Such tubes have highly precise sizes, wall thickness, outer and inner diameters, high quality of outer and inner surfaces and favorable metal structure.
The tubes are typically used in space and aircraft engineering, shipbuilding, petrochemical and chemical industries, and other sectors of machinery building.
CRTM 350-8 mill is designed for front charging of a billet with its feeding to the deformation zone by pressing it to the end, with front drive location of left (or right) design.
Rolling process is carried out by reciprocating grooves with a variable profile on a cone-shaped or curved mandrel fixed in axial direction. When rolls approach their end positions a tube is released from the grooves. Feeding and turning of the tube is performed in end rear and front positions of the stand.
The equipment consists of a set of machines that carries out the major operations in the course of the tube production:
- stand drive;
- three-roll working stand;
- leverage;
- feed area equipment;
- intermediate chuck;
- front chuck;
- charging table;
- finished tubes receiving table;
- oil and grease lubrication systems;
- safety devices.
The three-roll working stand is designed for production of high-quality tubes of cylindrical cross-section with reduction of the billet initial wall thickness variation. The stand consists of a movable power housing designed for reception of rolling forces and mutual alignment of the grooves in the course of rolling and a movable cassette with working rolls.
On either side of the stand there are sprayers with nozzles feeding lubricant coolant into the deformation zone. Lubricant coolant supply is carried out by a stand-alone pump plant.
The feeding mechanism performs pulse feeding of the tube in the course of the cassette passing through the end positions (roll gap opening time) and accelerated retraction of the billet chuck in the course of the mill reloading. Billet pulse feed and chuck accelerated retraction are performed by servomotors which operation mode is set by an electric control system.
The rod fixation mechanism performs pulse turning of the rod in the course of the cassette passing through the end positions (roll gap opening time) and prevents the rod axial displacement in the course of rolling. The mechanism fixes the mandrel in a set position within the deformation zone through clamping of the rod end. For correct positioning of the mandrel in the deformation zone the rod fixation mechanism is provided with axial displacement actuated by the mechanism drive.
Guides with rest devices and the billet chuck installed between the rod fixation mechanism and the feeding mechanism are used for alignment of the billet chuck and the rest devices, as well as for centering of feed screws with an output shaft of the feeding mechanism. The movable rest devices installed in the feeding section are kept in pairs by telescopic pull rods.
The billet chuck is designed for feeding of the billet into the deformation zone. The chuck consists of a frame with spindle installed on bogies. The chuck movement is actuated by two screws from the feeding mechanism.
The charging table is designed for receiving of billets, their arranging in one row and transferring to the rolling line item by item. The charging table consists of a receiving skid with a dozer, a roller table, an ejector and a trolley with a pusher.
The finished tube receiving table is designed for receiving and collecting of finished tubes. Then the tubes are transferred to storage areas by a crane without stopping the mill.
TECHNICAL SPECIFICATIONS
|
№ |
Item |
UM |
Index |
|---|---|---|---|
|
1 |
Max billet outer diameter with plus tolerance, not more |
mm |
360 |
|
2 |
Billet thickness |
mm |
5-40 |
|
3 |
Billet length |
m |
2,5-8 |
|
4 |
Tolerance for billet outer diameter |
% |
±1.0 |
|
5 |
Tolerance for billet wall thickness, not more |
% |
±12.5 |
|
6 |
Billet camber |
mm/m |
2 |
|
7 |
Finished tube outer diameter |
mm |
140-325 |
|
8 |
Finished tube wall thickness |
mm |
3-32 |
|
9 |
Finished tube maximum length |
m |
25 |
|
10 |
Finished tube surface cleanliness Ra |
μm |
0,8 |
|
11 |
Tolerance for finished tube wall thickness, not more |
% |
±6,0 |
|
12 |
Tolerance for finished tube outer diameter |
mm % |
±0.7 ± 0,2-0,3 |
|
13 |
Power housing stroke length Work cassette stroke length |
mm |
1600-1700 1100 |
|
14 |
Rolling groove working zone |
mm |
950 |
|
15 |
Stand maximum speed, not more |
dbl. stroke/min |
45 |
|
15.1 |
Stand rolling speed |
dbl. stroke/min |
30 |
|
16 |
Feeding value |
mm |
2-25 |
|
17 |
Feeds quantity per cycle |
|
2 |
|
18 |
Turning angle, not more |
° |
35 |
|
19 |
Turns quantity per cycle |
|
2 |
Advantages
1. High accuracy and quality of rolled tubes.
2. Wide technological capabilities: rolling with double turn and feed, possibility to change feed and turn rates without stopping the mill..
3. Transmission shafts are excluded from the equipment. It increases mill reliability and operation life.
4. Tube deformation with max coincident of effective stand diameter with effective diameter of rolling schedule due to adjustment of the lever drive system.
5. High reliability and service life of the mill mechanisms due to use of time-proved design.
6. Favorable working conditions in the course of equipment operation:
- low noise and vibration level;
- reliable safety devices;
- exhaust system in the working area.