RU2569683C2 - Method of formation of brushes profile of dc electrical machines - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: method of formation of brushes profile of DC electrical machines means that one or several new brushes are taken and installed on table of wire-cutout electroerosion machine. According to rated radius of required commutator the drawing of the brush contour is determined, and obtained profile is set in programming system of NC control, that generates (determines) machining modes: pulse width, pause between pulses, main flowing current, voltage of spark gap, generator power source voltage, high level of machining speed, wire tension, speed of wire winding. Then machining program is run in NC control, and the brush profile is cut by electric spark discharges flowing through wire. After reception of the necessary profile the package or brush is installed on the commutator.

EFFECT: reduced time for brush profile forming.

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Description

The invention relates to the field of mechanical engineering, in particular to the manufacture and repair of electric DC machines (MPT).

Scope - enterprises manufacturing and repairing electric DC machines.

It is known that the formation of a brush profile corresponding to the profile of the working surface of the collector of a direct current machine (MPT) is currently carried out directly on the surface of the collector by pressing a spring-loaded brush on a rotating collector. Currently, in the repair production under the conditions of locomotive repair depots, the accelerated formation of the brush profile on the collector is carried out through the use of a glass abrasive cloth applied to the collector surface and facing the brushes with the working side. The brush is pressed to the working surface of the glass abrasive blade, after which it is rubbed, moving the blade back and forth, at normal (30-50 N) spring pressure on the brushes [Gemke R.G. Faults of electric machines / R.G. Gemke. - L .: Energoatomizdat, 1989 .-- 336 p. (p. 142)].

The disadvantage of this method of forming a brush profile is:

- the process of direct grinding of the brush on the MPT collector is inefficient in time;

- large losses of brush material (at least 5-15% of the brush material of the total mass of the brush is removed as wear products);

- a large amount of brush material clogs the inter-lamellar gaps, which in turn entails subsequent blowing of the collector with compressed air;

- the use of an abrasive cloth to reduce the grinding time of the brush to the collector masks the surface of the brush with solid abrasive particles, which leads to increased wear of both the brush and the collector during MPT operation.

The objective of the invention is to reduce the time of formation of the profile of the brushes corresponding to the profile of the collector in the process of their manufacture or repair before commissioning MPT in operation.

The essence of the invention lies in the formation of the working profile of the brush, corresponding to the profile of the collector MPT, by EDM cutting wire on a numerically controlled machine.

This technical result is achieved by the fact that several new brushes, for example 2 to 8, are installed in a package on a table of a wire-cutting machine. According to the nominal radius of the desired collector, a drawing of the brush profile is determined and the resulting profile is set in the programming system of the numerical control device (CNC), for example, HeartNC UTY. It is possible to process both the profile of the brush pack and one brush. The CNC generates (determines) the processing modes: pulse length, pause length between pulses, main current current, spark gap voltage, voltage of the generator power supply, upper limit of the processing speed, amount of wire tension, wire winding speed. Next, run the processing program in the CNC device and cut the profile of the brush (package of brushes) with electric spark discharges flowing through the wire. After obtaining the necessary profile, the bag or brush is installed on the collector in the traditional way.

Figure 1 presents the table of the EDM SODICK VZ300L with a fixed brush.

Figure 2 shows the position of the wire before touching the brushes.

Figure 3 presents the menu of the automatic rotation of the coordinate system (“U-turn SC AUTO") in the "MANUAL" mode.

Figure 4 presents the menu of the function of touching the face ("TOUCH FACE") in the "MANUAL" mode.

5 is a drawing of a brush profile defined in the editor "HeartNC UTY".

Figure 6 presents the selection of the path of the wire in the menu "WIRE CUT DEFS".

Figure 7 presents the table of definition of the parameters "DEFINITION PARAMETERS" (OPEN).

On Fig presents a table of mode selection.

Consider a specific example of the implementation of the proposed method for forming a brush profile.

We take one new brush (Fig. 1) or a package of new brushes 1 (GOST 12232-89) and install 2 wire-cutting machines, for example, SODICK VZ300L on the table. Using clamp 3 and screw 4, we fix the brush on the table 2 of the machine.

Determine the position of the brush 1 on the table of the machine (Figure 2). In order not to align the brush on the machine table with an indicator, we expand the coordinate system along one of the brush faces. To do this, in the “MANUAL” mode, select the automatic coordinate rotation function “SC AUTO REVERSE” (Figure 3). In the "DIRECTION ST" field, indicate the direction in which the wire should touch the brush. In our case, “Y-”. In the "DISTANCE TO OTHER POINTS" field indicate the most distant point (for example, 28 mm with a brush length of 30 mm). After pressing the “ENTER” key, the machine automatically expands the coordinate system along the brush edge. Next, we determine the position of the brush faces relative to the coordinate system of the machine. To do this, in the "MANUAL" mode, select the "TOUCH FACE" function (Figure 4). In the “AXIS AND DIRECTION” field, indicate “Y-”, in the “ASSIGN 0” field, select “ON”. After pressing the “ENTER” key located on the CNC stand, the wire automatically touches the brush edge, the CNC of the machine “remembers” this coordinate and assigns it a “zero value” in order to accurately determine the position of the brush on the table. Thus, the position of the edges of the brush on the machine is automatically adjusted relative to the coordinate system of the machine by touching the wire 5.

We determine the brush profile according to the nominal radius of the collector, for example, R = 330 mm, etc. We set the profile drawing of the brush 6 (Figure 5) in the programming system "HeartNC" (UTY) of the CNC device.

Next, proceed to the selection of the trajectory of movement. In the menu "WIRE CUT DEFS" (Fig.6), select the type of processing path "OPEN" (open circuit). At the same time, a table for determining the parameters "DEFINITION PARAMETERS" (OPEN) appears (Fig.7). In the table, we set the length of the starting cut-in “Starting Cut Length” - 7 mm. At the starting insert, the machine underestimates the processing modes to reduce the likelihood of wire breakage. The direction of the wire offset from the “Offset Direction” circuit - set it to “left” to get the required size.

Confirm the selected parameters with the "OK" button (Fig.7). An image of the mode selection table appears on the monitor (Fig. 8). In it, we set the diameter of the wire that is installed on the machine. In a specific implementation example, 0.25 mm, the workpiece material is graphite, the workpiece thickness is 10 mm, the nozzle position is “Open-U”, the number of passes is 2. We confirm the selected parameters with the “SEARCH” button.

We indicate with the cursor the contour that needs to be cut, and set the starting point, from which we cut the brush profile with electric spark discharges flowing through the wire. Click the “Gen NC Data” button. After that, we type the name of the program: for example, “SCHOTKA”, under which it will be stored on the hard drive. The CNC device automatically generates a program and determines the optimal cutting conditions: pulse length (ON), pause between pulses (OFF), main current (IP), spark gap voltage (SV), generator power supply voltage (V), upper speed limit processing (SF), wire tension (WT), wire winding speed (WS), based on the entered data. According to the generated program, the brush profile is cut by electric spark discharges flowing through the wire and a finished brush profile is obtained.

The technical effect of the invention is as follows:

- in reducing the time of formation of the profile of the brush;

- in the absence of loss of brush material, since part of the new brush is removed not in the form of wear products, but in the form of an integral element that can be reused;

- since the brush profile is not formed on the collector, the brush material does not clog the inter-lamellar gaps, as a result of which the collector is not purged with compressed air;

- the surface of the finished brush is not sharpened with solid abrasive particles, since the abrasive cloth was not used at all, which leads to reduced wear of both the brush and the collector during MPT operation.

Claims (1)

The method of forming the brush profile of electric DC machines is that one or more new brushes are installed in a package on a table of a wire-cutting machine, a drawing of a brush profile is determined in the numerical control device, which is determined by the nominal radius of the desired collector, then numerical program control generates processing modes of the basic quantities: pulse length, pause length between pulses, main current current, spark gap voltage, voltage of the power source iterator, the upper limit of the processing speed, the value of the wire tension, the speed of the wire winding, after which the processing program is started in the numerical control device and the brush profile is cut by electric spark discharges flowing through the wire, after receiving the necessary brush profile it is installed on the collector.

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