Method for producing roller tappet, forming tool and roller tappet

Abstract

The invention relates to a method for producing a roller tappet (44) for a pump or valve train of an internal combustion engine, comprising a cylindrical housing (43) for guiding a longitudinal movement of the roller tappet (44) in a bore of the internal combustion engine, the cylindrical blank (1) of the housing (43) being produced in a lightweight design and having at least one flattened section (5, 6, 7, 8) on the outer diameter, at least one edge (11 to 18) formed on the outer diameter of the blank (1) in an intermediate region between the axial ends of the blank (1) is subjected to a low-notching deburring treatment by turning. The invention also relates to a forming tool (31, 34, 36) for producing a roller tappet (44) in such a method. The invention also relates to a roller tappet (44) having a lightweight structure produced by such a method.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a roller tappet for a pump mechanism or valve mechanism of an internal combustion engine. The present invention also relates to a forming die for manufacturing the roller tappet using this method. The present invention also relates to a roller tappet manufactured using this method. Background Art

[0002] DE 10 2017 107 100 B3 discloses a multi-part roller tappet for a high-pressure fuel pump, which is guided in a housing receptacle in the direction of its longitudinal axis and is movable in the longitudinal direction by a cam drive of a camshaft. Summary of the Invention

[0003] It is therefore the object of the present invention to provide a method, a forming tool, and a roller tappet of the aforementioned type, which enable simple and cost-effective production and ensure reliable and efficient operation of the internal combustion engine.

[0004] This object is achieved by the features of claim 1 and alternatively by the features of claim 8 or 10. Further advantageous and claimed embodiments are apparent from the corresponding dependent claims, the description and the drawings.

[0005] A method for producing a roller tappet for a pump mechanism or valve train of an internal combustion engine is proposed, the roller tappet having a housing for guiding the movement of the roller tappet in a bore of the internal combustion engine. Provision is made for the housing to be produced as a cylindrical blank in a lightweight construction, for at least one flattened portion to be provided on the outer diameter of the blank, and for at least one edge formed on the outer diameter of the blank in an intermediate region between the axial ends of the blank to be deburred with low notch effect by turning.

[0006] Thus, a roller tappet with a reduced-mass housing can be manufactured in a simple, lightweight construction, thereby increasing dynamics and efficiency during operation. Sharp edges on the outer diameter of the housing produced in the aforementioned intermediate region during housing machining can be quickly and simply deburred with minimal notch effect by turning, resulting in no sharp edges on the outer diameter of the housing in the unflattened region that could impair housing strength.

[0007] Therefore, during operation, it is possible to reliably avoid scraping of the material in the hole for guiding the tappet by sharp edges on the housing due to the occurring lateral forces and the resulting operational faults, in particular operational faults due to chips being pushed into the hole, and ensure low-friction, efficient and reliable operation.

[0008] For low-notch deburring, a slightly concavely curved radius is preferably produced by turning on one or more edges. This arcuate shape ensures a low-notch embodiment at the outer diameter of the housing, particularly in its unflattened areas, for example by forming a groove with a circular cross-sectional profile and a shallow cut-in depth at the outer diameter of the housing. Low-notch deburring shapes with a continuous course and no abrupt changes in direction are also conceivable, such as arcs, particularly arcs or ellipses. In this way, one or more edges can be deburred by turning without weakening the component strength in the unflattened areas of the blank.

[0009] In a particularly preferred embodiment of the invention, one or more flattened portions are produced that are rectangular in radial plan view and each have two edges perpendicular to the cylindrical axis of the blank, i.e., in the circumferential direction of the blank, and two edges parallel to the cylindrical axis at the outer diameter of the blank. This allows the production of two edges parallel to the longitudinal axis of the blank, i.e., in the direction of movement of the roller tappet during operation, without the need for deburring these edges.

[0010] Preferably, flattened portions are produced with longer edges perpendicular to the cylindrical axis of the blank in a radial top view and shorter edges parallel to the cylindrical axis. This allows for simple deburring of the longer longitudinal edges by turning. Preferably, one or more flattened portions are each produced by milling.

[0011] In another preferred embodiment of the present invention, if the blank is manufactured with a plurality of flattened portions, the lightweight structure of the roller tappet can be further improved.

[0012] Preferably, the blank is manufactured with at least two flattened portions arranged in series in the axial direction and at least two flattened portions arranged in series in the circumferential direction. The edges extending in the circumferential direction formed by the production of the flattened portions at the outer diameter in the axial middle region are deburred in one operation by turning.

[0013] Preferably, the flattened portions are processed in a manner offset by 180° relative to one another in the circumferential direction. In this way, thin-walled blanks can be produced particularly cost-effectively by an extrusion process.

[0014] Preferably, the blank is formed into a hollow structure by an extrusion process, which has a receptacle for accommodating the cam roller that is in the form of an elongated hole in top view, starting from the axial end, so that the wall thickness on the longitudinal sides of the receptacle is greater than the wall thickness on the end sides of the receptacle. During the production of the blank, good extrusion processability is achieved by material accumulation in the areas of greater wall thickness.

[0015] In this case, the flattened portion is preferably provided in the outer diameter region of the blank, where the wall thickness is greater, so that the blank is produced with a thin-walled structure.

[0016] Preferably, two flattened portions are produced at the outer diameter, each starting from an axial end of the blank for receiving a cam roller in the receptacle.

[0017] The proposed method can also be used to produce cup tappets for pump mechanisms or valve trains of internal combustion engines. Roller tappets or cup tappets produced by the proposed method can be used particularly advantageously in passenger cars or trucks.

[0018] The object of the present invention is also achieved by a forming die for producing a roller tappet for a pump mechanism or valve train of an internal combustion engine using the aforementioned method. In this case, the forming die has a die cutting edge with a forming profile including at least one convex radius for deburring at least one edge produced by a flattened portion produced on the outer diameter of the blank by turning with minimal notch effect. This results in the advantages already mentioned.

[0019] Preferably, the die cutting edge has a profile with a plurality of convexly curved radii for simultaneously deburring a plurality of edges with a low notch effect by turning, thereby enabling a plurality of edges to be deburred with a low notch effect in one operation.

[0020] In another aspect of the present invention, a roller tappet for a pump mechanism or valve train of an internal combustion engine is proposed, which is produced in a lightweight manner using the aforementioned method. This results in the advantages already mentioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features of the invention claimed for protection are apparent from the following description and the accompanying drawings which further illustrate the invention.

[0022] Figure 1 A perspective view of a housing of a roller tappet for a pump mechanism of an internal combustion engine, produced as a blank using the method according to the invention, in a first production stage,

[0023] Figure 2 shows an axial top view of the blank taken at one axial end,

[0024] Figure 3 shows a longitudinal section of the blank,

[0025] Figure 4 shows a longitudinal section of the blank rotated 180° about the longitudinal axis,

[0026] Figure 5 shows a perspective view of the blank in a second manufacturing stage,

[0027] Figure 6 Shown Figure 5 An axial top view of the blank obtained at an axial end,

[0028] Figure 7 Shown Figure 5 A first embodiment in which a blank is engaged with a forming die for deburring according to the present invention,

[0029] Figure 8 Shown Figure 7 The longitudinal section of the blank after deburring,

[0030] Figure 9 Shown Figure 8 The enlarged part of

[0031] Figure 10 Shown Figure 8 The longitudinal section of the blank rotated 180° around the longitudinal axis,

[0032] Figure 11 and Figure 12 A partial perspective view of the blank is shown,

[0033] Figure 13 Shows the blank and Figure 7 A perspective view of a forming die joint for deburring according to the present invention,

[0034] Figure 14 A perspective view showing a second embodiment of a blank being engaged with a forming die for deburring according to the present invention,

[0035] Figure 15 A perspective view showing a third embodiment of a blank being engaged with a forming die for deburring according to the present invention,

[0036] Figure 16 a flow chart showing the sequence of stages of the method according to the invention,

[0037] Figure 17 shows a side view of a roller tappet according to the invention,

[0038] Figure 18 shows a side view of the roller tappet according to the invention rotated 180° about the longitudinal axis,

[0039] Figure 19 A perspective view of a roller tappet according to the invention is shown. DETAILED DESCRIPTION

[0040] The accompanying drawings show, by way of example, various manufacturing states of a roller tappet for a pump drive of an internal combustion engine manufactured using the method according to the invention. These schematic diagrams also show a forming die according to the invention and a roller tappet according to the invention.

[0041] Figures 1 to 4 The figure shows a blank 1 of a roller tappet housing to be finished, which is produced as an elongated cylindrical component by an extrusion process using the method according to the invention, in a first manufacturing stage. This housing serves to guide the roller tappet in longitudinal motion in a tappet guide (not shown) (in a stationary component of the internal combustion engine, this tappet guide is particularly a bore) along its imaginary cylinder axis or longitudinal axis 2. This cylinder axis or longitudinal axis 2 also serves as the center axis of the blank 1.

[0042] The blank 1 is provided, starting from the axial end on the drive side, with a receptacle 3 in the form of an elongated hole in the axial view, for arranging a cam roller (not shown) in the housing to be completed. The cam roller is used to receive the cam lift movement of the roller tappet from the camshaft (not shown) of the internal combustion engine. Figure 1 and Figure 2 ).

[0043] The blank 1 comprises a rod-shaped pump contact part 4 formed integrally therewith and arranged centrally in the radial interior, which pump contact part projects axially at the output-side end in order to transmit the cam lift movement, in particular to a high-pressure pump piston (not shown) in the pump drive. Figure 3 and Figure 4 ).

[0044] The oblong hole-shaped receptacle 3 has two parallel longitudinal sides and closes in an arcuate shape at the narrow end. In the blank 1, the wall thickness S on the opposite longitudinal sides of the oblong hole-shaped receptacle 3 is greater than the wall thickness s on the end sides of the receptacle 3. This creates a material accumulation on each of the longitudinal sides of the receptacle 3. This accumulation, in addition to the receptacle 3 for the cam roller, ensures good extrudability in the outer annular region.

[0045] exist Figures 5 to 8 In the second manufacturing stage shown, preferably four flattened portions 5, 6, 7, 8 are produced, preferably by milling, in the region of the outer diameter of the blank 1 with a greater wall thickness S in order to reduce the mass of the blank. These flattened portions are arranged in two rows, each row having two axially aligned flattened portions 5, 6 or 7, 8. In each row, the flattened portions are spaced axially apart from one another by a cylindrical intermediate region 27 or 28, respectively, which protrudes radially in the form of ribs in the axial direction between the flattened portions 5, 6 or 7, 8.

[0046] The two rows of flattened portions 5, 6 and / or 7, 8 are arranged radially opposite to each other at the outer diameter of the blank 1 in a circumferential direction, corresponding to the region of greater wall thickness S. Here, the flattened portions 5, 7 or 6, 8 are arranged aligned one after another in the circumferential direction. In this way, the blank 1 ( Figure 8 and Figure 10 ). In this case, a wall thickness of 1 to 1.5 mm can preferably be achieved.

[0047] The first flattened portion 5 or 7 of each row is machined starting from the drive-side axial end of the blank 1, which serves to accommodate the cam roller in the receptacle 3. Aligned through-holes 9, 10 are formed in the region of the first flattened portion 5 or 7 for accommodating a cam roller pin, on which the cam roller is rotatably mounted.

[0048] The flattened portions 5, 6, 7, and 8 each have a rectangular shape in a radial top view. At the outer diameter of the blank 1, the flattened portions each form two edges 11, 12 or 13, 14 and 15, 16 or 17, 18, extending perpendicularly to the cylinder axis 2 of the blank 1 in the circumferential direction, and two edges 19, 20 or 21, 22 and 23, 24 or 25, 26, extending parallel to the cylinder axis 2. The flattened portions 5, 6, 7, and 8 are aligned in the circumferential direction with their longer edges 11, 12 or 13, 14 and 15, 16 or 17, 18, and are aligned parallel to the cylinder axis 2 with their shorter edges 19, 20 or 21, 22 and 23, 24 or 25, 26.

[0049] During the production of the flattened portions 5, 6, 7, 8, burrs generated on the long edges 11, 12 or 13, 14 and 15, 16 or 17, 18 extending perpendicularly to the cylindrical axis 2 of the blank 1 (i.e., transversely to its direction of movement during operation) must be removed because these burrs can damage the guide bore for guiding the tappet due to material scraping during operation and can cause operational malfunctions due to chip accumulation. The long edges 11, 15 and 12, 16 and 13, 17 and 14, 18 arranged one after the other in the circumferential direction are all simply deburred simultaneously by turning.

[0050] During the production of the flattened portions 5 , 6 , 7 , 8 , the resulting shorter edges 19 , 20 or 21 , 22 and 23 , 24 or 25 , 26 each extend parallel to the direction of movement of the roller tappet during operation, so that they do not need to be deburred.

[0051] The edges 12, 13, 14 and 16, 17, 18 of the corresponding flattened portions 5, 6, 7, 8, which extend in the circumferential direction and are located in the central region of the blank 1 between the axial ends, must be deburred with a low notch effect in order to avoid weakening of the unflattened cylindrical region by notch stress concentrations during turning during deburring of the flattened regions. The edges 11 at the drive-side end and the edges at the output-side end of the blank 1 can be deburred in a simple manner (as shown by chamfering) since there is no risk of notch stress concentrations here.

[0052] according to Figures 7 to 9 For deburring, a slightly convex, preferably arc-shaped, rounded portion 29 is produced by turning on each of the edges 12 to 18. The slightly rounded shape ensures an embodiment with a low notch effect at the outer diameter, in particular at the unflattened area of ​​the blank 1, preferably in the form of a groove 30 shown by a dashed line, which has a slightly rounded cross-sectional profile and a small cutting depth at the outer diameter of the blank 1, as shown in FIG. Figures 10 to 15 Other shapes for deburring with a low cutting effect that have a continuous course and no sudden changes in direction are also conceivable, such as non-arcuate arches with a varying curvature, in particular ellipses.

[0053] Figure 7 and Figures 13 to 15 3 shows various embodiments of the engagement of forming tools 31 , 34 , 36 , each designed as a turning tool, with a blank 1 for deburring by turning with low notch effect.

[0054] Figure 7 and Figure 13 The forming tool 31 shown in the first embodiment has a tool cutting edge 32 with a profile contour for simultaneously deburring all edges 12, 13, 14 and 16, 17, 18 located in the center region in a single operation. For this purpose, the profile contour is configured with three convex portions 33 corresponding to the shapes of the recesses that need to be produced on the edges 12, 13, 14 and 16, 17, 18, respectively, for the purpose of deburring, with a low-cutting effect. In this way, the forming tool 31 forms a profile template tool that can deburr the six edges 12, 13, 14 and 16, 17, 18 extending in the circumferential direction, produced in the axial center region of the blank 1, with a low-cutting effect, in just one clamping operation.

[0055] In the second embodiment, Figure 14The forming tool 34 shown has a die cutting edge 35 having a profile with two convex radii 33, which corresponds to the shape of the recesses to be produced in the middle regions 27, 28 for low-notch deburring at the edges 12, 13 and 16, 17, respectively. With this double-blade forming tool 35, the four edges formed in the middle regions 27, 28 can be deburred with low notch effect in a single operation using a single clamping operation.

[0056] In accordance with Figure 15 In the third embodiment, a single-blade forming die 36 is shown, which has a die cutting edge 37 with a convex portion 33 for deburring. Therefore, the single-blade forming die 36 can be used to deburr one of the edges 12, 13, 14 and 16, 17, 18 with a low notch effect in a single use.

[0057] Figure 16 The sequence of stages during the manufacture of the roller tappet described above is schematically shown. In a first stage, the blank 1 of the housing to be manufactured of the roller tappet is preferably cold extruded ( Figures 1 to 4 ). Then, machining is performed on the blank 1. This includes, in particular, the production of flattened portions 5 to 8 by milling and the production of through-holes 9, 10 for receiving the cam roller pins by punching and turning, as well as deburring of edges 12, 13, 14 and 16, 17, 18 ( Figures 5 to 13 In the third stage, an anti-rotation hole 38 for accommodating an anti-rotation element 39 is punched out on the blank 1 ( Figure 17 and Figure 18 ). Then, a heat treatment is performed to harden the blank 1 and then fine grinding is performed. In the final stage, the cam roller 40 is installed in the housing 3 and the cam roller pin 41 is installed in the through holes 9, 10 on the finished housing 42 ( Figures 17 to 19 ). The proposed roller tappet is thus produced according to the aforementioned method and used in an internal combustion engine.

[0058] Figures 17 to 19Figure 4 shows a roller tappet 44 manufactured according to the aforementioned method. The elongated cylindrical housing 42 of the roller tappet 44 serves to guide the roller tappet along the longitudinal axis 2 at its outer diameter in the bore of the internal combustion engine. At the drive-side end of the housing 42, a cam roller 41 is rotatably mounted on a cam roller pin 41 in a receptacle 3. The cam roller 41 protrudes slightly from the housing 42 to establish cam contact with the camshaft. At the driven-side end of the housing 42, a pump contact portion 4, integrally formed with the housing, protrudes centrally. Four flattened portions 5 to 8 on the outer diameter of the housing 42 significantly reduce its mass and simultaneously provide a lightweight design with thin walls. This lightweight design increases the dynamics of the roller tappet during operation. The outer periphery of the housing 42 remains completely cylindrical at the driven-side end section 43 and in the central regions 27 and 28. The edges 12 to 18 extending in the circumferential direction, which are produced by producing flattened portions 5 to 8 on the outer diameter of housing 42, are deburred with low-notch effect by using concavely turned rounded portions 29, and each of these edges forms a low-notch groove 30 on the cylindrical outer circumference of housing 42. Groove 30 has a slightly circular cross-sectional profile and a small cut-in depth. An anti-rotation element 39 arranged in anti-rotation hole 38 in blank 1 ensures that the roller tappet does not rotate during operation in a bore (not shown) for guiding the tappet in an internal combustion engine.

[0059] Reference Signs List

[0060] 1 blank

[0061] 2 Cylinder axis, longitudinal axis

[0062] 3. Accommodation

[0063] 4 Pump contact part

[0064] 5 Flattened part

[0065] 6 Flattened part

[0066] 7 Flattened part

[0067] 8 Flattened part

[0068] 9 through holes

[0069] 10 through holes

[0070] 11 Edges extending in the circumferential direction, longer edges

[0071] 12 Edges extending in the circumferential direction, longer edges

[0072] 13 Edges extending in the circumferential direction, longer edges

[0073] 14 Edges extending in the circumferential direction, longer edges

[0074] 15 Edges extending in the circumferential direction, longer edges

[0075] 16 Edges extending in the circumferential direction, longer edges

[0076] 17 Edges extending in the circumferential direction, longer edges

[0077] 18 Edges extending in the circumferential direction, longer edges

[0078] 19Axial edges, shorter edges

[0079] 20Axial edges, shorter edges

[0080] 21Axial edges, shorter edges

[0081] 22Axial edges, shorter edges

[0082] 23Axial edges, shorter edges

[0083] 24 axial edges, shorter edges

[0084] 25Axial edges, shorter edges

[0085] 26Axial edges, shorter edges

[0086] 27 Middle Area

[0087] 28 Middle Area

[0088] 29 Deburring part, convex rounded part

[0089] 30 grooves

[0090] 31 Forming molds, turning tools

[0091] 32 die cutting edge

[0092] 33 Concave rounded portion

[0093] 34 Forming mold, turning tool

[0094] 35 mold cutting edge

[0095] 36 forming mold, turning tool

[0096] 37 Die cutting edge

[0097] 38 anti-twist hole

[0098] 39 Anti-rotation element

[0099] 40 Cam roller

[0100] 41 Cam roller pin

[0101] 42 housing

[0102] 43 end section

[0103] 44 Roller tappet

[0104] S wall thickness

[0105] s wall thickness

Claims

1. A method for producing a roller tappet (44) for a pump mechanism or valve mechanism of an internal combustion engine, the roller tappet having a cylindrical housing (42) for guiding the longitudinal movement of the roller tappet (44) in a bore of the internal combustion engine, characterized in that The cylindrical blank (1) of the housing (42) is manufactured in a lightweight structure, is provided with at least one flattened portion (5, 6, 7, 8) on the outer diameter of the blank (1), and is deburred with a low notch effect by turning at least one edge (11 to 18) formed on the outer diameter of the blank (1) in an intermediate area between the axial ends of the blank (1).

2. The method according to claim 1, characterized in that In order to achieve a deburring process with a low notch effect, a slightly concavely curved radius (29) is produced by turning on one or more edges (11 to 18).

3. The method according to claim 1 or 2, characterized in that One or more flattened portions (5, 6, 7, 8) are machined to be rectangular in radial top view, each of which has two edges (11 to 18) perpendicular to the cylindrical axis (2) of the blank (1) and extending in the circumferential direction and two edges (19 to 26) extending parallel to the cylindrical axis (2).

4. The method according to any one of claims 1 to 3, characterized in that The blank (1) is machined at its outer diameter to have at least two flattened portions (5, 6, 7, 8) arranged in sequence in the axial direction and at least two flattened portions in the circumferential direction, and edges (12 to 18) extending in the circumferential direction formed at the flattened portions are deburred in one process by turning.

5. The method according to claim 4, characterized in that The flattened portions (5, 7 and 6, 8) are produced at intervals of 180° from each other in the circumferential direction.

6. The method according to any one of claims 1 to 5, characterized in that The blank (1) having a hollow structure is manufactured by an extrusion molding process, wherein the blank (1) has a receiving portion (3) for arranging a cam roller (41) which is in the shape of a long hole in a top view starting from an axial end, so that the wall thickness (S) of the blank (1) on the longitudinal side of the receiving portion (3) is greater than the wall thickness (s) on the end side of the receiving portion (3), wherein the flattened portion is provided on the outer diameter region of the blank (1) having the larger wall thickness (S), so that the blank (1) has a thin-walled structure.

7. The method according to claim 6, characterized in that At least one flattened portion (5, 7) is machined starting from an axial end of the blank (1) for accommodating the cam roller (41) in the accommodating portion (3).

8. A forming die (31, 34, 36) for manufacturing a roller tappet (44) of a pump mechanism or a valve mechanism of an internal combustion engine, wherein the roller tappet (44) is manufactured according to the method according to any one of claims 1 to 7, characterized in that: The forming die (31, 34, 36) has a die cutting edge (32, 35, 37) having a forming profile including at least one convex rounded portion (33) for deburring at least one edge (12 to 18) produced by turning on the outer diameter of the blank (1) of the housing (42) of the roller tappet (44) with a low notch effect.

9. The forming die (31, 34) according to claim 8, characterized in that: The die cutting edges (32, 35) have a profile with a plurality of convexly curved radii (33) for simultaneously deburring, by turning, a plurality of edges (12 to 18) produced by flattened portions (5, 6, 7, 8) produced at the outer diameter of the blank (1) of the housing (42) with a low notch effect.

10. A roller tappet (44) for a pump mechanism or valve mechanism of an internal combustion engine, characterized in that The roller tappet (44) is produced in a lightweight structure according to the method according to any one of claims 1 to 7.

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