RU2150358C1 - Method and apparatus for electrochemical working of cutting edges of tool - Google Patents

Abstract

FIELD: processes for forming cutting edges of blade-type tools. SUBSTANCE: method comprises steps of using at least one movable electrode at working; sharpening cutting edges due to creation of electric field at screening end of blank in zone of sharpening; interrupting motion of electrode before termination of working when thickness of blank at side of its end consists 0.2-0.5 of interelectrode gap value; completing working when electrode is fixed. Apparatus for performing the method includes electrode with working surface identical to shape of cutting edge of tool. Dielectric screen has recess opposite sharpened edge. Dimension of said recess corresponds to size of working interelectrode gap. Surface of electrode turned to sharpening zone has flat portion. It is possible to make blade-type tools with radius of sharpened edge less than 2 micrometer. It provides useful life period of tool increased by 1.5-2 times due to reduced number of operations for regrinding and dressing tool. EFFECT: increased service life of tool. 2 cl, 3 dwg

Description

 The invention relates to the field of dimensional electrochemical processing of metals and can be used to form cutting edges of blade tools.

 Known methods of electrochemical processing, allowing the formation of complex surfaces / 1 /, which shows the method of electrochemical volumetric copying using a movable electrode, the geometric shape of which is displayed in the workpiece. This method allows the formation of faces of any shape on workpieces of any thickness. The disadvantage of this method is the inability to obtain sharp cutting edges for the reason that at the initial moment of processing the rounding of the edge occurs, since it is closest to the surface of the electrode and in the process of further shaping the radius of the edge remains constant and can only increase.

 A known method of electrochemical sharpening of the ends of the parts / 2 /.

 The method according to the specified invention is carried out using two stationary electrodes located opposite the edges of the sharpening at a converging angle of 15-25 degrees more than the angle of the required sharpening, while the electrodes are set so that the end face of the workpiece protrudes beyond the edge of the electrodes by the value of the average interelectrode gap established at the beginning of processing, and the length of the faces of the electrodes is chosen equal to the difference between the lengths of the edge of the point and the specified gap. However, firstly, this method is suitable for forming only flat faces and does not allow for “razor” or wedge-shaped sharpening of the cutting tool, and secondly, because the angle of convergence of the electrode faces exceeds the angle of convergence of the cutting edges of the workpiece at the end of processing predominant etching of the tip occurs and, as a result, its blunting. In addition, when cutting faces are formed on workpieces with a significant thickness (more than 3 mm), the electrode gap at the end of processing exceeds 4-5 mm, which leads to significant energy costs for overcoming the electrical resistance of the electrolyte, its intense heating and requires efficient cooling.

 The closest is the invention according to patent RU 2069126 C1, B 23 H 3/00, 7/22, 7/26 "Method for electrochemical flashing of holes and a device for its implementation" from 11/20/96 / 3 /. This method provides for a tight fit of the workpiece at the places of formation of the output edges of the stitched holes. In this case, the electrochemical treatment (ECHO) is started with a vibrating electrode-tool (E-I), the working surface of which has a shape identical to the shape of the cutting face on a pulsed current. Then, after cutting EI to a depth less than the thickness of the workpiece by the value of the equilibrium end gap, the working supply of EI is stopped. Then set the processing mode, providing the greatest localization of the ECHO process and maintain the EI in this position until the hole is completely opened and the specified radius of the output edge is formed. This method is suitable for machining precision parts with straight cutting edges of small length holes. The disadvantages of this method include the impossibility of processing workpieces with a thickness of more than 0.15-0.2 mm with a radius of curvature of the cutting edge of less than 2 microns.

 The objective of the invention is to obtain the cutting edges of the tool with a radius of the tip less than 2 microns. The problem is solved due to the fact that the electric current field in the interelectrode gap between the movable electrode and the workpiece is formed so that the angle of convergence of the cutting faces at the point of sharpening at the end of processing is 1-2 degrees, while the surface of the end face of the workpiece in the zone of formation of the tip is screened , and before the end of processing, when the thickness of the workpiece in the zone of formation of the tip is 0.2-0.5 of the working interelectrode gap, the movement of the electrode is stopped and the final processing is completed by a fixed electrode.

 As a prototype of a device for implementing the proposed method, a structural scheme for implementing the known method / 3 / is selected.

The inventive device is illustrated in the drawing, where:
in FIG. 1 shows the arrangement of elements at the beginning of processing,
in FIG. 2 - the location of the elements at the time of termination of the movement of the electrode and
in FIG. 3 - arrangement of elements at the end of processing.

 The device comprises a movable electrode 1 with a working surface 2 having a shape identical to the shape of the cutting edge of the tool; a flat section 3 parallel to the plane of the workpiece, the width of which is 0.5-1.2 of the working interelectrode gap; a dielectric screen 4, fixed with respect to the workpiece, mounted on the side of the end face of the workpiece and having a sample 5, the width and depth of which is 0.5-1.0 of the working interelectrode gap.

 The optimal values of the technological parameters of the method and the dimensions of the structural elements of the device are determined from the experiment. The convergence angle of the cutting faces of less than 1 degree is not structurally justified due to the insufficient rigidity of the tip, and the angle of more than 2 degrees does not provide a tip radius of less than 2 microns, which reduces the cutting properties of the tool. The thickness value from the end face of the workpiece at the time of stopping the movement of the electrodes is less than 0.2 of the interelectrode gap leads to local blunting of the cutting edge, and more than 0.5 of the gap leads to unevenness of the radius of rounding of the tip along the length of the cutting faces. The sample size in the dielectric screen in width and depth of less than 0.5 interelectrode gap contributes to the appearance of waviness along the length of the tip, and more than 1.0 gap to traces of jet along the length of the cutting faces. The width of the flat portion of the working surface of the electrode is less than 0.5 of the interelectrode gap does not provide the required radius of rounding of the tip, and more than 1.2 of the gap leads to local etching and blunting of the tip.

 Before the start of processing, the workpiece is provided with a technological allowance in width equal to the width of the flat portion of the electrode working surface, and during processing, the allowance is etched parallel to the flat section. After the electrode stops and processing continues when the electrode is stationary, due to the redistribution of the electric field in the interelectrode gap, accelerated etching of the tip film along the edge and formation of the convergence angle of the cutting faces within 1-2 degrees occur.

 Example. Using the inventive method and device, a batch (10 pcs.) Of cutter knives for industrial meat grinders from a strip of stainless steel grade 55X15MF with a thickness of 8 mm was made. Preforms were machined along the contour and planes, then heat treated (quenching to hardness HRC 60-62). After manufacturing, measurements were made of the radius of rounding of the tip using an electron microscope, the measurement results showed that all knives have a radius of the tip of less than 2 microns.

 Achieved technical result will improve the consumer properties of the final product due to finer grinding and increase the service life of knives by reducing their resharpening and editing.

Sources of information
1. Handbook of electrochemical and electrophysical processing methods. Authors: G. L. Amitan et al. Under the general. ed. V.A. Volosatova, L., Mechanical Engineering, 1988, p. 20.

 2. Auth. testimonial. USSR N 1220909, B 23 H, 9/08, 1986

Claims (2)

 1. The method of electrochemical processing of the cutting edges of the tool, including the use of at least one movable electrode, the working surface of which has a shape identical to the shape of the cutting edge, and the formation of an electric current field in the working interelectrode gap, providing sharpening of the cutting edges due to the initial movement of the electrode at the beginning of processing, the termination of the movement of the electrode before the end of the processing and the process of final processing with a stationary electrode, I mean that the surface of the end face of the workpiece of the tool in the zone of formation of the tip is shielded, while the movement of the electrode is stopped when the thickness of the workpiece in the zone of formation of the tip is 0.2 - 0.5 of the working interelectrode gap.  2. Device for electrochemical processing of cutting edges of a tool, comprising an electrode, the working surface of which has a shape identical to the shape of the cutting edge, characterized in that it is provided with a dielectric screen fixed to the tool blank, mounted on the side of the workpiece end, having a sample opposite the forming tip the width and depth of which is 0.5 - 1.0 of the magnitude of the working interelectrode gap, while the working surface of the electrode facing the zone of formation of the tip has a flat a section parallel to the plane of the workpiece, the width of which is 0.5 - 1.2 the magnitude of the working interelectrode gap.

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