EP0064367B1 - Method for inductively heating valve seat inserts - Google Patents
Method for inductively heating valve seat inserts Download PDFInfo
- Publication number
- EP0064367B1 EP0064367B1 EP82302088A EP82302088A EP0064367B1 EP 0064367 B1 EP0064367 B1 EP 0064367B1 EP 82302088 A EP82302088 A EP 82302088A EP 82302088 A EP82302088 A EP 82302088A EP 0064367 B1 EP0064367 B1 EP 0064367B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- valve seat
- insert
- inductor
- energizing
- engine component
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
- F01L3/22—Valve-seats not provided for in preceding subgroups of this group; Fixing of valve-seats
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
Definitions
- This invention relates to the art of induction heating and, more particularly, to a method for inductively heating valve seat inserts for an engine component such as an engine head or the like.
- the invention is particularly applicable to heating exhaust valve seat inserts in a cast aluminum engine component and will be described with particular reference thereto; however, it will be appreciated that the invention has broader applications.
- valve seats which coact with reciprocating poppet valves for controlling the flow of gases to and from the engine cylinders.
- the valve seats for the exhaust valves must have extremely high wear characteristics at high engine operating temperatures.
- the frusto-conical seat surfaces are inductively heated during engine manufacture and then quench hardened by conventional liquid or mass quenching techniques.
- Induction heating of multiple valve seats in an engine component may be adapted to automatic processing in a single operation where, for example, a plurality of single turn inductors are positioned immediately adjacent the frusto-conically shaped exhaust valve seat.
- Such apparatus and methods are disclosed in US-E-29,046 and . US-A-3,837,934 to which reference is directed.
- the inductors are independently movable on a common frame relative to the engine component and are biased toward the valve seats.
- the frame itself is moved into contact with the engine component so that each inductor contacts the valve seat which it is to heat.
- the inductors are then locked in position and the frame retracted slightly for purposes of establishing a desired magnetic coupling distance between the inductors and valve seats. After heating, the valve seat -material is quenched.
- the foregoing patents disclose methods which have provided extremely good results when induction heating ferrous exhaust valve seats in cast iron engine components.
- the present invention provides an alternative method of hardening a valve seat on a ferrous valve seat insert located in a bore of an engine component using inductive heating, in which the above-mentioned problems caused by heating the valve seat surface to its hardening temperature whilst the insert is located in the engine component bore are overcome by the controlled application of high frequency power in the inductive heating of the valve seat surface.
- the present invention includes a method of hardening a frusto-conical valve seat on a ferrous valve seat insert retained with a pressure fit within a bore of an engine component said method comprising the steps of:
- the invention is especially advantageous where the engine component is non-ferrous particularly, as stated above, where the engine component is aluminum.
- the invention also includes a method of hardening a frusto-conical valve seat on a ferrous valve seat insert coaxially fixed in a bore of an aluminum engine component, said method comprising the steps of:
- FIGURE 1 shows an induction heating device A disposed in operative communication with a cast aluminum engine component B. Specific details of the features and operation of induction heating device A are disclosed in detail in our US-E-29046.
- engine component B includes at least one exhaust passageway 10 having an annular valve seat insert 12 formed of cast iron and closely disposed coaxially within a recessed cylindrical exhaust port 14.
- a guide opening or port 16 is coaxial with exhaust port 14 and receives the stem of a conventional poppet valve (not shown) when the engine is assembled.
- Annular valve seat insert 12 includes a frusto-conically shaped valve seat surface 30 which is installed into the engine component, machined and thereafter hardened.
- Insert 12 comprises a standard component typically constructed from steel or cast iron; however, cast iron is preferred because of costs.
- Installation of insert 12 into the receiving bore at exhaust port 14 may be by any one of a number of conventional methods including, for example, a pressure or force fit and the like. When a pressure fit technique is employed, the insert is normally chilled to obtain some degree of contraction and thereby more readily accommodate installation. Following installation, the insert is fixedly retained in port 14 by opposed forces particularly occurring at interface area 32 between the outer side wall of the insert and the receiving bore side wall. It will be readily appreciated that a plurality of exhaust ports with associated inserts A are typically involved with any engine component Bin the same manner best described in U.S. Pat. No. Re 29.046.
- induction heating device A includes a generally cylindrical electrically insulated body 40 having a somewhat smaller cylindrical electrically insulated body insert 42 extending coaxially outward from the inner end thereof.
- a locating pin or nose 44 extends coaxially outward from body insert 42 to accommodate locating the induction heating device coaxially of exhaust port 14 in a known manner.
- a single turn inductor Interposed between body 40 and body insert 42 of the induction heating device is a single turn inductor generally designated 50.
- This inductor comprises a split circular ring of copper of generally rectangular cross-section and includes a pair of spaced legs 52, 54 extending therefrom axially through body 40 and outwardly from the body outer end.
- Inductor 50 as well as legs 52, 54 are hollow and communicate with each other in such fashion to define a continuous fluid passageway therethrough. This passageway accommodates passage of a suitable coolant from a source (not shown) disposed adjacent to or spaced from the overall induction heating device as is known.
- a power source 60 is operatively connected by leads 62, 64 to inductor 50 as at, for example, legs 52, 54, respectively.
- the power source comprises an oscillator having an output frequency capability generally in the range of 200-500 kilohertz (kHz) and a power capability of generally between 12-25 kilowatts (kW).
- kHz kilohertz
- kW kilowatts
- the preferred power is approximately 20 kW.
- the power density is in the general range of 24 to 50 kW/m 2 (3.72 to 7.7 kW/cm 2 ) and is preferably 40 kW/in 2 (6.2 kW/cm 2 ). This is drastically higher than any power density previously used for heating the valve seats of internal combustion engines.
- a time delay device is advantageously incorporated between leads 62, 64 for turning the power source 60 off after a preselected heating time or interval. This heating time is quite short and less than 1 second.
- aluminum engine component B will typically have a plurality of exhaust ports 14 which all have similar inserts 12 which are to be inductively heated in a simultaneous manner.
- Apparatus adapted for this purpose is shown in US-E-29,046 and includes means for causing induction heating device A to be positioned in an associated exhaust port 14 with locating pin 44 coaxially aligning the device relative to the exhaust port.
- Device A is bottomed out with inductor 50 engaging conical valve seat surface 30 of seat insert 12. Thereafter, the heating device is backed out slightly so that some preselected gap is present between the inductor and frusto-conical valve seat surface 30 to effect a desired coupling relationship therebetween.
- this gap is generally designated by letter g and comprises a distance of approximately 0.040 inches (1 mm). While this particular gap has been found particularly suitable in most cases where a ferrous valve seat insert disposed in an aluminum engine component is to have a frusto-conical valve seat surface hardened, it will be appreciated that it may be varied somewhat as deemed necessary or appropriate for a specific application of the new method.
- the side or flat surface 70 of inductor 50 is generally parallel to seat surface 30 and has a width at least slightly greater than that of the seat surface.
- a high power, low time induction heating method is employed whereby seat surface 30 of seat insert 12 is sufficiently heated to an acceptable depth for purposes of transforming the seat material into the austenitic range for subsequent transformation into the martensitic range.
- the depth of such transformation is generally designated by the letter d and may comprise a depth of up to approximately 0.035 inches (0.89 mm), although 0.024 inches (0.61 mm) is generally preferred.
- a relatively shallow reference depth is heated in the seat surface and by using the preferred power of approximately 20 kW to obtain a power density of about 40 kW/in 2 (6.2 kW/cm 2 ), the valve seat is heated to an acceptable transformation temperature at a very rapid rate. Indeed, and when using the preferred ranges noted, it has been found that a time interval of approximately 0.5 seconds will provide entirely satisfactory heating and hardening results to a depth of approximately 0.024 inches (0.61 mm).
- the seat rings or the entire engine component are subjected to quenching in a manner known in the art. Because heating of seat surfaces 30 is so rapid and is substantially limited to or isolated at these surfaces to a preselected shallow depth, there is no deleterious heating of the whole insert or heat transfer through seat inserts 12. These factors might otherwise adversely affect or alter the close fitting relationship between the seat inserts and exhaust ports. This result represents a substantial improvement over results obtained from prior known techniques in inductively heating valve seats or valve seat inserts.
- cast iron valve seat inserts have been successfully hardened to a case depth of 0.030 inches (0.76 mm) using a heat cycle of 0.5 seconds with a radio frequency oscillator (400 kHz) and a power density of 40 kW/in 2 (6.2 kW/cm z ).
- the advantages of using a soft cast iron insert in an aluminum cylinder head rather than a prehardened alloy steel insert resides in the fact that it permits easy machining of the soft cast insert with subsequent hardening of the valve seat by induction hardening techniques. This then achieves the requisite seat durability while, at the same time, yielding considerable improvement by way of increased productivity.
- Valve seat inserts have also been hardened at a 0.2 second heat time with this new method to approximately the case depth of 0.030 inches (0.76 mm) by using considerably more than 40 kW/in 2 (6.2 kW/cm 2 ) power density. Even though it reduces the tendency to induce heat into the insert, the 0.5 second heating cycle is considered somewhat more tolerable in that it provides a more uniform and constant case depth.
- the preferred parameters of the subject method using a primary power source having a frequency of approximately 400 kHz and a power of approximately 20 kW with a heating cycle of approximately 0.5 seconds provides a case depth of approximately 0.024 inches (0.61 mm) and a hardness of "58" on the Rockwell C scale in cast iron seat inserts.
- Prior techniques which typically employ the same frequency at a power of approximately 7 kw with a heating cycle of approximately 7-8 seconds provides a case depth of between 0.050-0.060 inches (1.27-1.52 mm) and a hardness of "58" on the Rockwell C scale.
- Such parameters, while acceptable for gray cast iron engine components having integral cast iron valve seats simply will not provide suitable results in the environment of cast aluminum engine components utilizing ferrous seat ring inserts.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Heat Treatment Of Articles (AREA)
- Details Of Valves (AREA)
- Lift Valve (AREA)
- General Induction Heating (AREA)
Abstract
Description
- This invention relates to the art of induction heating and, more particularly, to a method for inductively heating valve seat inserts for an engine component such as an engine head or the like.
- The invention is particularly applicable to heating exhaust valve seat inserts in a cast aluminum engine component and will be described with particular reference thereto; however, it will be appreciated that the invention has broader applications.
- Internal combustion engines generally employ frusto-conically shaped valve seats which coact with reciprocating poppet valves for controlling the flow of gases to and from the engine cylinders. The valve seats for the exhaust valves must have extremely high wear characteristics at high engine operating temperatures. To counteract such wear and increase desirable physical properties in the valve seats, the frusto-conical seat surfaces are inductively heated during engine manufacture and then quench hardened by conventional liquid or mass quenching techniques.
- Induction heating of multiple valve seats in an engine component may be adapted to automatic processing in a single operation where, for example, a plurality of single turn inductors are positioned immediately adjacent the frusto-conically shaped exhaust valve seat. Such apparatus and methods are disclosed in US-E-29,046 and . US-A-3,837,934 to which reference is directed. There, the inductors are independently movable on a common frame relative to the engine component and are biased toward the valve seats. The frame itself is moved into contact with the engine component so that each inductor contacts the valve seat which it is to heat. The inductors are then locked in position and the frame retracted slightly for purposes of establishing a desired magnetic coupling distance between the inductors and valve seats. After heating, the valve seat -material is quenched. The foregoing patents disclose methods which have provided extremely good results when induction heating ferrous exhaust valve seats in cast iron engine components.
- However, recent efforts to improve gasoline mileage and obtain vehicle weight reductions have brought about an ever increasing use of aluminum for major engine components. Although use of aluminum for manufacturing such major components provides substantial benefits insofar as weight reduction is concerned, attendant difficulties and problems have been encountered in several areas, including exhaust valve seats. Aluminum does not have sufficient strength and hardness properties to itself accommodate or comprise the valve seat surfaces. As a result of these shortcomings, it is necessary that the exhaust valve seat surfaces be provided through use of seat ring inserts constructed of a hardenable material installed in the cast aluminum engine component by suitable means such as, for example, a force fit or the like. For cost reduction purposes as well as for purposes of assuring accurate location and concentricity of the valve seat surfaces, it is highly desirable that machining of the inserts for obtaining final valve seat conformation takes place subsequent to mounting of the inserts into the engine component.
- While machining of the frusto-conical valve seat surfaces does not present any significant problems, subsequent surface hardening must be performed in a manner which will not deleteriously affect the aluminum engine component and/or the pressure fit between the engine component and the ferrous metal insert. Because it is customarily necessary to harden exhaust valve seat surfaces at approximately 1700°F (927°C) and since the melting point of typical aluminum alloys employed for engine components is generally in the range of 1200°-1400°F (649-760°C), heating of and heat transfer through the seat inserts must be carefully controlled during the hardening process. Without appropriate control, the inserts may radially expand against the associated receiving bores in the engine component to destroy the pressure fit relationship therebetween and/or otherwise damage the integrity of the engine component metal adjacent thereto. In more severe cases, the aluminum engine component metal could be unacceptably brought close to its melting temperature. Both of the foregoing situations are extremely undesirable in that they can ultimately adversely affect engine operation or expected engine life. The specific heating conditions disclosed in US-E-29,046 and US-A--3,837,934 are useful in inductively heating valve seats and valve seat insert surfaces when conventional gray cast iron engine components are involved. They are not, however, as effective for use with aluminum or the like components because of the above noted problems and characteristics which are generally associated therewith. In view of these factors, the inserts were often made of expensive steel and hardened in furnaces before assembly into the engine com- 'ponent. This involves costly materials as well as costly post assembly machining of the hardened seat inserts.
- It has, therefore, been considered desirable to develop a method for inductively heating the seat surface of ferrous seat ring inserts installed in respective recesses, or bores, of engine components for purposes of overcoming the foregoing problems. One such method and apparatus is disclosed in our EP-A-41317, published after the priority date of the present applications, in which a conducting ring in operative association with each heating inductor is used to protect the interface between the insert and engine com- ponentfrom heating to a temperature sufficient to loosen the insert from the recess during inductive heating of the valve seat surface.
- The present invention provides an alternative method of hardening a valve seat on a ferrous valve seat insert located in a bore of an engine component using inductive heating, in which the above-mentioned problems caused by heating the valve seat surface to its hardening temperature whilst the insert is located in the engine component bore are overcome by the controlled application of high frequency power in the inductive heating of the valve seat surface.
- The present invention includes a method of hardening a frusto-conical valve seat on a ferrous valve seat insert retained with a pressure fit within a bore of an engine component said method comprising the steps of:
- (a) locating a generally circular inductor adjacent to and matching said insert;
- (b) controlling the energization of said inductor at a frequency of between 200 and 500 kHz, a selected power of 12 to 25 kW, a power density at the seat of between 24 to 50 kW/in (3.72 to 7.7 kW/cm2) and for a period of time less than 1 second, thereby to transform the metal forming said valve seat into an austenitic structure to some predetermined depth; and
- (c) thereafter quenching said valve seat material.
- The invention is especially advantageous where the engine component is non-ferrous particularly, as stated above, where the engine component is aluminum. Specifically, the invention also includes a method of hardening a frusto-conical valve seat on a ferrous valve seat insert coaxially fixed in a bore of an aluminum engine component, said method comprising the steps of:
- (a) locating a generally circular inductor adjacent said insert;
- (b) energizing said inductor with a primary power source having a frequency of at least 200 kHz and a selected power of at least 12 kW and producing a power density at the seat of between 25 to 45 kW/in2 (3.875 to 6.975 kW/cm2);
- (c) maintaining said inductor in an energized condition for a preselected period of time for transforming the metal forming said valve seat into an austenitic structure to a depth less than 0.035 inches (0.89 mm); and
- (d) thereafter quenching said valve seat material.
- DE-B-1,035,179 which has been drawn to our attention by the European Patent Office during the prosecution of this application discloses a method of hardening a valve seat in a ferrous cylinder head using inductive heating, which is carried out at a power level of 75 kW at a frequency of 360 kHz over two periods of time, the first being a few hundredths of a second in duration and the second being 0.35 seconds long, the valve seat material thereafter being quenched. This specification also refers to the hardening of ferrous valve seat inserts in a ferrous engine head, but does not disclose a different power level for the hardening of such an insert. No power density values are given in DE-B-1,035,179, but assuming a valve seat area of about 0.5 in2 (3.23 cm2) - i.e. the same as that in the exemplary embodiment of the present invention, described hereinafter - the power density would be about 150 kW/in2 (23.1 kW/cm2). That is at least 300 per cent greater than the maximum power density used in the present invention.
- In order that the invention may be well understood an embodiment thereof, which is given by way of example only, will now be described in more detail with reference to the accompanying drawings, in which,
- FIGURE 1 is a partial cross-sectional view illustrating the preferred manner of practicing the subject new method; and,
- FIGURE 2 is an enlarged cross-sectional view of a portion of FIGURE 1 for better showing the relationship between the inductor and valve seat surface to be heated.
- Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting same, FIGURE 1 shows an induction heating device A disposed in operative communication with a cast aluminum engine component B. Specific details of the features and operation of induction heating device A are disclosed in detail in our US-E-29046.
- More particularly, engine component B includes at least one
exhaust passageway 10 having an annular valve seat insert 12 formed of cast iron and closely disposed coaxially within a recessedcylindrical exhaust port 14. A guide opening orport 16 is coaxial withexhaust port 14 and receives the stem of a conventional poppet valve (not shown) when the engine is assembled. - Annular
valve seat insert 12 includes a frusto-conically shapedvalve seat surface 30 which is installed into the engine component, machined and thereafter hardened.Insert 12 comprises a standard component typically constructed from steel or cast iron; however, cast iron is preferred because of costs. Installation ofinsert 12 into the receiving bore atexhaust port 14 may be by any one of a number of conventional methods including, for example, a pressure or force fit and the like. When a pressure fit technique is employed, the insert is normally chilled to obtain some degree of contraction and thereby more readily accommodate installation. Following installation, the insert is fixedly retained inport 14 by opposed forces particularly occurring atinterface area 32 between the outer side wall of the insert and the receiving bore side wall. It will be readily appreciated that a plurality of exhaust ports with associated inserts A are typically involved with any engine component Bin the same manner best described in U.S. Pat. No. Re 29.046. - Continuing with reference to FIGURE 1, induction heating device A includes a generally cylindrical electrically insulated
body 40 having a somewhat smaller cylindrical electrically insulatedbody insert 42 extending coaxially outward from the inner end thereof. A locating pin ornose 44 extends coaxially outward frombody insert 42 to accommodate locating the induction heating device coaxially ofexhaust port 14 in a known manner. - Interposed between
body 40 andbody insert 42 of the induction heating device is a single turn inductor generally designated 50. This inductor comprises a split circular ring of copper of generally rectangular cross-section and includes a pair ofspaced legs body 40 and outwardly from the body outer end.Inductor 50 as well aslegs - A
power source 60 is operatively connected by leads 62, 64 toinductor 50 as at, for example,legs conductor 50. Also, the preferred power is approximately 20 kW. Since the heated area ofconical surface 30 is about 0.5 in2 (3.23 cm2), the power density is in the general range of 24 to 50 kW/m2 (3.72 to 7.7 kW/cm2) and is preferably 40 kW/in2 (6.2 kW/cm2). This is drastically higher than any power density previously used for heating the valve seats of internal combustion engines. A time delay device is advantageously incorporated betweenleads power source 60 off after a preselected heating time or interval. This heating time is quite short and less than 1 second. - In practicing the new method, aluminum engine component B will typically have a plurality of
exhaust ports 14 which all havesimilar inserts 12 which are to be inductively heated in a simultaneous manner. Apparatus adapted for this purpose is shown in US-E-29,046 and includes means for causing induction heating device A to be positioned in an associatedexhaust port 14 with locatingpin 44 coaxially aligning the device relative to the exhaust port. Device A is bottomed out withinductor 50 engaging conicalvalve seat surface 30 ofseat insert 12. Thereafter, the heating device is backed out slightly so that some preselected gap is present between the inductor and frusto-conicalvalve seat surface 30 to effect a desired coupling relationship therebetween. - With reference to FIGURE 2, this gap is generally designated by letter g and comprises a distance of approximately 0.040 inches (1 mm). While this particular gap has been found particularly suitable in most cases where a ferrous valve seat insert disposed in an aluminum engine component is to have a frusto-conical valve seat surface hardened, it will be appreciated that it may be varied somewhat as deemed necessary or appropriate for a specific application of the new method. The side or
flat surface 70 ofinductor 50 is generally parallel toseat surface 30 and has a width at least slightly greater than that of the seat surface. - It is necessary to prevent deleterious heating of or heat transfer through the entirety of
insert 12 in the preferred environment here under discussion. It has been discovered that acceptable heating results could be obtained ifseat surface 30 was quickly brought to temperature and then quenched prior to the time that any deleterious heat transfer could occur. Moreover, it is necessary at the same time to obtain a suitable depth of heating to assure that the hardened seat surface will have sufficiently high wear characteristics at high operating temperatures. To that end, it has also been discovered that a depth of generally no greater than 0.035 inches (0.89 mm) will provide wholly satisfactory results without in any way impairing engine operation or engine life. In practice, a depth of approximately 0.024 inches (0.61 mm) has been found entirely satisfactory and is preferred when using the subject new method. - Thus a high power, low time induction heating method is employed whereby
seat surface 30 ofseat insert 12 is sufficiently heated to an acceptable depth for purposes of transforming the seat material into the austenitic range for subsequent transformation into the martensitic range. As shown in FIGURE. 2, the depth of such transformation is generally designated by the letter d and may comprise a depth of up to approximately 0.035 inches (0.89 mm), although 0.024 inches (0.61 mm) is generally preferred. By using the preferred frequency of approximately 400 kHz, a relatively shallow reference depth is heated in the seat surface and by using the preferred power of approximately 20 kW to obtain a power density of about 40 kW/in2 (6.2 kW/cm2), the valve seat is heated to an acceptable transformation temperature at a very rapid rate. Indeed, and when using the preferred ranges noted, it has been found that a time interval of approximately 0.5 seconds will provide entirely satisfactory heating and hardening results to a depth of approximately 0.024 inches (0.61 mm). - On completion of the induction heating cycle, the seat rings or the entire engine component are subjected to quenching in a manner known in the art. Because heating of seat surfaces 30 is so rapid and is substantially limited to or isolated at these surfaces to a preselected shallow depth, there is no deleterious heating of the whole insert or heat transfer through seat inserts 12. These factors might otherwise adversely affect or alter the close fitting relationship between the seat inserts and exhaust ports. This result represents a substantial improvement over results obtained from prior known techniques in inductively heating valve seats or valve seat inserts.
- In using the foregoing new method, cast iron valve seat inserts have been successfully hardened to a case depth of 0.030 inches (0.76 mm) using a heat cycle of 0.5 seconds with a radio frequency oscillator (400 kHz) and a power density of 40 kW/in2 (6.2 kW/cmz). The advantages of using a soft cast iron insert in an aluminum cylinder head rather than a prehardened alloy steel insert resides in the fact that it permits easy machining of the soft cast insert with subsequent hardening of the valve seat by induction hardening techniques. This then achieves the requisite seat durability while, at the same time, yielding considerable improvement by way of increased productivity.
- Valve seat inserts have also been hardened at a 0.2 second heat time with this new method to approximately the case depth of 0.030 inches (0.76 mm) by using considerably more than 40 kW/in2 (6.2 kW/cm2) power density. Even though it reduces the tendency to induce heat into the insert, the 0.5 second heating cycle is considered somewhat more tolerable in that it provides a more uniform and constant case depth.
- By way of comparison, the preferred parameters of the subject method using a primary power source having a frequency of approximately 400 kHz and a power of approximately 20 kW with a heating cycle of approximately 0.5 seconds provides a case depth of approximately 0.024 inches (0.61 mm) and a hardness of "58" on the Rockwell C scale in cast iron seat inserts. Prior techniques which typically employ the same frequency at a power of approximately 7 kw with a heating cycle of approximately 7-8 seconds provides a case depth of between 0.050-0.060 inches (1.27-1.52 mm) and a hardness of "58" on the Rockwell C scale. Such parameters, while acceptable for gray cast iron engine components having integral cast iron valve seats simply will not provide suitable results in the environment of cast aluminum engine components utilizing ferrous seat ring inserts.
Claims (10)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT82302088T ATE17814T1 (en) | 1981-05-04 | 1982-04-23 | METHOD OF INDUCTION HEATING VALVE SEAT INSERTS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US25985681A | 1981-05-04 | 1981-05-04 | |
US259856 | 1988-10-19 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0064367A2 EP0064367A2 (en) | 1982-11-10 |
EP0064367A3 EP0064367A3 (en) | 1983-03-30 |
EP0064367B1 true EP0064367B1 (en) | 1986-01-29 |
Family
ID=22986708
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82302088A Expired EP0064367B1 (en) | 1981-05-04 | 1982-04-23 | Method for inductively heating valve seat inserts |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0064367B1 (en) |
JP (1) | JPS6047884B2 (en) |
AT (1) | ATE17814T1 (en) |
CA (1) | CA1187142A (en) |
DE (1) | DE3268757D1 (en) |
MX (1) | MX151639A (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3373317B2 (en) * | 1995-02-16 | 2003-02-04 | ヤマハ発動機株式会社 | Valve seat structure of cylinder head |
DE69606205T2 (en) * | 1995-02-28 | 2000-06-08 | Yamaha Motor Co Ltd | Cylinder head and method for manufacturing a valve seat |
JP3380081B2 (en) * | 1995-03-13 | 2003-02-24 | ヤマハ発動機株式会社 | Valve seat |
JPH0979014A (en) * | 1995-09-14 | 1997-03-25 | Yamaha Motor Co Ltd | Manufacture of cylinder head for engine |
US5778531A (en) * | 1995-09-14 | 1998-07-14 | Yamaha Hatsudoki Kabushiki Kaisha | Method of manufacturing cylinder head for engine |
US5745993A (en) * | 1996-02-27 | 1998-05-05 | Yamaha Hatsudoki Kabushiki Kaisha | Valve seat |
US10774939B2 (en) * | 2018-04-12 | 2020-09-15 | Cla-Val Co. | Valve with integral insert-cast seat and related method |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1035179B (en) * | 1955-05-20 | 1958-07-31 | Saviem | Process for the heat treatment of valve seats |
US3837934A (en) * | 1971-06-09 | 1974-09-24 | Park Ohio Industries Inc | Method for inductively heating valve seats |
USRE29046E (en) * | 1971-06-09 | 1976-11-23 | Park-Ohio Industries, Inc. | Method and apparatus for inductively heating valve seats |
EP0041317B1 (en) * | 1980-05-08 | 1986-08-27 | Park-Ohio Industries, Inc. | Method and apparatus for inductively heating valve seat inserts for hardening the seat surfaces |
-
1982
- 1982-04-23 DE DE8282302088T patent/DE3268757D1/en not_active Expired
- 1982-04-23 AT AT82302088T patent/ATE17814T1/en not_active IP Right Cessation
- 1982-04-23 EP EP82302088A patent/EP0064367B1/en not_active Expired
- 1982-05-03 MX MX192538A patent/MX151639A/en unknown
- 1982-05-03 CA CA000402185A patent/CA1187142A/en not_active Expired
- 1982-05-04 JP JP57075062A patent/JPS6047884B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
CA1187142A (en) | 1985-05-14 |
EP0064367A3 (en) | 1983-03-30 |
ATE17814T1 (en) | 1986-02-15 |
MX151639A (en) | 1985-01-23 |
DE3268757D1 (en) | 1986-03-13 |
EP0064367A2 (en) | 1982-11-10 |
JPS6047884B2 (en) | 1985-10-24 |
JPS57194212A (en) | 1982-11-29 |
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