CA1327461C - Process for producing individual cams from cast material - Google Patents
Process for producing individual cams from cast materialInfo
- Publication number
- CA1327461C CA1327461C CA000610825A CA610825A CA1327461C CA 1327461 C CA1327461 C CA 1327461C CA 000610825 A CA000610825 A CA 000610825A CA 610825 A CA610825 A CA 610825A CA 1327461 C CA1327461 C CA 1327461C
- Authority
- CA
- Canada
- Prior art keywords
- bar
- process according
- surface layer
- cams
- cam
- 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 - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D9/00—Machines or plants for casting ingots
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
- B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P13/00—Making metal objects by operations essentially involving machining but not covered by a single other subclass
- B23P13/04—Making metal objects by operations essentially involving machining but not covered by a single other subclass involving slicing of profiled material
-
- 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
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—Camshafts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P2700/00—Indexing scheme relating to the articles being treated, e.g. manufactured, repaired, assembled, connected or other operations covered in the subgroups
- B23P2700/02—Camshafts
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
- Gears, Cams (AREA)
- Powder Metallurgy (AREA)
- Heat Treatment Of Articles (AREA)
- Forging (AREA)
Abstract
Abstract A process for producing individual cams of cast material for assembled camshafts, in which a bar having the cross-section of a cam is produced by continuous casting and individual cams are separated from the solidified bar.
The process produces cams with good tribological characteristics at relatively low cost.
The process produces cams with good tribological characteristics at relatively low cost.
Description
The invention relates to a process for producing individual cams from cast material for assembled camshafts.
Assembled camshafts for which it is possible to use tubes for the basic shaft member are advantageous from the point of view of weight. Independently of the fixing method, e.g. shrinking, hydraulic deformation of the tube or other methods, steel cams used for the above purpose do not cause any problems regarding the connection, but as a rule, their tribological values are not the most favourable for certain cam followers, independently of the material of the bucket tappets or rocker arms. On the other hand, cast cams are well suited in respect of their running characteristics, especially if they are provided with a hard, wear-resistant surface layer, but because of the risk of crack formation they cause problems when producing the connection. In particuar, the latter applies to cams made of chilled cast iron with a ledeburitic surface layer which is too brittle for hydraulic expansion so that the cams burst open during plastic deformation.
Cams made of malleable cast iron with a ledeburitic surface layer produced by remelting hardening are more suitable, but the process involved is too complicated and expensive so that the production costs of the individual cams are too high.
Cast cams with an elongatable structure such as malleable cast iron or cast spheroidal graphite subjected to induction surface hardening, which is acceptable from a cost point of view, after hardening only have a martensitic surface whose tribological properties do not meet all necessary requirements as compared to the desired ledeburitic surface.
It is an object of the present invention to provide a process for producing individual cams of a cast material " ` ~ ' `' ' .
Assembled camshafts for which it is possible to use tubes for the basic shaft member are advantageous from the point of view of weight. Independently of the fixing method, e.g. shrinking, hydraulic deformation of the tube or other methods, steel cams used for the above purpose do not cause any problems regarding the connection, but as a rule, their tribological values are not the most favourable for certain cam followers, independently of the material of the bucket tappets or rocker arms. On the other hand, cast cams are well suited in respect of their running characteristics, especially if they are provided with a hard, wear-resistant surface layer, but because of the risk of crack formation they cause problems when producing the connection. In particuar, the latter applies to cams made of chilled cast iron with a ledeburitic surface layer which is too brittle for hydraulic expansion so that the cams burst open during plastic deformation.
Cams made of malleable cast iron with a ledeburitic surface layer produced by remelting hardening are more suitable, but the process involved is too complicated and expensive so that the production costs of the individual cams are too high.
Cast cams with an elongatable structure such as malleable cast iron or cast spheroidal graphite subjected to induction surface hardening, which is acceptable from a cost point of view, after hardening only have a martensitic surface whose tribological properties do not meet all necessary requirements as compared to the desired ledeburitic surface.
It is an object of the present invention to provide a process for producing individual cams of a cast material " ` ~ ' `' ' .
which is cost-effective as compared to prior art processPs and supplies parts with good tribological properties. In the present invention, a bar having the cross-section of a cam is produced by continuous casting, preferably with a slight grinding allowance as compared with the finished cam, and individual cams, preferably with the finished dimension relative to the width of the cam, are separated from the solidified bar.
Such a process requires relatively low investment costs and is capable of producing individual cams of uniform quality at a high production speed and favourable costs.
The continuous casting process is known in itself and is carried out with production facilities employing a mould mouth piece corresponding to the profile of the finished cam, taking into account a slight grinding allowance.
Typically the cross-section has a smoothly continuously varying radial dimension around at least part of and preferably all of the circumference of the cam. The temperature of the mould mouth piece, whose design is similar to that of a cooled die, is such that a ledeburitic surface layer is produced. The resulting bars to be cut to the required lengths subsequently only have to be separated into individual cams in widths as required, and ground after having been joined to the camshaft.
Separation is usually effected by a fusion cutting process generating high temperatures at extremely high cutting speeds, with no special requirements having to be met by the material quality.
An axial aperture may be formed in the individual separated cams by drilling or broaching. Alternatively, the axial aperture may be produced in the bar during the continuous casting process.
In a preferred form, the bar, after emerging from the mould mouth piece where the cast material is cooled to -- 3 - ~3274~1 such an extent that a doughy outer skin is formed on the bar, is guided through a powder packing substance consisting of alloying elements which, together with the cast material, produces an alloyed layer on the surface.
The alloying materials in this case are preferably the carbide forming agents manganese, chromium, silicon, tungsten, vanadium, molybdenum, titanium, nickel, tantalum, niobium and carbon.
Adjoining the container for the powder packing substance there may be provided a further mould piece which is heated in such a way that the powder adhering to thz bar is fused on to the surface to form an alloy.
Instead of arranging a heated mould piece it is also possible to provide a drawing ring and/or a roller assembly in which, during subsequent compression, a layer is sintered on to the surface and compressed.
The cast spheroidal graphite of the base material as well as the ledeburitic surface layer of the bar is produced by adding conventional admixtures to the liquid metal, by the so-called inoculation process.
For the purpose of producing a connection based on the hydraulic expansion principle, it is particuarly advantageous to use individual cams produced in accordance with the invention whose base material has a yield point >500 N/mm2 and an elongation at rupture of _ 2%. Further advantageous features consist in the surface layer having a hardness of _ 48 HRC and a thickness of 0.5 to 2 mm and that the transition region between the elongatable basic structure of cast spheroidal graphite and the hard ledeburitic surface layer is limited to a narrow region of _ 0.5 mm thickness. The cams are preferably produced from bars which relative to the finished cams have only a "` , . ' ,: ' ~ ' .
.
1327~
slight grinding allowance of _ 0.5 mm. In this way, machining operations are reduced to a minimum. The alloyed-on running layer comprising a high content of hard mixed carbides provides the cams with a very high wear resistance which does not adversely affect the deformability of the base material for the purpose of hydraulic attachment to the expanded tube. The consumption of alloying elements which may also be added in the form of powder mixtures is extremely low so that considerable price advantages are achieved as compared to through-alloyed cams, without the strength and elongatability of the base material being adversely affected in the sense of resulting in embrittlement. The said process stages of a layer being thermally sintered on and alloyed on under mechanical pressure may be combined in a suitable way, with the operation of re-compression of the hot surface also having a positive effect. The process in accordance with the,invention can be carried out at reasonable cost. The individual cams in accordance with the invention are characterised by improved proprties as compared to prior art ca=s made of a cast oaterial.
. ~
. .
. - ~ , , . - . -. .
Such a process requires relatively low investment costs and is capable of producing individual cams of uniform quality at a high production speed and favourable costs.
The continuous casting process is known in itself and is carried out with production facilities employing a mould mouth piece corresponding to the profile of the finished cam, taking into account a slight grinding allowance.
Typically the cross-section has a smoothly continuously varying radial dimension around at least part of and preferably all of the circumference of the cam. The temperature of the mould mouth piece, whose design is similar to that of a cooled die, is such that a ledeburitic surface layer is produced. The resulting bars to be cut to the required lengths subsequently only have to be separated into individual cams in widths as required, and ground after having been joined to the camshaft.
Separation is usually effected by a fusion cutting process generating high temperatures at extremely high cutting speeds, with no special requirements having to be met by the material quality.
An axial aperture may be formed in the individual separated cams by drilling or broaching. Alternatively, the axial aperture may be produced in the bar during the continuous casting process.
In a preferred form, the bar, after emerging from the mould mouth piece where the cast material is cooled to -- 3 - ~3274~1 such an extent that a doughy outer skin is formed on the bar, is guided through a powder packing substance consisting of alloying elements which, together with the cast material, produces an alloyed layer on the surface.
The alloying materials in this case are preferably the carbide forming agents manganese, chromium, silicon, tungsten, vanadium, molybdenum, titanium, nickel, tantalum, niobium and carbon.
Adjoining the container for the powder packing substance there may be provided a further mould piece which is heated in such a way that the powder adhering to thz bar is fused on to the surface to form an alloy.
Instead of arranging a heated mould piece it is also possible to provide a drawing ring and/or a roller assembly in which, during subsequent compression, a layer is sintered on to the surface and compressed.
The cast spheroidal graphite of the base material as well as the ledeburitic surface layer of the bar is produced by adding conventional admixtures to the liquid metal, by the so-called inoculation process.
For the purpose of producing a connection based on the hydraulic expansion principle, it is particuarly advantageous to use individual cams produced in accordance with the invention whose base material has a yield point >500 N/mm2 and an elongation at rupture of _ 2%. Further advantageous features consist in the surface layer having a hardness of _ 48 HRC and a thickness of 0.5 to 2 mm and that the transition region between the elongatable basic structure of cast spheroidal graphite and the hard ledeburitic surface layer is limited to a narrow region of _ 0.5 mm thickness. The cams are preferably produced from bars which relative to the finished cams have only a "` , . ' ,: ' ~ ' .
.
1327~
slight grinding allowance of _ 0.5 mm. In this way, machining operations are reduced to a minimum. The alloyed-on running layer comprising a high content of hard mixed carbides provides the cams with a very high wear resistance which does not adversely affect the deformability of the base material for the purpose of hydraulic attachment to the expanded tube. The consumption of alloying elements which may also be added in the form of powder mixtures is extremely low so that considerable price advantages are achieved as compared to through-alloyed cams, without the strength and elongatability of the base material being adversely affected in the sense of resulting in embrittlement. The said process stages of a layer being thermally sintered on and alloyed on under mechanical pressure may be combined in a suitable way, with the operation of re-compression of the hot surface also having a positive effect. The process in accordance with the,invention can be carried out at reasonable cost. The individual cams in accordance with the invention are characterised by improved proprties as compared to prior art ca=s made of a cast oaterial.
. ~
. .
. - ~ , , . - . -. .
Claims (11)
1. A process for producing individual eccentric cams from cast material for assembled camshafts, comprising the steps of: continuously casting a ferrous alloy to form a bar having a cross-section of a cam; controlling the composition of the alloy, the casting temperature and the cooling of the bar to provide the bar with a core of spheroidal graphite cast iron and a hard surface layer of chilled cast iron with a ledeburitic structure; and separating individual cams from the bar when it is solidified.
2. A process according to claim 1, wherein the controlling step includes controlling the composition of said ferrous alloy and the continuous casting process parameters 80 that said core is a material with a yield point of at least 500 N/mm2 and an elongation at rupture of at least 12%.
3. A process according to claim 1, wherein the controlling step includes controlling the composition of said ferrous alloy and the continuous casting parameters 80 that said surface layer of said chilled cast iron has a hardness of at least 48 HRC.
4. A process according to claim 3, wherein said surface layer has a thickness of between 1.5 and 5mm, and preferably between 2.5 and 3mm.
5. A process according to claim 1, wherein the controlling step includes controlling the continuous casting process parameters so that a transition region is provided between said hard surface layer and said core.
6. A process according to claim 5, wherein said transition region has a thickness of between 2 and 5mm.
7. A process according to claim 1, wherein said casting step includes producing the bar with a grinding allowance of about 0.5 mm thickness relative to a finished cam.
8. A process according to claim 1, wherein said separating step includes separating the bar into lengths from which a plurality of cams may be produced and then cutting the individual cams from said lengths to a finish cam width dimension.
9. A process according to claim 1, wherein the cam cross-section has a point and a rounded back and wherein the bar is continuously cast horizontally with the point of the cam directed downwardly.
10. A process according to claim 1, wherein said continuous casting includes entering the bar into a molding assembly in which said core and hard surface layer are formed, then, while said surface layer is in doughy condition, moving the bar through powdered alloying elements and subsequently moving the bar through a heated die to sinter the powdered alloying elements to form an alloy with the hard surface layer.
11. A process according to claim 10, further comprising the step of pressing the sintered-on alloying elements by rolling.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3836328A DE3836328A1 (en) | 1988-10-25 | 1988-10-25 | METHOD FOR PRODUCING SINGLE CAMS FROM CAST MATERIAL |
| DEP3836328.3-24 | 1988-10-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1327461C true CA1327461C (en) | 1994-03-08 |
Family
ID=6365880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000610825A Expired - Fee Related CA1327461C (en) | 1988-10-25 | 1989-09-08 | Process for producing individual cams from cast material |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0365757B1 (en) |
| JP (1) | JP2557711B2 (en) |
| KR (1) | KR920004451B1 (en) |
| BR (1) | BR8904644A (en) |
| CA (1) | CA1327461C (en) |
| DE (2) | DE3836328A1 (en) |
| ES (1) | ES2038377T3 (en) |
| MX (1) | MX172720B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4029026A1 (en) * | 1990-08-25 | 1992-03-05 | Wizemann Gmbh U Co J | SHAFT FOR INTERNAL COMBUSTION ENGINES |
| DE4205801C1 (en) * | 1992-02-26 | 1993-07-15 | Aeg-Elotherm Gmbh, 5630 Remscheid, De | |
| DE4420092C3 (en) * | 1994-06-09 | 2001-08-09 | Daimler Chrysler Ag | Process for manufacturing a built camshaft with induction hardened cams |
| US6006429A (en) * | 1994-06-09 | 1999-12-28 | Daimlerchrysler Ag | Method of inductively hardening the cams of a camshaft |
| EP0951371B1 (en) | 1997-01-08 | 2001-08-08 | Paul Wurth S.A. | Method of producing a cooling plate for iron and steel-making furnaces |
| DE10055449A1 (en) * | 2000-11-09 | 2002-05-23 | Schwaebische Huettenwerke Gmbh | Gradient material molded body |
| JP4947847B2 (en) * | 2001-04-05 | 2012-06-06 | ダイヤテックス株式会社 | Reinforced embankment sheet |
| DE102013202657A1 (en) * | 2012-12-20 | 2014-07-10 | Mahle International Gmbh | Method for thermal joining of non-circular functional components on a shaft |
| DE102013210258A1 (en) * | 2013-06-03 | 2014-12-04 | Mahle International Gmbh | Method of making a cam |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1758466C3 (en) * | 1968-06-07 | 1975-11-13 | Mannesmann Ag, 4000 Duesseldorf | Process for the continuous casting of hollow strands |
| US3841390A (en) * | 1973-01-29 | 1974-10-15 | F Dibenedetto | Continuous molding machine |
| JPS6021119A (en) * | 1983-07-13 | 1985-02-02 | Mitsubishi Electric Corp | Production of gear |
| JPS60152665A (en) * | 1984-01-19 | 1985-08-10 | Riken Corp | Cam piece and its production |
| DE8525769U1 (en) * | 1985-09-10 | 1985-10-17 | J. Wizemann Gmbh U. Co, 7000 Stuttgart | camshaft |
| JPS62134160A (en) * | 1985-12-05 | 1987-06-17 | Honda Motor Co Ltd | Production of cam shaft |
| GB2187405A (en) * | 1986-03-05 | 1987-09-09 | Gkn Technology Ltd | Securing elements on tubular members |
-
1988
- 1988-10-25 DE DE3836328A patent/DE3836328A1/en active Granted
-
1989
- 1989-07-14 ES ES198989112935T patent/ES2038377T3/en not_active Expired - Lifetime
- 1989-07-14 EP EP89112935A patent/EP0365757B1/en not_active Expired - Lifetime
- 1989-07-14 DE DE8989112935T patent/DE58903603D1/en not_active Expired - Fee Related
- 1989-08-23 JP JP1215135A patent/JP2557711B2/en not_active Expired - Lifetime
- 1989-09-08 CA CA000610825A patent/CA1327461C/en not_active Expired - Fee Related
- 1989-09-15 BR BR898904644A patent/BR8904644A/en not_active IP Right Cessation
- 1989-09-27 MX MX017722A patent/MX172720B/en unknown
- 1989-10-24 KR KR1019890015269A patent/KR920004451B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| MX172720B (en) | 1994-01-10 |
| ES2038377T3 (en) | 1993-07-16 |
| EP0365757B1 (en) | 1993-02-24 |
| JPH02129451A (en) | 1990-05-17 |
| DE3836328C2 (en) | 1990-10-18 |
| EP0365757A3 (en) | 1990-10-10 |
| EP0365757A2 (en) | 1990-05-02 |
| DE58903603D1 (en) | 1993-04-01 |
| KR920004451B1 (en) | 1992-06-05 |
| JP2557711B2 (en) | 1996-11-27 |
| KR900006044A (en) | 1990-05-07 |
| BR8904644A (en) | 1990-04-24 |
| DE3836328A1 (en) | 1990-04-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |