DE1049197B - Device for cold hammering of crankshafts for internal combustion engines - Google Patents

Description

The invention relates to a device for cold hammering in order to achieve an increased Fatigue strength of crankshafts for internal combustion engines to improve the local strength of the starts to increase the crank pin.

It is well known that certain metals and especially steels acquire a significant amount after cold hammering Tensile strenght. If the cold hammering is carried out correctly, appropriately selected results will result Zones of internal stresses that improve the perceptible or apparent fatigue limit favor the treated workpiece. Since with a crankshaft for internal combustion engines the starts If dynamic stresses are concentrated at certain points on the crank arms, it is appropriate to to carry out cold hardening at these stress centers.

It is known that the work hardening on fillets and grooves of motor shafts by means of a so-called Perform smoothing roll. However, this tool does not allow economical machining and is suitable therefore not for larger quantities.

Tests for the purpose of determining the apparent fatigue limit in the case of torsional bending loads on a chromium-nickel steel sample treated in the mass for R - about 100 kg have shown the following comparative results:

Apparent fatigue limit in kg / mm ²

1. Sample without groove, without machining 46

2. Sample with groove, without mechanical
Processing 22

3. Sample with grained groove 22

4. Sample with groove and thermal surface treatment (inductive heating

the groove and hardening) 30

5. Sample with hammered groove 32.5

The object of the invention is to create a simple device that hammering the crankshafts in large-scale operations through the simultaneous treatment of the two approaches of a crank pin despite their difficult accessibility for an ordinary chisel.

The device according to the invention is characterized by a one that can be pushed astride the crank pin Tool holder in which od under the impact of a pneumatic hammer. Like. A rod is movable, whose end facing away from the hammer acts on the two hammer bits, the V-shaped are arranged in a holder in such a way that they rest on the two approaches of the crank pin.

In the drawing show:

Device for cold hammering of crankshafts for internal combustion engines

Applicant:

Directed by Nationale des Usines Renault, Billancourt, Seine (France)

Representative: Dr.-Ing. E. Liebau, patent attorney, Göggingen near Augsburg, Von-Eichendorff-Str. 10

Claimed priority: France of February 15, 1956

Fig. 1 shows an embodiment of a device according to the invention in view of the crankshaft,

FIG. 2 shows the tool located in the working position on a crank pin in a section corresponding to the line ab in FIG. 1,

Fig. 3 is a detailed view of a chisel or hammer chisel,

Fig. 4 shows the drive rod shown in Fig. 2 for the hammer tools.

The device shown in FIGS. 1 and 2 has a support or carrier 30 with a U-shaped cross section on ,, whose legs run down in two curved arms 35, which are in the working position encompass the circumference of the crank pin 21 of the crankshaft partially shown in FIG. 2. These is provided with the crank arms 22 and 23 and the crank pin 24.

Within the holder 30, a rod 31 is mounted with play. It is on three sides of the Bracket 30 and, on the fourth side, guided by the bolts 33 that form the legs of the bracket enforce and are secured by split pins 38. A projection 27 and a collar 26 limit the longitudinal movement of the rod 31 in the holder 30.

At the lower end of the rod 31 are two small caulking tools 32 a, 32 δ V-shaped and arranged are made in a ring 25 and a web 41

809 730/255

Claims (1)

3 4 Rubber or an oil-resistant, elastic synthetic moment in m kg of material held in place. a) for a cast steel crankshaft without The ring 25 is around the bracket 30 and the usual treatment 53.8 Rod 31 held taut, to which b) after a crankshaft made of cast steel Purpose in the holder 30 also the grooves 36 5 cold hammering 97.5 and 37 are provided. A pin 34, the two c) with a crankshaft made of cast steel Arms 35 of the holder 30 penetrated, is used for the fixed undercut 58.1 hold the web 41. d) with a crankshaft made of cast steel This elastic fastening only has the hammered undercut 116.7 Purpose, the two caulking tools so firmly io ten that these can be adjusted against each other, freely and, patent claims:
as FIG. 2 shows, can slide into the approaches 28 and 29 of the crank pin 21 of the crankshaft. 1. Device for cold hammering the approaches Each caulking tool is made of a high carbon steel on the crank pins of crankshafts for cutting of the chisel steel type and has a wedge-cutting power tool for the purpose of obtaining an increased borrowed cross-section with rounded edges, as illustrated by the increase in fatigue strength of the local Fig. 3. One end 42 has a strength, characterized by a radius of curvature astride, the value of which comes very close to that of the tool-handling approach that can be pushed onto the crank pin, and the two holders (30), in d <em under the impact of a surface 39 and 40 have a rounding with a large 20 air hammer or the like. A rod (31) be-curvature radius. The angles which the individual can move, whose ends facing away from the hammer form surfaces with one another, are determined in such a way that the resultants F ¹ and F ² of the chisels act on the two hammer bits (32 a, 32 b), the V- shaped in a holder in Rich transmitted forces run perpendicular to the curvature of the tang to the two approaches of the crank pin machined approach. The end 44 of the 35 (21) are guided. Rod 31 is used to receive the blows of a 2. Device according to spoke 1, characterized gePreßlufthammers or any other device which indicates that the holder from a ring has the same effect. At its opposite (25) and a strut (41) made of rubber or elastic end, the rod 31 has a flat surface 43, which consists of the Schem plastic.
Mortising tools acted upon. 30 3. Device according to one of the preceding The operation of the device is as follows: Claims, characterized in that each The apparatus is astride the hammer chisel to be machined (32 a, 32 b) from a wedge-shaped the crank pin pushed on, and the example piece of steel with rounded edges is made, wise blows exerted by a jackhammer in which one end (42) has a curvature hit the end 44 of the rod 31. This transmits the. 35 radius or shark knife that approximates the Strikes with their other end 43 on the cylindrical curvature radius of the workpiece to be machined drical back 39 of the chisel, which corresponds to the barrel, while the other end two their other cylindrical back 40 against each other surfaces (39, 40) with large curvature semi- prop up. These chisels in turn transfer the knives, with the two tools Strikes through their lugs 42 on the approaches 28 and 40 (32 a, 32 V) with one of the surfaces (40) against each other 29 whose hard hammering is desired. are supported and the other surface (39) on the In order to achieve an even hammer effect in the striker rod (31). To achieve directions of the resultants P ¹ and F ^2, it is sufficient to remove the crankshaft and the tool during the documents considered:
the processing evenly against each other to 45 German patent specifications No. 743 647, 287 853,
turn. 151486; The comparative tests with flat bending ■ USA. Patents Nos. 1849 078, 1468 507; Vehicle crankshafts that have been tested for fatigue have "Workshop Technology and Mechanical Engineering" from led to the following results: August 1952, p. 340. 1 sheet of drawings © 809 730/256 1 59