Method for making plungers of telescopic hydraulic cylinders

The invention relates to mechanical engineering and can be used for the manufacture of plungers for long stroke telescopic cylinders in the automotive industry, agricultural machinery and road construction.

A known method of manufacturing parts like rods, plungers, hydraulic cylinders, axles, pins, combining cutting and plastic deformation on a lathe. The method includes rotating the workpiece and moving them simultaneously from the guide sleeve to the spindle along the details of the processing head with the cutting and deforming parts installed with the possibility of oscillations, and the cutting part in the process stabilizes the position of the parts in the direction of reservoirthe, and before processing to detail make the tensile stress with the subsequent imposition of an oscillating movement in the axial direction (patent No. 2134631, class B 24 B 39/04, 1999).

The disadvantages of this process lie in the complexity of the technological process of production of parts and system selection based cutting and deforming parts.

Closest to the claimed object is a method for manufacturing parts such as hollow cylinders, mainly parts of the telescopic cylinder housing and plungers with a multistage machining parts is from: turning and running-in of the outer surface, boring and rolling the inner surface, trim the ends, cutting the inner and outer grooves and processing chamfers (patent No. 2049648, class B 23 Q 41/00, 1995).

The disadvantage of this method is the complexity of technology, which consists in multistage machining, and significant loss of metal shavings up to 50%. Obtained in this way items have low strength characteristics due to the fact that the cutting does not provide change (seal) patterns of the inner and outer surfaces of the part. In addition, the details obtained in this way, require complex finishing operations to obtain the required surface roughness as on the outer and inner diameters of the workpiece. A significant disadvantage of this method is its unacceptability for the manufacture of parts of long stroke cylinders.

The invention is directed to a simplification of the manufacture of the plungers with the simultaneous reduction of metal loss, improved surface quality and increased durability of the parts. In addition, the task of making the proposed method, details of long stroke cylinders.

This is achieved in that in the method of manufacturing plungers for telescopic hydraulic cylinders, including the treatment of inner and outer surface the values of the parts, trim the ends and chamfer, processing parts carry cold rolling.

The method is as follows.

The workpiece in the delivery process of rolling mill by plastic deformation simultaneously on the inner and outer surfaces of the cold rolling, followed by trimming the ends of the items received.

Example. Was the pilot batch of plungers for telescopic hydraulic cylinders cold rolling of billets made of structural steel with subsequent trimming of the obtained details. The structure of the original metal - grained 4-7 points according to GOST 5939-82, perlite, surrounded by a grid of ferrite, with the original hardness HB 170. Hardness after rolling is 240 HB. In all cases, after rolling was observed elongation of the grains along the axis of the billet.

As starting material for the manufacture of the plungers is selected normalized pipe rolled from steel grades 35 or 45 of the respective sizes.

The first operation involves cutting dimensional billets for rolling batches of the same size, then make consecutive rolling each blank with the simultaneous receipt of the required cross sectional dimensions and surface finishes of the product due to the rolling tool clips on the outer surface and Oprah is key as snap-on inner surface. Processed by cold rolling the product is removed from the mill and subjected to trimming the ends and chamfering.

The use of the proposed method will allow for a comparison with the prototype to simplify the manufacturing technology plungers for telescopic hydraulic cylinders due to the replacement of multistage machining, where each step requires its own equipment, in a single operation - cold rolling. In addition, this reduces metal loss to 2%, i.e. is achieved by the utilization of metal to 0.98, whereas in the method according to the prototype during mechanical processing of metal loss up to 50%, and improves the quality details: receive a mirrored outer and inner surface (in the method according to the prototype of the item received is necessary to ensure the required surface finish grind and Polish, which is a rather time-consuming and complex operations). In addition, when using the proposed method is the seal of the metal grains and the improvement of its structure, as well as getting a different view of the surface on the outer and inner surfaces of the parts that will improve the strength characteristics of the resulting parts. The proposed method allows to produce parts for long stroke cylinders (the way ABM is otipo for the manufacture of long stroke cylinders unsuitable).

A method of manufacturing plungers for telescopic hydraulic cylinders, including the processing of the inner and outer surfaces of the parts, trimming the ends and chamfer, characterized in that the workpiece parts processed in the rolling mill by plastic deformation simultaneously on the inner and outer surfaces of the cold rolling to obtain a mirror surface, followed by trimming the ends of the items received.