The mechanical machining of flat workpieces in the process of automatic welding

 

(57) Abstract:

The invention can be used in the machining of difficult materials. Rotating the cutting tool is placed on the distance from the electrode. The angle of the cutting edge of the tool to the weld surface is chosen from the condition of ensuring the ingress of swarf in the area of the welding bath. The cutting speed set taking into account the trajectory of the chips. Prevent the departure of chip area weld pool through the gutter. The method provides the efficiency of the process by eliminating the release of metal in the prayers chips when machining the deposited layer. 2 Il.

The invention relates to mechanical engineering and can be used in the manufacture or repair of machine parts and tools in the process of automatic welding, mostly hard-to-cut materials.

A known method of mechanical processing of materials [1] heated in the cutting zone, carried out by an electric arc submerged arc welding. However, the known method does not involve the combining of the operations of heating with the coating does not provide a non-waste production.

It may be noted the following deficiency:

- chips goes to waste, and mixed with a flux when welding.

The present invention is to increase process efficiency by eliminating output of the metal in the prayers chips when machining the deposited layer.

This object is achieved in that in the method of machining of flat workpieces in the process of automatic welding processing weld surfaces are rotating cutting tool and the workpiece performs translational motion relative to the electrode and the machining tool. Cutting edge features at an angle to the weld surface processed the La shall be determined in accordance with the following expression:

< / BR>
where B is the width of the deposited layer;

l is the distance from the cutting tool to the area of the welding bath.

When the cutting speed set so that the length of the arc trajectory chip corresponded to the distance from the cutting tool to the area of the welding bath. The speed value is determined from the expression:

< / BR>
where mp- the mass of the element chip;

mf, Rfrespectively the mass and the radius of the cutting tool;

t - depth of cut.

During processing, use the groove, preventing the departure of the chip area of the welding bath.

The starting point of the cut is determined from the reliable cutting tool with the highest resistance. Reliability hitting the higher, the lower the hardness at the point to start cutting. Hardness nonlinear temperature dependent ceteris paribus. Therefore, very low values of hardness can be achieved only at temperatures close to the melting point. Metal processing with such a temperature significantly reduces tool life. Thus, there is an interval of values of hardness of the metal in the starting point of cutting, providing the highest resistance in the cutting is done by plotting the distribution of hardness along the axis of the cladding under specific conditions. To do this, define a computational or experimental method the temperature distribution along the axis of the cladding for the tin bath in quasi-stationary mode. For the sample deposited under specific conditions determine experimentally the temperature Tocorresponding to the above hardness of the weld metal. Point cutting is the intersection of the isotherm surfacing with temperature Towith the axis of the welding parts. Measured or calculated distance l from the arc to the point of cutting.

The essential features of the claimed technical solution are:

- perform automatic arc welding;

- simultaneously with the welding handle cutting tool;

- cutting tool rotates;

the item performs translational motion.

The essential features of the technical solutions with the novelty are:

- cutting edge of the tool is placed at an angle so that the direction of the vanishing chip led to the ingress of swarf in the area of the welding bath;

- the angle of the cutting edge is determined from the above expressions (1);

the cutting speed when processing set so that the second bath;

- the value of cutting speed is determined from the above expressions (2);

- use the gutter, preventing the departure of the chip area of the welding bath.

Mathematical expression (2) is derived from the flight conditions of the chip. Considering the differential equation flight shavings under the action of the constant force of gravity we find that the range of the chip depends on the initial speed and angle of departure :

< / BR>
Hence, given the condition that the tool rotates and depending on the weight of the chip and tool deduced that the value of cutting speed is determined in accordance with the following expression:

< / BR>
The angle depends on the depth of cut, since the ejection of the chips occurs under the action of a force directed along the tangent, perpendicular to the radius of the cutting tool. Therefore, its value is defined as:

< / BR>
The final expression for determining the cutting speed looks as follows:

< / BR>
The invention is illustrated by drawings (Fig. 1 and 2), which shows a top view (Fig. 1) method of machining of flat workpieces in the process of automatic welding section a-a (Fig. 2). The drawing shows a cutting ins 4, the electrode 5 and surfaced item 6, and the angle of inclination of the cutting edge and the width of the deposited bead B.

The method is implemented as follows: on the workpiece, identical surfaced items, begin experienced the cladding modes that are already assigned. After the establishment of a stationary process the welding stop and fix the position of the crystallization isotherms for the known thermal conductivity and modes of deposition by the equation layer temperature limit state from a concentrated source in the moving coordinates. The sample overlay placed in an oven to determine the hardness of surfacing at different temperatures. Find the temperature corresponding to the interval of the hardness of 18 to 28 HRCE. Using the formulas from the source [4] , using the obtained values of thermal diffusivity, find the distance to the point with this hardness from the heat source. Make the installation setup. Select a cutting tool with an angle of inclination of the cutting edge defined by the formula (1). Set the depth of cut and having the data of the mass and radius of the cutting tool, the mass of the element chip for a given cutting tool and the cutting depth defined by the cutting speed according to the formula (2). Installed gutter, prepyatstvuyushchee movement, details of the progressive movement.

As an example, we describe a method of machining when arc welding wire SV 08G2S on the workpiece material: steel 45 on the cladding speed Vn= 10 m/h and the feed speed VE= 184 m/hour. Experimentally determined, in these modes, the average height of the surfacing is 3.5 mm, the width of the rollers 9.5 mm, is determined Experimentally that the hardness of 20 HRCEthe surfacing material reaches at 700oC, the length of the rear part of the tub when these modes of deposition was at the open arc welding 16 mm at steady-state mode. The calculated values of thermal diffusivity was performed according to known mathematical expression

< / BR>
where x is the distance from the heat source to the crystallization isotherms (equal to 16 mm);

T - temperature melting material deposition (1300oC);

- thermal conductivity of the material deposition (0,075 W/cmoC);

Vn- speed welding.

After substitution of numerical values and calculation results have determined that thermal diffusivity = 0.5 cm2/s

Counting on the same expression values of T2for different x-coordinates when thermal diffusivity = 0.5 cm2

Thus, we have determined the point of incision, it is separated from the electrode at a distance of 53 mm cutting Depth was 0.5, the mass of the element chip was determined experimentally, it amounted to 0.5 g, the weight of the cutting tool 800 g, the radius of 100 mm

Cutting speed:

< / BR>
The angle of the cutting edge was:

< / BR>
It was established experimentally that when data values of cutting speed and angle of the cutting edge and through the chute, preventing the departure of chip area weld pool more than 90% of the chips got in the zone of the welding bath and was melted in it due to the accumulated heat of the welding bath. Processing led carbide tool.

In identical conditions were processed surfacing at the point of incision with temperatures of 600, 800, 1000oC and hardness respectively 28 HRCE, 18 HRCEand less. In all cases, the tool wear was more than a hardness of 20 HRCEwith the temperature of the processed metal 700oC. This confirms the correct hardness of the weld metal at the point of incision for low-alloy steels.

Technical appraisal and economic benefits in comparison with aniki surfacing in the tub;

- increases tool life by reducing the mechanical strength cutting metal;

the method allows the processing of weld metal with high hardness.

Literature

1. Auth. St. N 421429, B 23 B 1/00, 1972.

2. Auth.St. N 1098664, B 23 B 1/00, 1984.

3. Rybalkin N. N. The processes of heat distribution in arc welding. Part 1. M-Leningrad: an SSSR, 1947, - 271 S.

4. Auth. St. N 1146166, B 23 K 28/00, 1982.

The mechanical machining of flat workpieces in the process of automatic welding, which uses a rotating cutting tool, have it at a distance from the electrode is determined by the cooling time of the deposited layer to the optimum cutting temperature, characterized in that the conditions ensuring the ingress of swarf in the area of weld pool choose the angle of the cutting edge of the tool to the weld surface in accordance with the expression

< / BR>
where B is the width of the deposited layer;

l is the distance from the cutting tool to the zone of the weld pool,

as well as the value of the cutting speed V in accordance with the expression

< / BR>
where mp- the mass of the element chip;

mfand Rf- sootvetstvenno the zone of the weld pool through the gutter.

 

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FIELD: mechanical engineering.

SUBSTANCE: invention relates to machining of cellular fillers on five-coordinate numerically-controlled machine tools. Method comes to setting plane of rotation cutting tool at angle to surface to be machined. To improve accuracy owing to corresponding space orientation of cutting tool in process of machining of machining, alignment of axis of cutting tool with plane determined by straight line connecting point of touch with following support point and vector of normal to machined surface are provided by additionally turning axis of cutting tool around vector of its linear displacement. Disk cutter can be used as cutting tool.

EFFECT: improved accuracy of machining.

2 cl, 3 dwg

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