BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side elevational view of a crankshaft for an 8 cylinder internal combustion engine with the main bearings and orbital pin bearings identified;
FIG. 2 is a schematic side elevational view illustrating one inductor for inductively heating and quench hardening a bearing surface of the crankshaft shown in FIG. 1;
FIG. 3 is a simplified side elevational, schematic view similar to FIG. 2, but illustrating the pulsed counter balancing controller used in practicing the present invention;
FIG. 4 is a motion graph of the vertical position for the counter balance mechanism shown in FIG. 3 at 10 degrees arcuate increments;
FIGS. 5A, 5B, 5C and 5D are enlarged side elevational views similar to the view in FIG. 3 illustrating the relationship of cylindrical pin bearing surfaces with respect to the counter balanced flanges of the crankshaft and the center rotational axis of the crankshaft;
FIG. 6 is a schematic diagram of an installation to practice the invention with the three multi-surface hardening stations together with a motion diagram for transferring the crankshaft to and from the three induction hardening stations;
FIG. 7 is a block diagram and flow chart of a portion of the first station illustrating the quenching procedure used in quench hardening main bearings 1, 3 and 5;
FIG. 8 is a combined block diagram and flow chart similar to FIG. 7 illustrating the quench hardening process used for main bearings 2 and 4 in the first station as shown in FIG. 6;
FIGS. 9-13 are graphs illustrating the volume of quenching liquid at 10 degrees increments for quench hardening main bearings 1, 2, 3, 4 and 5 using the procedure set forth in FIGS. 7 and 8;
FIG. 14 is a combined block diagram and flow chart for the process for hardening one of the orbiting cylindrical pin surfaces illustrating an open loop preferred implementation of the invention and a closed loop implementation of the present invention;
FIGS. 15, 16, 17 and 18 are quench flow graphs illustrating the quenching procedure for the orbiting pins after they have been inductively heated illustrating an aspect of the invention for controlling the metallurgical characteristics of the pin surfaces;
FIG. 19 is a combined block diagram and flow chart of the procedure for determining the distortion effect in hardening a particular group of pin bearings;
FIG. 20 is a combined block diagram and flow chart of a procedure similar to the process disclosed in FIG. 19 for measuring the distortion obtained by hardening the main bearings in station 1 of the installation shown in FIG. 6;
FIG. 21 is a circular plotting chart illustrating the end result or effect of performing a basic feature of the procedures disclosed in FIGS. 19 and 20;
FIG. 22 is a combined block diagram and flow chart of the procedure for sequentially hardening the main bearing surfaces and the two groups of pin bearing surfaces employing stations 1, 2 and 3 as illustrated in FIG. 6;
FIG. 23 is a combined block diagram and flow chart of an alternate implementation of the three stations installation illustrated in FIG. 6;
FIG. 24 is a combined block diagram and flow chart for the aspect of the invention for limiting the total indicator run out of the crankshaft shown in FIG. 1;
FIG. 25 is a combined block diagram and flow chart illustrating the technical characteristics facilitating the procedure set forth in FIG. 24;
FIG. 26 is a circular diagram of the procedure for constructing a heat profile to create a look up or data table for controlling the heating cycle of an individual cylindrical surface;
FIGS. 27-33 are representative profiles for the production run created by using the diagnostic procedure schematically illustrated by the chart in FIG. 26;
FIG. 34 is a typical voltage profile for the power directed to a pin using one of the profiles set forth in FIGS. 27-33;
FIG. 35 is a table with the control signal levels for power, quench and counter balance for the pin bearings at different arcuate increments;
FIG. 36 is a table similar to the table of FIG. 36 for the main bearing surfaces of the crankshaft hardened in accordance with the present invention; and,
FIG. 37 is a schematic block diagram illustrating the use of data tables created by the diagnostic procedure set forth in FIG. 26.
PREFERRED EMBODIMENT
The present invention relates to an apparatus and method for hardening the axially spaced bearing surfaces of a crankshaft for a multi-cylinder internal combustion engine, such as crankshaft A for an eight cylinder engine as shown in FIG. 1. The bearing surface means the cylindrical surface and fillets. When cylindrical surface or bearing surface is used it incorporates the adjacent fillets.
While the following embodiments are illustrated and described in the context of induction hardening the exemplary crankshaft A having 5 main and 4 interspersed pin bearings, the invention finds utility in association with induction hardening of any type of crankshaft having any number of pin and main bearings, wherein the invention is not limited to the illustrated embodiments. Moreover, the invention contemplates hardening of individual bearings or groups of bearings, which can be accomplished using two or more such sets, and the broad aspects of the invention are not limited to the number of groups in the illustrated examples, or the constituent members of the exemplary groups or sets described herein.
In the illustrated examples, the crankshaft bearing surfaces are inductively heated and then quench hardened with the objective of providing a straight, undistorted crankshaft with metallurgical characteristics for the individual cylindrical bearing surfaces constituting a tempered hardness. Representative crankshaft A includes axially spaced, cylindrical bearing surfaces 10, 12, 14, 16 and 18 for concentric main bearings M1, M2, M3, M4 and M5 and coaxial with axis x of the crankshaft. In accordance with standard design, shaft A includes cylindrical bearing surfaces 20, 22, 24 and 26 for pin bearings P1, P2, P3 and P4, respectively. The pin bearing surfaces orbit about axis x as shaft A is rotated during induction heating, quench hardening and automatic tempering of each of the individual bearing surfaces. As will be explained later, the main bearing surfaces are hardened in a first station. In this first station the inner main bearings M2, M3, M4 can be supported by steady rest devices 30, 32 and 34; however, these devices are optional and are not necessarily employed in the hardening of the main bearings in the first station used in performing the method of the present invention. The steady rests contact the lower portion of the inner bearing surfaces 12, 14 and 16 to support these rotating surfaces by using reactive support platform 40. The first station for hardening the concentric cylindrical surfaces constituting the main bearings is followed by a second station for hardening a first group of orbiting pin surfaces and a third station for hardening a second group of the cylindrical pin surfaces. The use of two separate stations for hardening the pin bearings facilitates an aspect of the invention capable of producing a crankshaft with a total indicator run out (TIR) within a prescribed specification, such as less than 0.015 inches. The novel procedure of hardening the main bearings first and then two separate groups of pin bearings allows the TIR to be held within the desired specification. Furthermore, the apparatus and method of the present invention uses diagnostic setup procedures shown in FIG. 26 for assuring the desired tempered metallurgical characteristics around the total circumference of each of the individual cylindrical bearing surfaces.
Each of the bearing surfaces is inductively heated and then quench hardened by an inductor assembly having the structure generally described in Griebel U.S. Pat. No. 5,451,749. This type of inductor assembly is schematically illustrated as inductor B shown in FIGS. 2, 3 and more specifically in FIG. 37. Inductor or inductor assembly B is used for processing each of the cylindrical surfaces; therefore, description of one assembly applies equally to the inductor or inductor assembly used for all of the cylindrical bearings processed in accordance with the present invention. Inductor B includes a hollow, single turn conductor 50 with an arcuate configuration extending over less than 180 degrees of cylindrical bearing surface 20 being inductively heated in one embodiment. Other inductors may be employed which extend over different ranges of the surface being heated. A cooling liquid is circulated through conductor 50. Laminations 52, 54 define the extent of the arcuate heating area for conductor 50 and shoes 60, 62 and 64 locate conductor 50 around the bearing surface. Shoe 60 rides along the top of surface 20 to maintain the desired induction heating gap between conductor 50 and surface 20. This gap is designed to provide proper induction heating of rotating surface 20 in the areas opposite laminations 52, 54 Quenching liquid is directed into inductor assembly B by liquid supply lines 70, 72 so a quenching liquid is propelled against surface 20 after conductor 50 has inductively heated the surface. Inductor B has upper connector structures 80, 82 for allowing coolant liquid to flow through hollow conductor 50. Furthermore, electric power lines extend through structures 80, 82. Consequently, both coolant and electrical power is directed to inductor B. Power for the induction heating of surface 30 is provided by power source 100 including a heavy transformer and a standard power controller. The power source is supported on platform 102 having a lower inductor assembly support arm 104 for mounting the inductor B onto platform 102. Support arm 104 includes a pivoted support pin 106 and a bolted assembly 108 to maintain inductor B onto platform 102 for movement of the inductor as surface 20 orbits around axis x. In accordance with standard practice, inductor B has a counter balancing mechanism 110 reciprocally mounting the power source and inductor assembly on rails 112, 114 by an upper vertically movable dolly 116. Four spaced, pivoted straps 120 connect dolly 116 to platform 102 so that inductor B can follow along the orbital path of surface 20. Of course, an inductor having this structure when used for a main bearing will not have the orbital amount of movement of support straps or hangers 120. The main bearings still require some oscillation of the inductor. Counter balancing mechanism 110 is used to limit the force exerted by shoe 60 on surface 20. The desired force level is 15-30 pounds. Since power source 100 can weight as much as 400 pounds, counter balancing mechanism 110 must be capable of moving inductor B in a sinusoidal path. This capability is important when pin bearings are being processed, since rotation of crankshaft A causes orbital movement of the pin bearing surfaces. Main bearing surfaces do not require substantial following movement of counter balancing mechanism 110. Mechanism 110 is schematically illustrated in FIGS. 2 and 3 as including a pneumatic cylinder 130 having control input lines 132, 134 extending from controller 136 having a supply 138 of air to cause cylinder 130 to move inductor B in a vertical direction in accordance with the desired position of inductor B as crankshaft A rotates. Of course, a hydraulic system could be used for the counter balance mechanism. In accordance with the invention, the counter balancing controller 136 changes the signal on line 136a each 10 degrees arcuate movement or increment of crankshaft A. Thus, when a pin surface, such as surface 20 is being processed, cylinder 130 moves inductor B along the sinusoidal path 150, as schematically illustrated in FIG. 4. This allows a controlled force to be exerted by shoe 60 against pin surface 20. Controller 136 is updated each 10 degrees arcuate increment to control the exerted force at shoe 60 during both induction heating and quench hardening. This movement of inductor B is schematically illustrated in FIGS. 5A-5D where pin surface 20 is shown with its normal counter balancing flange 20a as shown in FIG. 1. The heavier flange 20b is combined with the thinner flange 20a to provide a heat sink for surface 20, so the bearing has a top dead center as shown in FIG. 5A and a bottom dead center as shown in FIG. 5C. As so far described, each bearing surface of crankshaft A is inductively heated and quench hardened by an inductor B with a counter balancing mechanism for the pin bearings as schematically illustrated in FIG. 4. By using the inductor with its controlled power, quenching and counter balancing, the apparatus and method are obtained, as will be explained.
Overall Installation
The apparatus and method for hardening the axially spaced cylindrical bearing surfaces of crankshaft A is performed by installation 200 schematically illustrated in FIG. 6. The production installation includes a first station 202, a second station 204 and a third station 206. These stations inductively harden selected cylindrical bearing surfaces by a method schematically illustrated in FIG. 37 for each of the individual bearing surfaces. In accordance with the invention, the main bearing surfaces are hardened first. This may be accomplished in a single first station 202, as shown in FIG. 6, or by two separate stations, combined to produce hardened main bearing surfaces for processing by stations 204, 206. In accordance with the invention, second station 204 inductively hardens inner pins P2, P3 and third station 206 hardens outer pins P1, P4. The production setup of these stations is preceded by a diagnostic procedure shown in FIG. 26 to provide desired tempered hardening over each 10 degrees arcuate increment for each of the various bearing surfaces. After that diagnostic procedure has been followed and the heating profile and the quenching and counter balancing parameters have been established, the production run as shown in FIGS. 35, 36 is implemented. Crankshaft A is processed by the equipment set forth in FIG. 6 using the values of the production run tables. A robot 210 moves crankshaft A along path 212 for loading the crankshaft into station 202 in a horizontal position between two spaced rotating centers (not shown). The centers have locator devices so station 202 rotates crankshaft A in a manner where each arcuate position is known. This locating technique is standard practice in inductively heating crank shafts. In accordance with the preferred embodiment of the invention, the five cylindrical surfaces of the main bearings are simultaneously inductively heated and quench hardened in station 202. Thereafter, robot 210 transfers crankshaft A with hardened main bearings to station 204 along path 214. In accomplishing these movements, robot 210 moves between positions 210a, 210b and 210c in accordance with standard robotic technology. In station 204, inner, orbital surfaces 22, 24 are inductively heated and then quench hardened in a manner to allow automatic tempering. It has been determined that the hardening in stations 202 and 204 produce a run out in essentially the same general direction. Consequently, before transferring shaft A to third station 206, the TIR of the main bearings is measured at auxiliary station 230. To accomplish this testing procedure, second robot 220 moves crankshaft A to the TIR measuring station 230 along path 222. This path includes a rotation movement of the robot indicated by block 222a. Thus, a horizontal crankshaft having hardened main bearings and a first group of hardened pin bearings is removed from station 204, rotated to a vertical position and then deposited in measuring station 230. After measuring the TIR of the main bearings in station 230, robot 220 moves crankshaft A along path 224 into third station 206. This path includes a rotating motion indicated by block 224a. Thus, the vertically oriented crankshaft A is moved into a horizontal position and loaded into station 206 between rotating centers with an appropriate angular identification device as used in all three stations, but not shown. If the run out measured in station 230 indicates that the end result of the TIR after hardening in station 206 will not be within the desired specification, the power for the hardening operation in station 206 is adjusted to compensate for any impending variations. Since the hardening in stations 202, 204 produce run out in the same direction, this directional run out is measured in station 230. If it is beyond a set amount, then the power in station 206 is increased If it is below a set amount, the heating in station 206 is decreased. It has been found that the TIR measured in station 230 is normally within a given range so the standard hardening procedure for the second group of cylindrical pin surfaces will bring the TIR into the desired specification. Then the crankshaft is completed. In an optional scheme shown in FIG. 6, robot 220 transfers crankshaft A along path 226 and rotates the crankshaft back to a vertical position as indicated by block 226a. The vertically oriented crankshaft is then again processed by TIR testing station 230 to determine the run out. If the run out is outside specification, crankshaft A is rejected as indicated by block 230a. When using the present invention, this event has occurred only a few times, less than 1%. Thus, crankshaft A is moved along path 228 and is rotated as indicated by block 228a. The crankshaft is now in the horizontal position and is ready for subsequent use. This is an optional arrangement since testing of TIR is normally after the crankshaft leaves installation 200.
An aspect of the invention is hardening a first group of pin bearings and then measuring the run out. Thereafter, a second group of pin bearings is hardened. If the run out after hardening the first group of pin bearings is in an area indicating that subsequent normal hardening will not bring the crankshaft back into specification, the subsequent group of pin bearings is hardened using more or less power to move the run out into specification. This procedure is an important feature of the present invention. The first group of pin bearings comprises the inner pin bearings and the second group comprises the external pin bearings. Although a first station is illustrated, as previously mentioned, the main bearings may be hardened in two groups before crankshaft A is transferred to station 204.
Quench Hardening Main Bearing
After the main bearings have been inductively heated, they are quench hardened to a temperature allowing a certain amount of automatic tempering. To accomplish the desired metallurgical characteristics and the desired run out, the quenching procedure for each main bearing surface is controlled over an arcuate increment of 10 degrees of a quench cycle amounting to several revolutions of the crankshaft. The increments are less than 30 degrees and preferably less than 20 degrees. The quench hardening protocol is disclosed in FIGS. 7-13 illustrating the quenching procedure performed in first station 202, as shown in FIG. 6. In accordance with the desired metallurgical characteristics and total run out, the main bearings are quench hardened by different liquid flow patterns, illustrated as a first sub-station 202a shown in FIG. 7 and a second sub-station 202b as shown in FIG. 8. The two separate quenching techniques are performed for different main bearings. Sub-station 202 is used for hardening main bearings 1, 3 and 5 by method 300. The main bearings are heated as indicated by block 302. Thereafter, the main bearings have a full quench flow indicated by block 304 until the surfaces are quenched and allow a certain amount of residual heat energy as indicated by block 306. During the full flow quenching of the surfaces for main bearings 1, 3 and 5, the flow of quenching liquid is controlled by valve 310 to change the amount of liquid directed from a supply of quenching liquid through quench lines 70, 72 as shown in FIG. 2. Flow valve 310 is controlled pneumatically by controller 314 and includes set flow volume positions indicated and activated as numbers. The output number for controller 314 is determined by an open loop technique reviewed each 10 degrees of rotation of crankshaft A as detected by sensor 316. Each of the individual shafts hardened in sub-station 202a has its own full flow quenching pattern, as set forth in FIGS. 9, 11 and 13. At the same time, sub-station 202b of first station 202 performs method 320 for quench hardening the intermediate bearings M2 and M4. By method 320, the two main bearings are heated as indicated by block 322 and are quenched by a pulse quenching operation illustrated as block 324. This quench hardening procedure using pulse quenching maintains a low total run out caused by hardening the intermediate bearings. Method 310 includes a subsequent tempering operation shown by block 326 so the quench hardening procedure results in a residual heat energy allowing a slight tempering action after the liquid quenching has been concluded. Flow valve 330 has a controller 334, which has a set number provided by angular sensor 336 reading arcuate increments, which in practice are 10 degrees. By using a full flow quenching of the outside and center main bearings and pulsed quenching in the intermediate main bearings, the total run out is somewhat controlled and appears in a given, known direction. Methods 300, 320 are performed at station 202 and the 10 degree measurements of sensors 316, 336 are the rotational positions of the crankshaft Use of these methods produces quenching operations shown schematically in FIGS. 9-13. In FIG. 9, a full quench flow as indicated by curve 350 is used for main bearing M1 processed as a closed loop process using sensor 316 as shown in FIG. 7. Spike 352 appears at the end of the quenching because of the turn off inertia. For main bearing M2, the quenching procedure shown in FIG. 8 is employed to produce a flow curve 360 having pulsed quenching portion 362. These portions allow the intermediate bearing to hold the two adjacent bearing surfaces more nearly centered. A full quenching operation for main bearing M3 is shown as curve 370 in FIG. 11. A pulsed quenching operation is shown in curve 380 in FIG. 12 having pulsed portions 382 for main bearing M4. The final main bearing M5 has a full quench flow as curve 390 in FIG. 7. FIGS. 7-13 illustrate the preferred embodiment for quench hardening the main bearings in station 202 to produce a desired small run out, which run out is known to be in a given direction with respect to the various counter balancing flanges of crankshaft A.
Quench Hardening of Pin Bearings
The pin bearings are quench hardened in stations 202, 204 of FIG. 6 utilizing a pulsed quenching procedure that is novel and is illustrated as method 400 in FIG. 14. The pin bearing is heated with a power profile that is changed every 10 degrees of rotation of the crankshaft, as indicated by block 402. The increments are less than 30 degrees and preferably less than 20 degrees. But in practice they are about 10 degrees. Thereafter, there is a full flow quench portion, as indicated by block 404. After a short full quench procedure, flow controller, such as controller 334, 336 shown in FIG. 8, is used to produce pulses of quenching fluid by changing the number for the flow valve 330. This procedure illustrated as block 406 is continued until the pin bearing surface is hardened to a desired amount while allowing a certain amount of residual heat energy to provide a slight tempering, as indicated by block 408. Thus, each of the pins is first quench hardened with a full flow and then quenched with a series of liquid pulses. As indicated by block 410, preferably these quench pulses are in a closed loop and controlled by the rotation of crankshaft 10 through a given arcuate increment which is preferably 10 degrees. However, they may be done in an open loop control. By providing pulsed quenching, the metallurgical characteristics of the pin bearing surfaces is maintained in the desired range and there is a uniform effect upon the resulting run out. The quench flow curves for the various pins are set forth in FIGS. 15-18. Pin P1 is quench hardened by liquid flow illustrated as curve 420 in FIG. 15. Curve 422 shown in FIG. 16 is employed for pin P2. The third pin P3 utilizes liquid flow represented by curve 424 in FIG. 17 and the final pin P4 is quench hardened by quench liquid flow as represented by curve 426 in FIG. 18. Each of these curves include a full quenching segment or portion 430 using the method set forth in FIG. 7 and then a pulsed quench liquid flow as created by the procedure set forth in FIG. 8. When coordinating the quenching of the pin surfaces with the rotation of the crankshaft, the pulses 432 are coordinated with the top dead center of the pin and the crest between the pulses is coordinated with the bottom dead center of the pin. FIGS. 14-18 illustrate a novel aspect of the present invention wherein the crank pins in the two separate hardened groups of station 204 and 206 utilizes a quenched flow that is first continuous and then pulsed. This provides uniformity of run out and also allows cooling coordinated with the necessary heating at both the top dead center and the bottom dead center of the crank pin as it rotates.
Control of Run Out
The apparatus and method of the present invention controls the extent of final run out for crankshaft A by first hardening main bearings either in two separate stations or, preferably, in a single station 202. By a procedure set forth in FIGS. 19-21, the run out for the operation of station 202, the run out for station 204 and the run out for station 206 is known so that these known physical characteristics of the heating operation are used to create a crankshaft that is hardened and also has minor total indicator run out. To determine the direction of run out caused by hardening of the pins, test pins are hardened as a group and tested according to method 450, shown in FIG. 19. This method involves taking several crank shafts and hardening a group of pins, such as pins P2 and P3 or pins P1 and P4. This process is indicated by block 452. After the pins have been hardened, the run out of the shaft is tested by a total indicator run out (TIR) station, such as station 230 used in FIG. 6. This testing procedure is set forth in block 454 and is followed by displaying the actual pattern run out for the many shafts tested. The run out is determined after the group of pins has been hardened. This run out is plotted on circular chart 460 as shown in FIG. 21. Measured run out points are plotted on chart 460 as indicated by the many dots 462. The grouping of the dots is concentrated in areas 470 to give a mean run out RO for the crankshaft when a given group of pins is hardened. This run out is used in performing the method, as explained in connection with the installation layout of FIG. 6. By performing the method 450 on the two separate groups of pin bearings, it has been found that one group of pin bearings has a positive run out RO and the other group has a negative run out RO. This discovery is used in the invention for limiting run out. The same testing method is implemented to determine shaft run out after only the main bearings have been hardened. This main bearing run out testing method is illustrated as method 480 in FIG. 20. The main bearings are hardened as indicated by block 482. The shaft TIR is measured as indicated by block 484 and is displayed as a pattern on circular chart 460 shown in FIG. 21. This determines the run out for the main bearings. It has been found that the main bearing run out is in one direction indicated to be positive and the two pin bearing run out RO are positive for the bearing group containing pins P2 and P3. The run out caused by hardening pins P1 and P4 is a negative run out. For this reason, the first group of pins is hardened in station 204 and the second group of pins is hardened in station 206. Consequently, the run out for the first group is added to the run out for the main bearings and is compensated for by run out experienced in the second group of hardened pins. This procedure is shown in FIGS. 22 and 23, as previously described. Station 202 or combined stations 202a, 202b hardens all of the main bearing surfaces. This produces a run out direction referred to as positive. Then, station 204 is used to harden the first group of pins that have been determined to present a run out in the same direction as the main bearing run out. To compensate for the run out experienced at station 204, the hardening procedure at station 206 provides compensation and, thus, corrects the shaft run out to produce a crankshaft within the run out specification. In accordance with this aspect of the invention, by measuring the run out of the crankshaft after station 204, the heating procedure or profile in station 206 is adjusted to assure that the compensation by the hardening procedure in station 206 is such to overcome extreme run out caused by hardening in stations 202, 204. The crankshaft is relatively straight so subsequent straightening is not required. The procedure for controlling the run out is summarized in FIG. 24 wherein the hardened pins P2 and P3 in station 204 produces a run out as determined by use of measuring station 230. If the total positive run out is greater than a given value, the amount of power used in station 206 is increased If the measured run out is less than a certain value, then the standard power for station 206 is reduced. This power adjustment procedure is indicated by block 500 in FIG. 24. Thereafter, station 206 is used to harden pins P1 and P4 with the adjusted amount of power. This procedure is made possible because the run out in stations 202 and 204 are in one direction and the run out in station 206 is in the other direction. This concept is schematically shown in FIG. 25 wherein step 510 adjusts the amount of run out in the direction created in station 206 to compensate for the measured run out at station 230. The selection of determined consistent run out in the various stations is used to implement one aspect of the invention which aspect produces a crankshaft with a low amount of total indicator run out.
Diagnostic Profiling
Another aspect of the invention provides methods for induction hardening internal combustion engine crankshaft bearing surfaces using tuned profiles for angularly incremented provision of power, quenching fluid, and inductor counter balancing as the treated crankshaft is rotated about the main bearing axis, by which an induction hardening process can be tailored to achieve a desired post-hardening metallurgy. This technique involves induction hardening one or more test crank shafts using initial profiles for power, quenching fluid flow rate, and/or inductor counterbalancing force which measuring various actual process values, such as applied inductor voltages, currents, quench flow rates, etc. at each associated control increment, and thereafter measuring one or more post-hardening crankshaft characteristics, such as hardened surface metallurgy, crankshaft TIR, and/or markings on the counter balance apparatus (e.g., shoe markings). One or more of the power, quench flow, and/or counter balance profiles are then adjusted according to one or more of the measured process profiles and/or crankshaft characteristics, and thereafter further crank shafts are hardened using the adjusted profiles. The process may be repeated any number of times to establish an optimized set of profiles for use in production hardening to achieve the desired metallurgical characteristics of a tempered hardened surface without requiring subsequent heat treatment of the bearing surfaces. One example is illustrated in FIG. 26 with respect to applied power profile adjustment based on measured metallurgy in accordance with this aspect of the invention, wherein similar techniques may be employed with respect to more than one profile with adjustments being made based on one or more measured crankshaft characteristics and/or based on one or more measured process parameter. The example of FIG. 26 employs a diagnostic profiling technique 600 to create a profile for the level of the power at each 10 degrees arcuate increment over 360 degrees. This power profile stored in area 602 is digitized as a menu or look up table in memory device 604. Thus, the profile in device or area 602 sets the level of signals from a data table in memory device 604. The data is outputted at specific angular segments as crankshaft A is rotated. During the setup procedure before the production run, a particular bearing surface is heated in accordance with a power profile stored device 602. The resulting hardened surface is analyzed metallurgically in a laboratory to determine the metallurgical characteristics around the bearing surface. This procedure is represented as laboratory procedure 606. To the extent that the surface does not have the desired characteristics at all locations, the power profile is modified or adjusted. The interactive diagnostic procedure is continued by changing the look up table in memory device 604 and testing the metallurgy. This process is repeated many times for each bearing surface before a power profile for production is created. The heating cycle around 360 degrees of each bearing surface is controlled by an ultimately created profile. After the profile has been created and transferred to the look up table, the table controls the heat cycle to accomplish the desired metallurgical results. At this time, the heat profile is finalized for use in production. Memory device or look up table 604 is used to control the power supply. A closed loop system 610 controls the power source. The angle of rotation sensed by device 612 addresses the look up table in memory device 604 to produce the desired output signal 614 for each 10 degrees arcuate increment. The increments are less than 30 degrees and preferably less than 20 degrees. In practice they are about 10 degrees. The profile for heating the pins is set forth in FIGS. 27-30 wherein the heating power around the crankshaft has the power profiles 620, 622, 624 and 626 for pins P1, P4, P2 and P3, respectively. As shown, pins P1 and P4 are heated by profiles that are generally mirror images, since they are at opposite sides of the rotational axis of crankshaft A. In a like manner, the power profiles 624, 626 of pins P2 and P3 have power profiles that are generally mirror images of each other. They are also on opposite sides of the crankshaft. The power profiles 630, 632 and 634 for the main bearing surfaces are illustrated in FIGS. 31, 32 and 33. As can be seen, the power profiles 630, 632 for heating bearing surfaces M1, M3 and M5 are essentially constant power, whereas main bearings M2 and M4 have profiles that are pulsed, according to the rotational position of the crankshaft. Pulsing power supply is beneficial, since the main bearings M2 and M4 have counter balancing flanges on both sides.
The heat or power profile are repeated over 360 degrees of rotation and are monitored for changing each arcuate increment, which is less than 30 degrees and more particularly less than 20 degrees. In practice the increments are about 10 degrees. This is shown for one pin in FIG. 34 where a typical voltage profile for a total heating cycle of a pin is shown as curve 640 with high heating 646 at bottom dead center of the pin and low heating 644 at top dead center of the pin.
The signal levels of heating, as well as adjusted quenching and counter balance, for the pin bearings are provided in the table shown in FIG. 35. These values have been generated using the metallurgical adjustment of the diagnostic scheme illustrated in FIG. 26 for the heating profiles. The values for the various signals at each of the 10 degrees arcuate increments for quenching and counter balance are also determined diagnostically before the table of signals is used for production. Main bearings use the heating profiles and other levels as shown in the table of FIG. 36. Diagnostic procedures generate signals to determine the power, quench flow and counter balance position at 10 degrees increments of the rotating crankshaft, wherein one or more process profiles may be adjusted automatically or manually to refine the induction hardening process.
System
The general system of the present invention for each hardening station used in installation 200 of FIG. 6 is schematically illustrated in FIG. 37, The desired values for all angular positions are illustrated by one example shown in the tables of FIGS. 35 and 36. The positions of the tables are for a single rotation of the surfaces, as used for the power profiles set forth in FIGS. 27-33. Heating and counter balancing is generally related to a single rotation of the crankshaft. Quenching is performed over several rotations of the crankshaft. However, the pulsing procedure for after a full flow quench is also pulsed repeatedly over 360 degrees of the surface to match TDC and BDC. A system operated in accordance with the present invention is shown in FIG. 37. Crankshaft hardening system 700 for each of the surfaces includes a quench chamber 710, 712 associated with inductor B and having flow valve 720 operated by controller 722 in accordance with the input signal to the controller. In a like manner, the heat energy for induction heating by inductor B is provided by power source 730 operated through transformer 732. The level of output power is determined by controller 734 that is adjusted for each arcuate increment of the rotational motion of crankshaft A. As previously described, counter balancing mechanism 740 has a position controller 742 for adjusting the position or force exerted by shoe 60 on the bearing surface. A resolver 746 determines the exact angular position of the crankshaft and drives output 748. This increments look up table or data table 750. The table contains levels for each 10 degrees arcuate increment as illustrated by a representative process having the control signal levels of the tables in FIGS. 35 and 36. These levels are used over 360 degrees for heating and counter balance. They are the levels of quench liquid flow during pulse quenching of pins P1-P4 and main bearings M2 and M4. In accordance with the levels shown in the control tables of FIGS. 35 and 36 memory device 750 creates specific signals in lines 752, 754 and 756 for periodically updating controllers 722, 734 and 742, respectively. System 700 operates in accordance with the tables set forth in FIGS. 35 and 36 to process specific bearing surface in stations 202, 204 and 206, as shown in FIG. 6. In this manner, the metallurgical characteristics of the surfaces are maintained, while also providing a relatively straight crankshaft without straightening required.
Patent Application
20080041844
