FR2845300A1 - PROCESS AND TOOLS FOR DEBURRING BY ELECTROCHEMISTRY - Google Patents

Abstract

Process for electrochemical deburring of a part (2) to be deburred, in which the part (2) is placed in a tool (1) bearing against positioning stops (71, 81, 72, 61), at least one of said stops (61) being retractable, the retractable stopper (61) is retracted, at least one electrode (61, 95) is brought close to the part (2), characterized in that one of the stops retractable (61) is at least one of the electrodes. Tool for implementing the method.

Description

Method and tool for deburring by electrochemistry.

  The invention relates to a method and a tool.

deburring by electrochemistry.

  Deburring sharp edges on machined parts can be done for example by brushing or shot blasting. However, these methods modify the geometry or the surface condition more widely than the area to be deburred. Deburring can also be carried out by machining, by making a chamfer for example with a chamfering cutter. The geometry 10 obtained may not be suitable for the use of the part, or may be difficult to obtain. In addition, there is

often still edges.

  Electrochemical processes make it possible to round off sharp edges, with a radius of curvature that is easy to control, without modifying the geometry or the surface condition of the areas surrounding the edge to be deburred. For this, an electrode of a shape adapted to the edge is approached to the edge, retaining a space called the air gap between the part 20 and the electrode. The air gap is filled with electrolyte and a current is established between the part and the electrode, which erodes the part at the air gap. For the implementation of such a method, it is necessary to ensure good relative positioning of the electrode and the part. This positioning is conventionally achieved by means of a tool which allows the mounting of the part. This tool comprises stops on which the reference surfaces of the part are supported, and clamping means which

  block the part after it has been positioned.

  In some cases, reference surfaces 5 are difficult to access and the stops would hinder the positioning of the electrode. In this case, it is generally known to retract at least one stop after tightening the part to free access to the edge to be deburred. However, this solution 10 requires the provision of means for retracting the stop in addition to the means for positioning

  the electrode, which makes the tool complex.

  It is therefore an objective of the invention to provide a method of deburring by electrochemistry 15 making it possible to simplify the positioning of the part.

to deburr.

  With this objective in view, the invention relates to a process for deburring by electrochemistry of a part to be deburred, in which the part is placed in a tool bearing against abutments of

  positioning, at least one of said stops being retractable, the retractable stop is retracted, at least one electrode is approached near the workpiece, characterized in that one of the retractable stops 25 at least is one of the electrodes.

  Thus, thanks to the invention, the retractable electrode has, in addition to its electrode function, a stop function. The part to be deburred is first placed in abutment against the retractable electrode 30, then the retractable electrode is moved to its working position, generally a few tenths of a millimeter from the edge to be deburred. As two functions are fulfilled by the

  same element, the tooling is simplified.

  Generally, the retraction of the electrode can be done by a simple translation. The support is for example made on a surface of the part limited by the edge to be deburred. In this case, the displacement of the electrode takes place along this surface, with a clearing trajectory, or parallel to the surface, the electrode ending in a bevel coming to be placed facing the edge at the end. of retraction. It is also an objective of the invention to provide a tool for deburring by electrochemistry 15 making it possible to simplify the positioning of the part.

to deburr.

  With this objective in view, the invention relates to a deburring tool for the preceding process, the tool comprising: - stops for positioning a part to be deburred, at least one of the stops being retractable - at least one electrochemistry electrode; characterized in that at least one of the electrodes

is a retractable stop.

  Preferably, the hardness of the electrode

  retractable is greater than 55 Hrc (Rockwell hardness). The electrode is thus resistant to wear. In the case of surface hardness, an equivalent Vickers hardness may be specified.

  In particular, the retractable electrode is made of metal carbide. This material is indeed very hard. Furthermore, the inventor has surprisingly found that it is sufficiently conductive to perform the function of electrode. A suitable material has for example ISO reference: K20 or K40. Alternatively, the metal carbide is deposited on the surface of the electrode, to provide surface hardness and wear resistance, and the core of the electrode is in a more conductive material, such as steel

or copper.

  In a particular embodiment, the retractable electrode is a cylindrical rod 15 terminated by a narrowed zone, the part comprises a hole, the part coming into abutment against the retractable electrode in the hole, the electrode performing the deburring of the entrance to the hole. In this configuration, the retraction of the electrode is carried out by a translation in the axis of the bore towards the outside of the part, until the narrowed zone is opposite the entry. drilling. Due to the narrowing, the electrode is no longer in contact with the part, but a space is created between them, the latter thus forming the air gap for the electrochemical operation. The narrowed area is by

  example a truncated cone or a rounded one.

  Preferably, the electrode is hollow and channels an electrolytic liquid. The filling of the air gap with the electrolyte is thus achieved without the need to fully soak the part in a bath. The invention will be better understood and others

  particularities and advantages will appear on reading the description which follows, the description referring to the attached drawings among

  which: - Figure 1 is a sectional view along line II of Figure 2 of a tool according to the invention; Figure 2 is a partial sectional view along line II-II of Figure 1; - Figure 3 is a detailed sectional view along line III-III of Figure 1, the tool being in the open position;

  - Figure 4 is a view similar to Figure 3, the tool being in the closed position.

  The tool 1 in FIGS. 1 and 2 is provided for deburring a cylindrical part 2, in which a diametrical hole 21 has been made. The edges to be deburred are the intersections of the diametral bore 21 and of the external cylindrical surface 22 of the part 2. The orientation of this part 2 is only possible with reference to the hole 21. To position the part, in particular for carrying out deburring by electrochemistry, it is necessary to rest on the interior surface of the bore 21. A stop introduced in the bore must be

  retracted to perform deburring.

  The tool 1 according to the invention is intended to be mounted between two plates of a machine, a lower plate 3 and an upper plate 4. The distance between the two plates 3, 4 is variable between an open position and a position closed visible in FIGS. 1 and 2. The tool comprises a base 5, clamped on the lower plate 3 by flanges 51, a lower electrode support 6 and a lower mounting plate 7 arranged parallel to the base 3. The lower mounting plate 7 is rigidly fixed to the base 3 by spacers 31, while the lower electrode support 6 is slidably mounted on said spacers 31. Base springs 32, mounted around the spacers 31, tend to push the lower electrode holder 6 into abutment against the lower plate of

mounting 7.

  The tool 1 also includes an upper mounting plate 8 and an electrode support

  upper 9. The upper electrode support 9 is rigidly fixed on the upper plate 4, for example by screws 41. Columns 91, of axis parallel to the spacers 31, are mounted on the underside of the electrode support upper 9.

  The balusters 91 include a guide zone 92 on which the upper mounting plate 8 can slide. A baluster head, with a diameter greater than the guide zone, forms a stop for the upper mounting plate 8. Upper springs 94, mounted around the balusters 91, tend to keep the upper mounting plate 8 in abutment against the baluster head. The baluster heads extend in the direction of the lower electrode support 6 to come to bear therein.

the closed position.

  The mounting plates 7, 8 and the electrode supports 6, 9 are made of electrically insulating material. The lower mounting plate 7 and the upper mounting plate 8 have indentations respectively lower 71 and upper 5 81, of substantially semi-cylindrical shape, the diameter of the part to be deburred 2. The indentations serve as a stop for positioning and allow clamp the part between the two plates 7, 8. An end stop 72 is provided in the lower cavity 71. This stop is intended to serve for positioning the part 2 in the axial direction thereof. The upper mounting plate 8 comprises a supply stud 82 mounted sliding and opening out into the upper cavity 81. The stud 82 is

  electrically conductive is pushed towards the imprint by a stud spring 83. The stud 82 is electrically connected to a connector 86 to provide an electrical connection. The pad 82 is intended to come into contact with the part 2.

  A lower electrode 61, of general shape

  cylindrical, is fixedly mounted on the lower electrode support 6 and sliding in the lower mounting plate 7. The lower electrode 61 protrudes into the lower cavity 71.

  The lower electrode 61 is carried by a connection support 62 making it possible to mechanically fix the electrode and to connect it electrically to a terminal. Similarly, an upper electrode, of generally cylindrical shape, is fixedly mounted on the upper electrode support 9 and

  sliding in the upper mounting plate 8.

  The upper electrode 95 protrudes into the upper cavity 81. The upper electrode 95 is carried by a connection support 96 making it possible to mechanically fix the electrode 95 and to connect it electrically to a terminal. The electrodes 61, 95 have one end 68, 98 in conical shape opening into

fingerprints 71, 81.

  The mounting plates 7, 8 are crossed by 10 of the respective inlet channels 74, 84 opening into annular chambers 75, 85 to bring an electrolytic liquid near the end 68, 98 of the electrodes 61, 95. The chambers annulars 75, 85 are in communication with the imprints 71, 81 15 by a widening 69, 99 of the guidance of

  electrodes. The electrodes are hollow for channeling the electrolytic liquid to respective drainage channels 67, 97 passing through the electrode supports 6, 9 to the connection supports 62, 96.

  For the operation of the tool 1, the connector 86 is connected to a positive terminal of a generator, not shown, while the terminals of the connection supports 62, 96 are connected to a negative terminal 25 of the generator. Furthermore, the inlet and outlet channels are connected by conduits to a circulation group, not shown, respectively to an outlet and to a return, to

  circulate the electrolyte liquid.

  In the open position, the mounting plates 7, 8 are spaced from each other. The lower electrode support 6 is held in abutment against the lower mounting plate 7 by the base springs 32. In this way, the lower electrode 61 projects into the lower cavity 71, as shown in FIG. 3. Likewise, the upper mounting plate 8 is placed in abutment against the baluster heads. Consequently, the upper electrode 95 is set back with respect to

to the upper imprint 81.

  At this time, the part 2 to be deburred can be placed on the tooling, so that the

  cylindrical surface 22 concides with the lower cavity 71, the end of the part 2 is against the stop 72 and that the bore 21 covers the lower electrode 61 coming into contact with the cylindrical part 15 of said electrode 61.

  The tool is then brought into the closed position

by bringing the plates 3, 4 together.

  In this movement, the upper mounting plate 8 approaches the part so that the stud 82 comes into contact with the part 2. The

  movement of the block is stopped, but the upper mounting plate 8 continues its translation to come into abutment against the part 2, along the upper cavity 81. During this movement, the block spring 83 is compressed.

  The translational movement of the plates continues, while the upper mounting plate 8 is stopped. The upper springs 94 compress ensuring the clamping of the part between the cavities 71, 81. During this movement, the upper electrode 95 is driven by the upper electrode support 9 and leaves the upper cavity 81 to penetrate into the hole 21, to the position shown in

particular in figure 4.

  After the start of tightening of the part 2, the columns 91 come to bear against the lower electrode support 6 and cause its translation on the spacers 31 by compressing the base springs 31. The lower electrode 61 is driven in the same movement and withdraws from hole 21, until

  in the position shown in Figure 4.

  In the closed position, due to the conical shape of the end of the electrodes, a space is created between the electrodes 61, 95 and an edge 23, 24 15 of intersection between the bore and the cylindrical part 22 of the part. This space is the air gap

  necessary for electrochemical operations.

  As soon as the closed position is reached, the electrolytic liquid can be put into circulation by the group. It arrives in the annular chambers, 85 via the inlet channels 74, 84, passes through the widening 79, 99 and enters the bore 21 by completely submerging the air gap. Then, the liquid is evacuated through the hollow of the electrodes and the evacuation channels 67, 97. As soon as the air gap is immersed,

  the electrochemistry operation can begin by circulating a current supplied by the generator between the electrodes 61, 95 and the part 2. This operation electrolytically dissolves the edges 23, 24 by creating a rounding therein.

  At the end of the electrochemical operation, the

  circulation of the electrolytic liquid is stopped and the tool is returned to the open position. The part can be removed and a new cycle started.

Claims (6)

  1. Method for deburring by electrochemistry of a part (2) to be deburred, in which the part (2) is put in place in a tool (1) bearing against stops (71, 81, 72, 61) of positioning, at least one of said stops (61) being retractable, the retractable stop (61) is retracted, at least one electrode (61, 95) is approached near the part (2), characterized in that the one of the stops   retractable (61) at least is one of the electrodes.   2. Deburring tool for the method according to claim 1, the tool (1) comprising: - stops (71, 81, 72, 61) for positioning a part (2) to be deburred, at least one of stops 15 (61) being retractable; - at least one electrochemical electrode (61, 95); characterized in that at least one of the electrodes (61) is a retractable stop.   3. Deburring tool according to claim 2, characterized in that the hardness of the retractable electrode is greater than 55 Hrc (Rockwell hardness). 4. Deburring tools according to   claim 3, characterized in that the retractable electrode (61) is made of metal carbide.   5. Deburring tool according to claim 2, characterized in that the retractable electrode (61) is a cylindrical rod terminated by a narrowed zone (68), the part (2) comprises a bore (21), the part ( 61) abutting against the retractable electrode (61) in the bore (21), the electrode (61) deburring the entrance (23) of the bore (21).   6. Deburring tool according to claim 5, characterized in that the electrode 10 (61, 95) is hollow and channels an electrolytic liquid.