Showing papers on "Roller burnishing published in 1998"

Roller burnishing of hard turned surfaces

Abstract: In a hard roller burnishing operation, a hydrostatically borne ceramic ball rolls over the component surface under high pressures The roughness peaks are flattened and the quality of the workpiece surface is improved When combined with hard turning, this process provides a manufacturing alternative to grinding and honing operations The studies determined optimum working parameter ranges Parameter settings were shown to be non-critical in this process, since constant surface qualities were attainable over wide setting ranges A second phase of the studies examined the improvements obtained for various original roughnesses Reductions of 30 to 50 % in mean peak-to-valley height Rz are, for example, achievable, depending on the original roughness Structure analyses and residual stress measurements were used to examine the effects of the process on the workpiece surface zone Hard roller burnishing transforms tensile residual stresses present in the surface zone after hard turning into compressive residual stresses Hard roller burnishing has no effect on the formation of white layers in the surface zone

The 3-D characterisation of the surface topography of the ballizing process

Abstract: Engineering surfaces are produced by a large number of manufacturing processes and once the processing is complete they are left with a surface texture which reflects the machining operation. Boring, turning, milling, grinding, lapping and honing are typical machining process, whilst roller burnishing and ballizing are typical of processes where improved surface finish as well as modified surface properties are required. These latter two processes, which have been in common usage for many years, have advantages which have not yet been fully explored. This includes the ability to deliberately impart negative residual stresses into the surface which are advantageous in improving the functional life of often stressed components as well as improved surface texture. The main purpose of this paper is to investigate the trends of roughness and residual stress related to the parameters of the ballizing process. This paper uses the 3-D surface evaluation techniques to characterise the ballized (engineered) surface and uses the ring cut-off method to calculate the residual stress on its circumference. This experimental methodology and analysis are used to show that: 1) The wall thickness of the ballized component and the interference amount are significant causes of roughness and residual stress. 2) The speed of the ball (velocity) going through the holes has a little effect on the roughness and residual stress.

Burnishing machine for crankshafts

Abstract: The invention relates to a roller burnishing machine, in which the force device (13) is mounted in manner that enables it to be displaced along the direction (30) of its force effect inside a gate (31). The force unit (13) is, via one end (32), connected in an articulated manner by means a joint (33) to the end (11) of a shearing arm (3) of the roller burnishing unit (15). The free end (34) of the gate (31) is provided with a guide roll (35), which is guided along a curved path (36) that is recessed in the end (11) of the shearing arm (3). Three joints (28, 29, 33) form a triangle (37) when the force unit (13) is in the closed position. One of the joints (28) points toward the rotating joint (5) via which both shearing arms (3 and 4) of the roller burnishing unit (15) are connected to one another in an articulated manner. When the force unit is in the closed position, a bent lever (27) rests against the stop (39) at the end (12) of the shearing arm (4).

Sliding member made of aluminum alloy and cylinder made of aluminum alloy

Abstract: PROBLEM TO BE SOLVED: To easily obtain a sliding member made of an Al alloy having a smooth surface and low in the coefficient of fraction by applying a basis composed of an Al alloy with an anodic oxide layer and working the projecting tip parts of alumina particles projecting at random on the surface into a flat shape by roller burnishing tools. SOLUTION: An anodic oxide layer is formed on the internal face of a cylinder 1 made of an Al alloy by aodic oxidation treatment. The anodic oxide layer on the internal wall 2 is subjected to smooth working by roller burnishing tools 3 formed by providing a supporting body 5 with plural rollers 4. In this way, the tip parts of alumina particles uniformly projecting in the anodic oxide layer are indented, and the surface is smoothly subjected to mirror finishing. At this time, the recessed parts among the alumina particles are allowed to remain to secure the retaining parts of lubricating oil. Furthermore, particles for compounding such as solid lubricants are previously applied and stuck to the surface of the anodic oxide layer, and the working is executed by the roller burnishing tools, by which the smoothing of the anodic oxide layer is attained, and furthermore, the grains for compounding can easily and uniformly be dispersed therein.

Method of improving fatigue strength of screw of tie-bar and roller burnishing device

Abstract: PROBLEM TO BE SOLVED: To provide a method and a roller burnishing device for improving the fatigue strength of a tie-bar by means of an inexpensive roller burnishing device without requiring an increase in diameter, or an extremely large, expensive rolled thread cutting device. SOLUTION: In the threading method for tie-bars, a specified length from the end face of an end of a tie-bar 2 is first threaded by an NC lathe, and then the roots of an external thread are burnished. Besides, the roller burnishing device is composed of a roller 11, a holder 12 for rotatably holding the roller 11, and a case 13 for supporting the holder 12 turnably around the axis through a compression spring 17.

Roller burnishing device

Abstract: PROBLEM TO BE SOLVED: To provide a roller burnishing device capable of simultaneous centerless rolling compaction working of the inner and outer peripheral surfaces of a cylindrical pipe toe be worked. SOLUTION: The roller burnishing device is provided with a mandrel 4 which is arranged in the cylindrical inside of roller frames 5, 6 and which rollably abuts on the internal working rollers 2, and a cylindrical head 3 which is arranged so as to surround the outer periphery of the roller frames 5, 6 and which rollably abuts on the outer peripheral surface of external working rollers. The internal working rollers 2 and the external working rollers 1 are structured in pairs to be positioned on the same radials with respect to a center shaft to be faced with each other, and the number of both the rollers is the same. The internal working rollers 2 and the external working rollers 1 are arranged to have a specified feed angle by which the feed quantity of the cylindrical pipe to be processed is the same on the inner and outer peripheral surfaces. In relation to the direction of relative rotation, the roller frames 5, 6 are rotated-driven, the mandrel 4 is rotatably held, and the head 3 is fixed.

Manufacture of common rail

Abstract: PROBLEM TO BE SOLVED: To prevent projecting and recessed parts and fine cracks produced on the inner peripheral surface of a flow passage by rotating a roller relatively to a common rail to perform burnishing for the inner peripheral surface of a flow passage while tapping. SOLUTION: A roller burnishing device RB comprises plural rollers 2 for pulling a mandrel 1 axially relatively to a common rail 10 and engaging with the mandrel 1 on a conical surface 1a formed on the outer peripheral surface of the mandrel 1 to be freely rotated, and a retainer 3 for retaining the rollers 2 on the conical surface 1a of the mandrel 1. A burnishing device RB is introduced into a hollow part of a common rail 10 to be worked, so that plural rollers 2 rolling on the conical surface la of the mandrel 1 conducts rolling compaction for the inner peripheral surface 11 of the flow passage to perform roller burnishing. Thus, cracks and creased of the inner peripheral surface 11 of the flow passage can be prevented by rolling compact and tapping operation of the rollers 2.