power applied to the heating coil during unloading of the part transfer means; Fig. 12 is an elevation view of a part gripper means for moving parts from the heat treat station to the quench station; Fig. 13 is a schematic view of a gripper positioning means for the part gripper means shown in the Fig. 12; and Fig. 14 is a part cross-sectional, part schematic view of the quench station shown in the Fig. 1. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention concerns an integrated heat treat system for processing parts utilizing induction heating to produce results comparable to furnace heat treating and improved part distortion. The system precisely controls the induction heating start up and shut down. There is shown in the Fig. 1 a schematic block diagram of a system 10 for heat treating parts in accordance with the present invention. The system 10 includes three processing stations and a system control 11. A part 12 to be treated travels along a processing path 13 and enters a first processing station 14 which is a precision heat treat station connected to the system control 11. As described below, the part 12 is heated to the austentizing temperature under the control of the system control 11. Once heated, the part 12 leaves the first processing station 14 and travels along the processing path 13 to enter a second processing station 15 which is a quench station connected to the system control 11. Once quenched, the part 12 leaves the second processing station 15 and travels along the processing path 13 to enter a third processing station 16 which is a temper station connected to the system control 11. Once tempered, the part 12 leaves the third processing station 16 and the system 10 on the processing path 13. In the integrated system 10 designed in accordance with this invention, it is possible to heat the part 12 to austentizing temperature and soak at a chosen temperature, then quench and temper, all in one machine base. Furthermore, the parts 12 are delivered to the first station 14 at a rate (cycle time) whereby a plurality of the parts are moved as a stack through the first station and the top heat treated part in the stack is moved to the quench station during each cycle. As discussed below, the system accommodates parts in a range of thicknesses and a range of diameters. The system control 11 is shown in more detail in the schematic block diagram of the Fig. 2. A computer means 17 in the form of a central processing unit (CPU) has a first input/output connected to an input/output of a memory means 18. The memory means 18 stores operating system and application software instructions which are executed by the CPU 17. Also connected to the CPU 17 is an input device means 19 such as a keyboard and/or a mouse for inputting data and commands. A display means 20 is connected to the CPU 17 for displaying the data and commands entered through the input device means 19, information generated by the operating system and application software and information generated by the processing stations 14, 15 and 16. A second input/output of the CPU 17 is connected to an input\output of an interface means 21 which converts between control system signals recognized by the CPU 17 and processing station signals recognized by the devices in the three stations of the system 10. A line 22 represents a plurality of data paths between the control system 11 and the stations 14, 15 and 16 which paths can be any known standard communication means. One embodiment of a heat treating means 23 in the heat treat station 14 is shown in schematic block diagram form in the Fig. 3. The heat treating means 23 includes a first induction heating coil 24a located at the entrance of the part 12 to the station. The path 13 of the part 12 through the station 14 passes through the first coil 24a and then through a second induction heating coil 24b before exiting the first station. The first coil 24a is a multiturn induction coil which provides rapid heat up to austentizing temperatures. The first coil 24a is provided with electrical power from a first power supply 25 which is connected to the coil through a first controller 25. A first sensor 27 is connected to the controller 26 for generating a first sensed condition signal representing the actual value of a parameter related to the coil 24a. The controller 26 responds to a difference between a value of a first setpoint signal representing a desired value of the parameter related to the coil 24a and a value of the first sensed condition signal to control the electrical power supplied to the coil from the power supply 25 to maintain the coil in a steady state heating mode at the desired rapid heat up temperature. The second coil 24b is a multiturn induction coil which provides soak time at a desired temperature to dissolve carbides and for grain refinement. The second coil 24b is provided with electrical power from a second power supply 28 which is connected to the second coil through a second controller 29. A second sensor 30 is connected to the second controller 29 for generating a second sensed condition signal representing the actual value of a parameter related to the coil 24b. The second controller 29 responds to a difference between a value of a second setpoint signal representing the desired value of the parameter related to the second coil 24b and a value of the second sensed condition signal to control the electrical power supplied to the coil from the second power supply 28 to maintain the coil in a steady state soak heating mode at the second desired temperature. The first coil 24a is preferably of a shorter length than the second coil 24b. For example, the first coil to second coil ratio may be a 1 :3 ratio in a preferred embodiment. The power supplies 25 and 28, the controllers 26 and 29 and the sensors 27 and 30 can be commercially available devices which are typically utilized to control induction heating processes. The first and second setpoint signals can be inputted utilizing controls provided on the controllers 26 and 29 respectively, or can be provided to the controllers by the CPU 17 over the lines 22 connected to the controllers. The coil parameter being sensed typically is temperature wherein the sensors 27 and 30 are temperature sensors and the sensed condition signals represent an actual value of temperature sensed at or near the coils 24a and 24b. However, other parameters, such as current flow, can be used to control the temperature of the coils wherein the sensors 27 and 30 are electrical current sensors and the sensed condition signals represent an actual value of electrical current flowing through the coils 24a and 24b. Although two coils 24a and 24b are shown in the Fig. 3, more coils or a single coil can be utilized. Each additional coil would be associated with another power supply, another controller and another sensor. However, if the coils 24a and 24b are formed as two sets of consecutive turns of a single coil, only the power supply 25, the controller 26 and the sensor 27 are required. The coil turns representing the first coil 24a can be spaced closer together than the coil turns representing the second coil 24b to provide for the rapid heat up to austentizing temperatures over a shorter travel through the first set of turns and soak time at a desired temperature to dissolve carbides and for grain refinement over a longer travel through the second set of turns during movement of the parts 12 along the processing path 13. Thus, the heat treating means 23, either in the form of multiple multiturn induction coils or a single variable turn density induction coil, provides rapid heat up to austentizing temperatures and soak time at a desired temperature to dissolve carbides and for grain refinement of parts being heat treated in the first processing station 14. The heat treating means 23 is especially useful for achieving full transformation of the microstructure of a part, such as a bearing. This is necessary when induction heat treating high alloy or high carbon steels. There is shown in the Fig. 4, in schematic block diagram form, a quenching means 31 which yields low distortion of the parts 12 during the quench below transformation temperatures. The part 12 enters the second or quenching station 15 along the processing path 13 which leads to a quench die 32. The quench die 32 is coupled to a die actuator 33 which opens the die to receive the part 12, closes the die to retain the part for the quenching step and opens the die again to allow removal of the part. The actuator 33 is connected to the CPU 17 by the lines 22 to receive control signals and send condition signals representing the operative position of the die actuator 33 and the quench die 32. The quench die 32 is provided with a cooling fluid from a cooling supply 34 connected through a valve 35 by a supply line 36. The cooling fluid is returned through a return line 37 connected between the quench die 32 and the cooling supply 34. The valve 35 is coupled to a valve actuator 38 which opens the valve to cool the part 12 in the quench die 32 and closes the valve to stop the cooling. The actuator 38 also is connected to the CPU 17 by the lines 22 to receive control signals and send condition signals representing the operative position of the valve actuator 38 and the valve 35. There is shown in the Fig. 5, in block schematic diagram form, a tempering means 39 of the temper station 16. The tempering means 39 includes an induction heating temper coil 40 located at the entrance of the part 12 to the station 16. The process path 13 of the part 12 through the station 14 passes through the coil 40 before exiting the third station 16. The coil 40 is a multiturn induction coil which provides rapid heat at a tempering temperature. The coil 40 is provided with electrical power from a power supply 41 which is connected to the coil through a controller 42. A sensor 43 is connected to the controller 42 for generating a sensed condition signal representing the actual value of a parameter related to the coil 40. The controller 42 responds to a difference between a value of a setpoint signal representing a desired value of the parameter related to the coil 40 and a value of the sensed condition signal to control the electrical power supplied to the coil from the power supply 41 to maintain the coil in a steady state heating mode at the desired tempering temperature. The setpoint signal can be inputted utilizing controls provided on the controllers 42, or can be provided to the controller by the CPU 17 over the lines 22 connected to the controller. Fig. 6 is a top plan view of the heat treat system 10 shown in the Fig. 1 wherein the system control 11, the heat treat station 14, the quench station 15 and the temper station 16 are mounted on an upper surface of a table-like base 50. A control panel 51 is mounted on the base 50 by a first articulated arm 52 to provide an operator with the input device 19 and the display 20 for controlling the system processes. A diagnostic panel 53 is mounted on the base 50 by a second articulated arm 54 to provide an operator with another one of the input device 19 and the display 20 for detecting and analyzing problems with the operation of the equipment incorporated in the system 10. Adjacent the heat treat station 14 are the power supply 25 and the cooling supply 34 also mounted on the upper surface of the base 50. As stated above, the system 10 is a fully integrated, precision heat treat system that processes parts, such as bearings, in a continuous flow fashion. Prior to this invention, the complete heat treat process including temper has not been available on a common machine base. The portion of the heat treat station 14 which loads the parts 12 into the induction coil, moves the parts through the coil and unloads the parts from the coil is shown in more detail in the Figs. 7 through 9. An heat treat part transfer means 55, mounted on the base 50 as shown in the Fig. 6, is shown in top plan view in the Fig. 7. The part transfer means 55 is shown in a cross- sectional side elevation view in the Fig. 8. The part transfer means 55 is generally cylindrical and surrounds the induction heating coil (only the portion 24b can be seen). A generally cylindrical hollow housing 56 has upper and lower groups of three guide rod supports 57 extending through a wall thereof. The supports 57 in each group are generally equally spaced circumferentially and each support in one group is generally vertically aligned with a coπesponding support in the other group. Thus, each vertically aligned pair of the supports 57 has inner ends interior of the housing 56 which ends retain an associated generally vertically extending guide rod 58. Outer ends of the guide rod supports 57, exterior of the housing 56, are slidably supported in ceramic bearings 59 mounted on the exterior of the housing. Thus, the guide rod supports 57 and the guide rods 58 are radially movable relative to a longitudinal axis 60 of the coil 24b to accommodate different diameter parts 12 (a large part 12a and a small part 12b are shown in phantom in the Fig. 7). The guide rods 58 contact the outer diameter of stacked cylindrical parts 12 to maintain the parts concentric with the longitudinal axis 60. The outer ends of each vertically aligned pair of the supports 57 are attached to an associated generally vertically extending cam bar 61. A plurality of upper and lower cam plates 62 each have an arcuate slot 63 of varying radius formed therein for slidably retaining an associated one of the cam bars 61. If the plates 62 are rotated about the longitudinal axis 60 in the direction of an arrow 64, the cam bars 61, the guide rod supports 57 and the guide rods 58 will all move radially inwardly to accommodate the diameter of the small part 12b. Rotation of the plates 62 in the opposite direction will move the guide rods radially outwardly to accommodate the diameter of the large part 12a. As shown in the Fig. 7, the upper cam plates 62 are attached to a periphery of an internal ring gear 65 having an external V-groove raceway formed thereon. The raceway is engaged by a plurality of V-groove roller bearings 66 which are rotatably attached to a lower surface of an upper support ring 67a mounted on an upper end of the housing 56. The internal teeth of the ring gear 65 are engaged by a pinion gear 68 mounted on a generally vertically extending drive shaft 69. In a similar manner, the lower cam plates 62 are attached to a periphery of another internal ring gear 65 having an external V-groove raceway formed thereon. The raceway is engaged by a plurality of V-groove roller bearings 66 which are rotatably attached to an upper surface of a lower support ring 67b mounted on a lower end of the housing 56. The internal teeth of the ring gear 65 are engaged by another pinion gear 68 mounted on the drive shaft 69. A lower end of the drive shaft 69 is attached to an upper end of a coupler 70 which has a lower end attached to an output shaft of a gear reducer 71. The gear reducer 71 is mounted on a lower surface of the base 50 and the output shaft extends upwardly through an aperture. A servo motor 72 is attached to an input of the gear reducer 71 for rotating the drive shaft 69 thereby rotating the cam plates 62 about the axis 60 to radially move the guide rods 58. The servo motor 72 is connected to the lines 22 for receiving control signals representing the degree of desired rotation. A lower end of one of the cam bars 61 is connected to a linear position sensor 73 which generates a position signal on one of the lines 22 connected between the system control 11 and the sensor. The parts 12 are moved into the heat treat part transfer means 55 by a part loading means 74 mounted on the base 50 as shown in the Fig. 8 and the Fig. 9. The part loading means 74 includes a pair of positive stops 75 each slidably movable in a radial direction in a coπesponding one of a pair of guide bushings 76 mounted on the base 50. The outer ends of the stops 75 are attached to the lower ends of coπesponding ones of the cam bars 61. The inner ends of the stops 75 remain vertically aligned with coπesponding ones of the guide rods 58 as the part transfer means is adjusted to accommodate different diameter parts 12a and 12b. The parts are individually loaded at a loading position 77 adjacent a spring loaded part mover 78. The part mover 78 is slidably mounted on a guide rail 79 attached to the base 50. The part mover 78 moves the parts 12 from the loading position 77 to a position above a vertically movable stack support 80 which is in a retracted position below the upper surface of the table 50. The part mover 78 and the stops 75 position the part 12 concentric with the longitudinal axis 60. The stack support 80 is then actuated to lift the part 12 into contact with the bottom part in the stack of parts being retained by a stack gripper assembly 58a which is actuated to engage the periphery of the bottom part in the stack. Once contact is made, the stack gripper assembly 58a is retracted to permit the parts in the stack to rest on the stack support 80 which then raises the entire stack of parts to an unload position where the top part is removed from the stack as described below. The stack support 80 is lowered to align the bottom part with the stack gripper assembly 58a which is extended to engage the newly added part at the bottom of the stack, and the stack support 80 is retracted to receive the next part. As stated above, a multiturn induction coil 24a and 24b provides rapid heat up to austentizing temperatures and soak time at a desired temperature to dissolve carbides and for grain refinement. The multizone coil is provided to ensure adequate soak time at a desired temperature to dissolve carbides and to achieve full transformation of the microstructure of a part, such as a bearing. This is necessary when induction heat treating high alloy or high carbon steels. A multiturn stack induction heating coil provides the advantages of having a continuous flow production. A control algorithm is preferably used in the system control 11 to interface with the part loading means 74 within the system that loads and unloads the parts 12 into the stack, the main machine control, and the temperature control for the coil. The system main control 11 can activate the control algorithm at start up, shut down or when product flow is disrupted. Upon activation, the algorithm directs the servolift through a start up or shut down sequence, whichever is appropriate, to index parts into or out of the stack. The temperature or power control is biased by the dynamic status of part count and part positions in the stack. The control algorithm will vary the control parameters, such as timing, sequences, number of parts, etc. based upon the system parameters known from a particular operation. There is shown in the Fig. 10 a load table coπelating the number of the parts 12 in the part transfer means 55 to the electrical power provided to the induction heating coil 24a and 24b. For example, the heating coil can be sized such that thirty-one parts of a predetermined thickness represent a full stack. At start up, no power is applied to the heating coil as the first eight parts are loaded by the part loading means 74. The numbers in the power column beginning with the ninth part represent the kilowatts of electrical power applied to the coil during the heating interval which occurs when the stack support is retracted below the upper surface of the table 50 and occupies a fixed portion of the total time required to cycle one part. The power value is increased in predetermined steps as the parts are loaded. After thirty-one parts have been placed in the stack, the top of the stack has reached the top of the coil and the system control maintains constant electrical power to the coil during the continuous process. The table shown in the Fig. 10 has room for forty start up power values to accommodate processing of thinner parts wherein more than thirty-one parts represent a full stack. Obviously, the table can be expanded or contracted depending upon the number of parts in a full stack of the thinnest parts to be processed. The load table can be stored in the memory 18 shown in the Fig. 2. If an incoming part is not detected in a predetermined time period, the system control 11 shuts down the system 10 utilizing a purge table shown in the Fig. 11 while the part transfer means 55 is emptied of the parts in the stack. The fully loaded part transfer means 55 contains thirty-one parts of which eight have not yet entered the coil. During the unloading of the first seven parts, the power is maintained at the maximum value. When the eighth part is unloaded, the bottom of the stack enters the coil and the power is reduced in predetermined steps as the parts are unloaded. During a purge sequence, the stack support 80 does not have to be retracted and can continue to support the stack of parts under control of the system control 11. At the part number thirty-two, no parts remain in the stack and the power is shut off. Similar to the load table shown in the Fig. 10, the shut down purge table has room for forty power values and can be stored in the memory 18 shown in the Fig. 2. As shown in the Fig. 12 and the Fig. 13, a gripper means 81 is utilized to remove the part at the top of the stack from the part transfer means 55 to the quench station 15. In the Fig. 12, a stack of the parts includes a top part 12c and a next lower part 12d. During heating, the parts 12c and 12d can become stuck together making it difficult to lift the part 12c from the top of the stack. An inner gripper finger 82 is moved into contact with an outer surface of the part 12d while an outer gripper finger 83 is moved into contact with an inner surface of the part 12c. The finger 82 has a radial protrusion 84 formed at a lower end thereof for contacting the part 12c and offsetting the body of the inner finger from the outer surface of the part 12c by a shear distance 85. As the inner finger 82 and the outer finger 83 are moved toward one another toward a centerline 86 offset from the longitudinal axis 60 by the shear distance 85, the parts 12c and 12d are caused to separate. There is shown in the Fig. 13 a gripper positioning means 87 having a frame 88 slidably supported on a linear bearing assembly 89 and supporting the gripper means 81. A gear rack 90 is attached to the frame 88 and engages a pinion drive 91 which receives control signals from the system control 11 over the line 22. The drive 91 is controlled for moving the frame 88 and the gripper means 81 transverse to the centerline 86 to accommodate parts of different diameters. A position sensor 92 is coupled to the gear rack 90 for generating a signal representing the position of the gripper means 81 relative to the centerline 86 to the system control 11 on the line 22. Once the part 12c is gripped, the gripper means 81 travels along the frame 88 to the quench station 15. There is shown in the Fig. 14 a part cross-sectional, part schematic view of the quench station 15. The gripper means 81 deposits the part 12 in the interior of the quench die 32. The die 32 has a movable upper die portion 93 attached to a ram 94 for movement toward and away from a stationary lower die portion 95. The ram 94 is attached to them actuator 33 shown in the Fig. 4. Thus, the ram 94 and the upper die portion 93 are raised under control of the system control 11, the part 12 is deposited on the lower die portion 95 and the upper die portion is lowered to close the die. The lower die portion 95 has a tapered portion 96 which faces a tapered portion 97 of the upper die portion 93 to accommodate parts of different internal diameters. The lower die portion 95 has a cooling passage 98 formed therein which extends from a lower surface upwardly through the center of the tapered portion 96. The upper die portion 93 has a cooling passage 99 formed therein which extends from the center of the tapered portion 97 upwardly to an upper surface of the die 32. The passage 98 is in fluid communication with the valve 35 through the supply line 36 to receive cooling fluid from the supply 34 shown in the Fig. 4. The passage 99 is in fluid communication with the return line 37. The open areas between the blades 97a permit the cooling fluid to flow around the outside of the part 12 and exit the side of the quench die 32. The fixture quench station 15 yields low distortion during the quench below transformation temperatures. The quench press station die 32 maintains the part 12 in a round and flat state while it is being quenched. The part 12 remains in the quench die 32 until a temperature of 120°F is reached. This provides for minimum distortion. A cold quench is preferably used to cool the workpiece from 400°F down to 120°F in order to minimize the quench cycle. It is important that quench rates down to approximately 400° are maintained relatively slow to ensure that no micro-cracking of the workpiece occurs. A cold circuit of quench media is switched, preferably by solenoid valves, into the quench die during the portion of the cycle where the part 12 is cooled from 400°F to 120°F. As shown in the Fig. 13, the gripper positioning means 87 can be provided with a second gripper means 100 attached to the opposite end of the frame 88 from the first gripper means 81. When the first gripper means 81 is positioned at the heat treat station 14 to pick up a finished part from the top of the stack, the second gripper means 100 is positioned at the quench station 15 to pick up a finished part. When the first gripper means 81 is positioned at the quench station 15 to deposit a part, the second gripper means 100 is positioned at the temper station 16 to deposit a part. The final temper station 16 completes the heat treat process with stress relief, final required hardness, and final required retained austenite levels. The temper station 16 is not shown in detail since it is similar in construction to the heat treat station 14. Significant advantages are provided by the heat treating system 10 designed in accordance with this invention because there is specific control of the temperature of parts (such as bearings) in a stack, specific control of a time versus temperature curve in a stack, and the machine is not limited to one outer diameter size part. A further enhancement to the system 10 is a gas cover 101 (Fig. 6) at the point of induction heating. A sealed induction heating stack coil with a gas cover prevents the oxidation of parts being processed. Because the cycle times common in an induction heat process are relatively short, and the load and unload sequences happen so frequently, the amount of oxygen introduced into the stack must be minimized during the load and unload sequences. It is important to keep the oxygen content in the stack below a level that leads to surface scaling. Accordingly, the system includes purge chambers (not shown) on the entrance and exit of the stack in order to control the amount of oxygen within the stack during processing. The sealed chamber cover ensures that the level of oxygen within the stack is maintained at an appropriate level. In summary , the heat treat system 10 for the continuous processing of the annular parts 12 comprises: the base 50; the heat treat station 14 mounted on the base for heating a stack of annular parts; the quench station 15 mounted on the base for cooling the parts; the gripper means 81 movably mounted on the base for moving the parts from the heat treat station to the quench station; and the system control means 11 connected to the heat treat station for controlling heating of the parts, connected to the gripper means for controlling moving the gripper means and connected to the quench station for controlling cooling of the parts. The system 10 also includes the temper station 16 mounted the base 50 for tempering the parts 12, wherein the gripper means 81 moves the parts from the quench station 15 to the temper station and wherein the control system 11 is connected to the temper station for controlling tempering of the parts. The method of heat treating annular parts 12 in a continuous process comprising the steps of: a. providing the heat treat station 14 for heating a stack of the parts with the induction heating coil 24a, 24b; b. delivering each of the parts to one end of the stack in the heat treat station; c. moving the parts through the heat treat station in the stack of parts while heating the parts; d. providing the quench station for cooling the parts in the quench die 32; e. providing the gripper means 81 and moving each of the parts from an opposite end of the stack in the heat treat station to the quench die; f. supplying cooling fluid from the cooling supply 34 and cooling each of the parts in the quench die; and g. providing the system control means 11 connected to the heat treat station, the quench station and the gripper means for controlling heating of the parts in and moving the parts through the heat treat station, moving the parts from the heat treat station to the quench station and cooling the parts in the quench station. The method further includes the steps of: h. providing the temper station 16 for heating the parts 12 with the induction heating coil 40; and i. moving each of the parts with the gripper means 81 from the quench station 15 to the temper station under control of the system control 11. In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its prefened embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.

Claims: WHAT IS CLAIMED IS: 1. A heat treat system (10) for continuous processing of annular parts (12) comprising: a base (50); a heat treat station (14) mounted on said base (50) for heating a stack of annular parts (12); a part loading means (74) mounted on said base (50) for delivering the parts (12) to said heat treat station; a quench station (15) mounted on said base (50) for cooling the parts (12); a gripper means (81) movably mounted on said base (50) for moving the parts (12) from said heat treat station (14) to said quench station (15); and a system control means (11) connected to said heat treat station (14), said part loading means (74), said quench station (15) and said gripper means (81) for controlling delivery of the parts (12) to said heat treat station, heating of the parts in said heat treat station, moving the parts from said heat treat station to said quench station and cooling the parts in said quench station. 2. The system according to claim 1 wherein said heat treat station (14) includes a multiturn induction heating coil (24a,24b) through which the parts (12) pass and a power supply (25) connected to said heating coil for supplying electrical power, said system control (11) being connected to said power supply for controlling the amount of electrical power applied to said heating coil for he<, the parts. 3. The system according to claim 2 wherein said heating oil (24a, 24b) includes a first set of turns (24a) and a second set of turns (24b), said first set of turns being spaced together closer than a spacing of said second set of turns for rapid heat up of the parts (12) in said first set of turns and soak of the parts in said second set of turns. 4. The system according to claim 1 wherein said heat treat station (14) includes a first multiturn induction heating coil (24a) and a second multiturn induction heating coil (24b) through which the parts (12) pass, a first power supply (25) connected to said first heating coil for supplying electrical power for rapid heat up of the parts in said first coil, a second power supply (28) connected to said second coil for supplying electrical power for soak of the parts in said second coil, and said system control (11) being connected to said power supplies for controlling the amount of electrical power applied to said heating coils for heating the parts. 5. The system according to claim 1 including a part transfer means (55) mounted on said base (50) for moving the parts (12) through said heat treat station (14), said part transfer means including a plurality of radially movable guide rods (58) for contacting the stack of parts and drive means (71,72) coupled to said guide rods and connected to said system control (11) for controlling movement of said guide rods to accommodate different diameter parts. 6. The system according to claim 1 wherein said part loading means (74) includes a vertically movable stack support (80) mounted on said base (50) for lifting each of the parts (12) to a bottom of a stack of the parts in said heat treat station (14). 7. The system according to claim 1 wherein said part loading means (74) includes an horizontally movable part mover (78) mounted on said base (50) for moving each of the parts (12) to a position below a bottom of a stack of the parts in said heat treat station (14). 8. The system according to claim 7 wherein said part loading means (74) includes a pair of positive stops (75) mounted on said base (50) for cooperating with said part mover (78) to position each of the parts (12) below a bottom of a stack of the parts in said heat treat station (14). 9. The system according to claim 1 wherein said gripper means (81) is mounted on a gripper positioning means (87) mounted on said base (50), said gripper positioning means being movable transverse to a longitudinal axis (60) of a stack of the parts (12) in said heat treat station (14) to accommodate different diameter parts, and including drive means (90,91) on said gripper positioning means and connected to said system control (11) for moving said gripper positioning means and said gripper means. 10. The system according to claim 1 wherein said quench station (15) includes a quench die (32) for receiving and retaining the part (12), a cooling supply (34) connected to an interior of said quench die through a valve means (35) and a valve actuator (38) attached to said valve means and wherein said valve actuator is connected to said system control (It) for controlling the flow of cooling fluid through said quench die. 11. The system according to claim 1 including a temper station (16) mounted on said base (50) for tempering the parts (12), wherein said gripper means (81) moves the parts from said quench station (15) to said temper station and wherein said control system (11) is connected to said temper station for controlling tempering of the parts. 12. The system according to claim 11 wherein said temper station (16) includes a multiturn induction heating coil (40) through which the parts (12) pass and a power supply (41) connected to said heating coil for supplying electrical power, said system control (11) being connected to said power supply for controlling the amount of electrical power applied to said heating coil for tempering the parts. 13. The system according to claim 1 wherein said heat treat station (14) includes a multiturn induction heating coil (24a,24b) through which the parts (12) pass in a stack and a power supply (25,28) connected to said heating coil for supplying electrical power, said system control (11) includes a computer means (17) connected to a memory (18) for storing a plurality of start up power values associated with numbers of the parts in the stack, said computer means being connected to said power supply for controlling the amount of electrical power applied to said heating coil for heating the parts, and during start up of the system (10) , said computer means is responsive to the number of the parts in the stack for controlling the amount of electrical power applied to said heating coil in accordance with associated ones of said stored power values. 14. The system according to claim 1 wherein said heat treat station (14) includes a multiturn induction heating coil (24a,24b) through which the parts (12) pass in a stack and a power supply (25,28) connected to said heating coil for supplying electrical power, said system control (11) includes a computer means (17) connected to a memory (18) for storing a plurality of shut down power values associated with numbers of the parts in the stack, said computer means being connected to said power supply for controlling the amount of electrical power applied to said heating coil for heating the parts, and during shut down of the system (10), said computer means is responsive to the number of the parts in the stack for controlling the amount of electrical power applied to said heating coil in accordance with associated ones of said stored power values. 15. A method of heat treating annular parts (12) in a continuous process comprising the steps of: a. providing a heat treat station (14) for heating a stack of annular parts (12) with an induction heating coil (24a, 24b); b. delivering each of the parts (12) to one end of the stack in the heat treat station (14); c. moving the parts (12) through the heat treat station in the stack of parts while heating the parts; d. providing a quench station (15) for cooling the parts (12) in a quench die (32); e. providing a gripper means (81) and moving each of the parts (12) from an opposite end of the stack in the heat treat station (14) to the quench die (32); f. supplying cooling fluid from a cooling supply (34) and cooling each of the parts (12) in the quench die (32); and g. providing a system control means (11) connected to the heat treat station (14), the quench station (15) and the gripper means (81) for controlling heating of the parts in and moving the parts through the heat treat station, moving the parts from the heat treat station to the quench station and cooling the parts in the quench station. 16. The method according to claim 15 including the steps of: h. providing a temper station (16) for heating the parts (12) with an induction heating coil (40); and i. moving each of the parts (12) with the gripper means (81) from the quench station (15) to the temper station (16) under control of the system control (11). 17. The method according to claim 15 wherein the step g. includes storing a plurality of start up power values associated with numbers of the parts (12) in the stack in a memory (18) connected to a computer means (17) and controlling the amount of electrical power applied to the heating coil (24a,24b) in accordance with associated ones of the stored power values during a start up of the heat treat station (14). 18. The method according to claim 15 wherein the step g. includes storing a plurality of shut down power values associated with numbers of the parts (12) in the stack in a memory (18) connected to a computer means (17) and controlling the amount of electrical power applied to the heating coil (24a,24b) in accordance with associated ones of the stored power values during a shut down of the heat treat station (14).

Inventors: BORDEN RANDALL P, COLE JOHN F JR, HOLMES GEORGE W JR, POHL GREGORY L, BORDEN, RANDALL, P., COLE, JOHN, F., JR., HOLMES, GEORGE, W., JR., POHL, GREGORY, L.
Applicants: BORDEN RANDALL P, COLE JOHN F JR, HOLMES GEORGE W JR, POHL GREGORY L, ROBOTRON CORP, BORDEN, RANDALL, P., COLE, JOHN, F., JR., HOLMES, GEORGE, W., JR., POHL, GREGORY, L., ROBOTRON CORPORATION
Application year: 1996
Main classification: C21D
IPC codes: C21D1, C21D9