Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
  • B23K31/02—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to soldering or welding
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H53/00—Cams or cam-followers, e.g. rollers for gearing mechanisms
  • F16H53/02—Single-track cams for single-revolution cycles; Camshafts with such cams
  • F16H53/025—Single-track cams for single-revolution cycles; Camshafts with such cams characterised by their construction, e.g. assembling or manufacturing features
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49293—Camshaft making
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T74/00—Machine element or mechanism
  • Y10T74/21—Elements
  • Y10T74/2101—Cams

Definitions

• the present invention relates to a built-up camshaft with a plurality of cams fastened to a shaft by at least one weld in each case, the shaft consisting of a first, carbonized steel and the cams having a hardened or hardenable rocker arm run-off surface made of a carbonized steel.
• the invention also relates to production methods for such a camshaft and the cams required for this.
• the object of the present invention is to specify how a welded joint which meets the permanent loads in practice can be achieved in a cost-effective manner in the case of a built-up camshaft of the type mentioned at the outset.
• the solution according to the invention therefore consists in the use of cams which are composed of at least two different materials and for which a second carburized steel, which can be easily welded with the steel of the time, is used in at least one area affected by the welding.
• the different materials of the cams can be connected to one another by soldering, plating, positive locking, positive locking, positive locking, adhesive, riveting and / or welding, but in particular resistance-pressing and / or friction welding. In the case of resistance pressure and / or friction welding, in particular the formation of micro and / or macro cracks can be avoided under the pressure applied.
• the cams have a core comprising the rocker arm drain surface and consisting of the high-carbon steel, which is arranged in the axial direction between at least two ring-shaped and / or ring-section-shaped elements made of the second carburized steel and welded to the shaft.
• the cams could have a shaft welded to the shaft made of the second carburized steel, which is arranged in the axial direction between two annular elements comprising the rocker arm run-out surface and made of the carbonized steel.
• the cams could also be constructed with at least two shells and have an outer shell made of the high-carbon steel comprising the rocker arm drain surface and at least one inner shell made of the second carbonized steel welded to the shaft.
• the part or parts of the cams made of the second, carburized steel are preferably welded to the shaft all the way round. In this way a high stability of the cams is achieved.
• the parts of the cams forming or encompassing the rocker arm run-off surfaces can be produced from curved profile strips, the profile strip or profiles preferably projecting from the shaft in the area of the cam tip in order to save weight and material.
• Abutting ends of the profile strip (s) can in this case be welded to one another, in particular by resistance pressure welding.
• the abutting ends were only connected to one another via the part or parts of the cams made of the second, carbonized steel. It can be particularly advantageous here if the abutting ends are designed to overlap one another in the circumferential direction.
• the parts of the cams forming or encompassing the rocker arm drain surfaces can also be formed in one piece and the shaft e.g. wrap completely flush.
• the attachment of the weld for fastening the cams to the shaft can be facilitated by the fact that in at least one of the areas affected by the weld in the part or parts made of the second carbonized steel adjacent to the A foot ring is provided and the welding is carried out through this foot ring.
• the first carburized steel used for the shaft and / or the second carburized steel used for the cams should have a carbon content of less than 0.5%.
• the high-carbon steel used for the rocker arm run-off surface of the cams in order to be good and sufficiently hardenable, can have a carbon content of more than 0.5%, but in particular of more than 0.75%.
• the rocker arm run-off surfaces of the cams are already hardened to their so-called hardness (for example to 64 HR C ++) and additionally tempered, if necessary. This advantageously avoids thermal stress on the entire camshaft, which could lead to shaft distortion.
• the welding can thereby be carried out at ambient temperature of the parts to be welded together. It is not necessary to preheat the shafts to avoid excessive thermal stress. It is also not necessary to subsequently heat the joined camshafts to reduce an excessively high weld seam hardness, as a result of which a change in the hardness of the previously hardened rocker arm runout surfaces of the cams is ultimately avoided.
• the welding of the cams can be carried out reliably in the manner described. The quality of the weld does not have to be checked continuously.
• the welding for fastening the cams to the shaft is carried out by laser technology. Because of the good weldability of the material of the cams made of the second carburized steel with the carburized steel of the shaft, the welding for fastening the cams on the shaft according to the method of claim 18 with a welding speed of greater than 2 m / s, but in particular of greater than 4 m / s. As a result, high production speeds can be achieved and the installations, which are expensive when using laser welding devices, can be optimally used.
• the cams are pre-fixed on the shaft before they are welded to the shaft in that their elements to be welded to the shaft are caulked with the shaft from the second carburized steel. This can e.g. by simply pressing the pliers and facilitating the subsequent welding, in which the cams do not have to be held on the shaft and the shaft with the pre-fixed cams can be rotated under a fixed welding beam.
• a general advantage of the invention can be seen in the fact that the cam material is practically freely selectable, regardless of the welding connection technology between the cam and the shaft.
• Fig. 1 under a) a first embodiment of a cam according to the invention in a
• FIG. 2 shows under a) in a longitudinal section a longitudinal section of a camshaft according to the invention with a cam according to FIG. 1 and under b) a cross section (BB) through this camshaft; 3 in a kind of enlarged detail from FIG. 2a) a special embodiment of a cam according to the invention with a welding foot;
• FIG. 5 shows a closed hollow cam under a) in view and under b) in section (C-C);
• the cam 1 of Fig. 1 has a rocker arm drain surface 2 and made of a high-carbon steel core 3, which is arranged in the axial direction between two annular elements 4 made of a carbonized steel. When viewed over its circumference, the core has an essentially uniform thickness ⁇ corresponding to the width b of the annular elements 4.
• a cam elevation or cam tip 5 is formed by the core 3.
• the core 3 is hardened along the rocker arm run-off surface 2.
• the corresponding surface hardness zone is designated 6.
• the core 3 and the two annular elements 4 are connected to one another by a resistance welding 7 carried out by pressing the parts against one another.
• This type of connection technology enables the two different steels to be welded together without pores or cracks.
• Fig. 2 shows the cam 1 of Fig. 1 with its through opening 8 pushed onto a shaft 9 made of a carbonized steel and welded to the shaft 9 to form a camshaft 10, the welding 11 in each case over 360 ° along the seam between the two circular elements 4 and the shaft 9 is in particular designed by laser welding.
• both the shaft 9 and the two annular elements 4 consist of a carbonized steel, they are good and weldable together without pores and cracks even at ambient temperature of the parts.
• FIG. 3 shows, in a kind of enlarged detail from FIG. 2a), a special embodiment of the two circular elements 4, each of which is provided with an annular groove 13.
• the annular groove 13 creates a type of welding foot 14 through which the welding 11 is carried out in the right part of FIG. 3.
• the presence of the welding foot 14 results in an advantageously wide welding cross section between the ring-shaped elements 4 and the shaft 9, which is very stable and highly resilient.
• the weld 11 is omitted in order to make the weld foot 14 more visible.
• the core 3 has a uniform thickness ⁇ over its circumference, which results in a distance or a cavity 12 between the core 3 and the shaft 9 in the area of the cam tip 5.
• Fig. 4 shows under a) the core 3 again in this training.
• the core is produced from a profile strip by bending. . '4 example showing, however, the core 3 could just as well in the area of the cam tip also have a greater thickness, so as shown in FIG under b) where the through hole is circular cylindrical 8 and a cavity 12 is avoided altogether.
• FIG under b where the through hole is circular cylindrical 8 and a cavity 12 is avoided altogether.
• FIG. 4 b) has a higher flexural rigidity in the region of the cam tip 5 than that of FIG. 4 a).
• the embodiment of FIG. 4 a) is characterized by a lower cam weight, by a lower material consumption, by a lower unbalance when rotating and by an easier manufacture.
• Fig. 4 c) shows a transition form between the embodiments of Fig. 4 a) and 4 b).
• the core 3 is provided in the transition area to a cavity 12 with thickenings 15, which are on the shaft surface nestle and have a certain stiffening effect for the cam tip 5.
• a comparable stiffening of the cam tip 5, on the other hand also brings about the two annular elements 4, since these are in full contact with the shaft. Possibly. this additional stiffening effect by the annular elements 4 is already sufficient to be able to carry out the core 3 according to FIG. 4 a) in practice.
• a measure which further increases the rigidity of the cam tip 5 could also consist in designing the ring-shaped elements 4 instead of circular in terms of their shape corresponding to the cross-sectional shape of the solid core of FIG. 4 b) and closing them all around with a core 3 according to FIG. 4 a) connect and as shown in Fig. 5 under a) and b).
• the cam tip 5 would then also be supported on the shaft via the two elements 4 formed in this way, which can be easily produced by stamping technology, and would additionally be stabilized against transverse forces.
• the core of the cams 1 described above can be produced in a simple manner by bending from one, but also from several profile strips, which e.g. be cut to length from a longer strip.
• Fig. 6 shows under a) a simple profile strip 20 and under b) the core 21 for a cam 1, as it is created by bending the two ends of the profile strip 20 together. The two ends can subsequently be connected to one another and the core 21 can thereby be closed. Resistance pressure welding is particularly suitable for this. Any welding bead that arises in the process would have to be removed subsequently.
• FIG. 6 shows a profile strip 22 of non-uniform thickness, from which the cam core 23 shown under d) can be produced by bending its ends and which corresponds to that of FIG. 4 c).
• FIG. 6 shows a cam core 24, which is composed of two profile strips, each bent into half-shells 25, 26.
• the two joints of the two half-shells 25, 26 can again be welded together.
• This embodiment has the advantage that the profile strips do not have to be bent as much and the material is therefore less exposed to loads.
• 6 shows how a solid core 29 according to FIG. 4 b) can be produced from two half-shells 27, 28, for example.
• the butt joints could also be arranged at another point along the circumference of the cam, in particular offset by 180 ° or 90 °, as can also be seen from the comparison of FIGS. 6 e) and 6 f).
• a core 30 made of a high-carbon steel is flanked by a ring of carbonized steel by two ring elements 31 arranged on both sides of it, positively as well as, for example, resistance-welded, cross-sectionally C-shaped in cross section.
• the width b of two annular elements 33 made of a low-carbon steel arranged on both sides of a core 32 made of a high-carbon steel is chosen to be smaller than the thickness ⁇ of the core 32, so that the core 32 radially outwards over the elements 33 survives.
• the relationships with respect to the widths b) and thickness ⁇ are reversed.
• annular elements 36 corresponding to FIG. 7 b) are embedded in lateral grooves of a core 37 or the core 37 is pulled outwards on both sides over the annular elements 36 up to their end faces.
• FIG. 7 f) there is only a single, ring-shaped element 39 made of a carbonized steel, which is arranged completely below a core 40 made of a carbonized steel. This gives the cam a double-shell structure.
• FIG. 7 d annular elements 36 corresponding to FIG. 7 b) are embedded in lateral grooves of a core 37 or the core 37 is pulled outwards on both sides over the annular elements 36 up to their end faces.
• the annular elements 38 are triangular in cross section.
• FIG. 7 f) there is only a single, ring-shaped element 39 made of a carbonized steel, which is arranged completely below a core 40 made of a carbonized steel.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Butt Welding And Welding Of Specific Article (AREA)
• Gears, Cams (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4555969

Family Applications (1)

Country Status (7)

Cited By (3)

Families Citing this family (5)

Citations (4)

Family Cites Families (6)

• 2002
  • 2002-06-13 AT AT02737708T patent/ATE497855T1/de active
  • 2002-06-13 US US10/480,572 patent/US20040237706A1/en not_active Abandoned
  • 2002-06-13 WO PCT/CH2002/000319 patent/WO2002100588A1/de not_active Ceased
  • 2002-06-13 EP EP02737708A patent/EP1395386B1/de not_active Expired - Lifetime
  • 2002-06-13 DE DE50214904T patent/DE50214904D1/de not_active Expired - Lifetime
  • 2002-06-13 ES ES02737708T patent/ES2362207T3/es not_active Expired - Lifetime
  • 2002-06-13 JP JP2003503393A patent/JP4051335B2/ja not_active Expired - Lifetime

Patent Citations (4)

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