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Chain Draw Bench Machine
The machine is suitable for drawing Metal tubes and bars. Metal material is forced deformed by drawing dies,  get improvement on surface hardness, elasticity, tensile strength and surface quality.During the work process, the machine is with low vibration,
Description
I. Equipment specifications
1. Design basis and technical parameters
1.1 Service conditions
(1.)440V± 10% (three phase), 60Hz
(2.)Working pressure of compressed air P =0.4 ~0.6 MPa;
(3.)  Room temperature: 0 ~ 38℃
(4.)Seismic fortification intensity: 7 degrees
1.2 technical parameters
SerialNo. Project name Unit Parameters
1 Rated drawing force T 40
2 Range of drawing speed m/min 1-20
3 Speed of rated drawing force m/min 16
4 Effective length of finished product M 6
5 Drawing diameter MM 12-80
6 Main frame power KW Z4-132KW/1000r/min
7 Sprocket parameters Pitch mm 127
Number of teeth Z 15
8 Main reduction gearbox   ZL130
9 Return speed of drawing carriage m/min 50
10 Slowly approaching speed of carriage m/min 0-5
11 Feeding speed m/min 30
12 Feeding rack M 8
13 Lubrication system   Feature lubricating device; the lubricating oil can be recycled after filtered.
14 Unit capacity KW ≈145
15 Power supply   440V±10% (three phase), 60Hz±2Hz
16 Drawing material   Brass rod,bar
17 Operation elevation mm 950
18 Consumption of compressed air M³/ h 0.4
19 Number of drawing pc 1
20 Unit dimension (length * width * height) m About 19×4×1.8 (subject to the final design)
21 Total weight T About 40 (subject to the final design)
2. Equipment features
The equipment is a single-chain mechanical drawing machine, and the main drive motor adopts DC speed adjusting device. The overall design fully considers the energy conservation, stability, efficiency, noise reduction and so on. The system realizes slow approaching using the drawing carriage, engaged at low rate and drew at high rate. During the auxiliary time, the main frame stops running and is in standby state with low power, which reduces wear caused by mechanical transmission and energy consumption caused by motor running. The operation mode of drawing process is as follows: when the system identifies (load feedback) drawing ends, the main frame stops immediately; when the carriage returns to clamp materials with a certain distance from the drawing die holder, the inverter controls the carriage reduction through the detection by photoelectric sensor, and makes it slowly close to the drawing die holder, and then the main motor recovers operation and is at the low rate. When the carriage jaw clamps a workpiece and the hook is hung on the main chain, the main motor start to speed up, and perform drawing according to the preset drawing speed, so as to achieve slow approaching, low-speed engagement andhigh-speed drawing.
2.1 Description of the machine operation: blank is put into the trough from the feeding rack by feeding device --- blank is pushed to the front side of die hole by cylinder --- blank is clamped by the oil cylinders on both sides --- blank is pushed into the die hole by the oil cylinders --- blank is clamped by the carriage for drawing --- receiving arms stretch out in turn when drawing --- blank is loosened by the carriage jaws and rolls into the receiving device --- carriage returns --- preparation for receiving material --- repeat the above steps.
2.2 Scheme
1. Features of ZSY reduction gearbox: high hardness of tooth surface, high transmission load, high transmission efficiency, more suitable for largetorque and power transmission, with a safety coefficient of 2.5 times. Compared with ZQ reduction gearbox, ZSY reduction gearbox is more stable, easy to maintain and holds longer service life.
2. Die sleeve is installed on the drawing die holder. The die can be directly replaced when drawing different specifications and shapes of blanks. Size of the die sleeve will be provided then.
3. When the rod diameter is less than 30mm, its use on the coil pusher machine will lead to increase bend probability, due to increased area reduction. If you want to reduce bend probability, it is necessary to reduce area reduction, but it will also reduce efficiency (because of the need of multiple drawing). The quality and efficiency of drawing can be improved using off-line head-shrink machine.
4. The automatic feeding device requires the straightness of 30mm/m for incoming material, and not more than 120mm in total length of 5m.
3. Components
This device is composed of mechanical part (main frame, auxiliary), electric control system and hydraulic system, etc.
3.1 Mechanical part
Mechanical part is composed of main drive, lathe and lathe bracket, main chain wheel, drawing die holder, feeding rack, feeding device, receiving device, drawing carriage and so on.
3.1.1 Main drive
It provides the power for the drawing chain. The initial power is provided by DC motor and output through the gearbox, to realize deceleration, thereby reducing the rotational speed and expanding the output torque of the motor. The torque is output through the main reduction gearbox to drive the main chain wheel; the chain wheel drives the drawing chain, so as to meet the need of drawing force. This unit is composed of motor base, DC motor, reduction gearbox and chain wheel mechanism, connected by LX elastic pin coupling. The elastic pin coupling can transmit torque and achieve overload protection of reduction gearbox. The main chain will follow the chain wheel in case of load, which will destruct the chain wheel seat. A protection shovel plate shall be mounted below the main chain wheel seat to ensure that the main chain separate from the main chain wheel. The main chain wheel is made of 50Mn casting blank and subject to forging, finish turning, wire cutting for teeth, overall quenching and tempering and hardening of teeth surface, with the hardness of HRC52-55.
 
3.1.2 Lathe and lathe bracket
Lathe acts as the track of drawing carriage and the carrier of main chain, which can offset some tilting force of drawing die holder. The lathe is a box girder type structure, and the chain is made of 65Mn material. Overall heat treatment shall be conducted. The lathe is welded by Q235 steel plate. Annealing shall be conducted after welding to remove stress, in order to prevent subsequent processing deformation, and then finishing matching shall be conducted. The lathe bracket is at the bottom of lathe, which is a group of loose moving rollers for main chain, used to reduce friction consumption of main chain transmission. An oil trough is mounted beneath the lathe to achieve self-lubrication of main chain. The lubricating oil recycling tank is used to recover the lubricating oil which flows back to the oil tank after filtered for recycling. One side of the lathe is the drive chain of carriage. The main chain guide plate is installed on the lathe, to prevent deviation of main chain. Forced decoupling plate is installed at the end of lathe.
 
3.1.3 Main chain
It mainly realizes drawing of main executive components. It is driven by the chain wheel on the main chain wheel seat, supported by rollers at the loose edge and liner plate of lathe at the tight edge, and mounted passively on the drawing die holder. When the drawing carriage approaches to the drawing die seat, the carriage is inflated and the cylinder pushes the jaw for clamping and then pushes the tiger hook to hang in a joint pin shaft for drawing. Main chain is the key component of drawing machine, so high-quality materials and overall quenching process shall be selected.
uChain plate: double-row straight chain, quenching
uChain axis: material 40Cr, quenched-tempered heat treatment HB = 350 - 320
uTension way: control the tension of main chain by regulating the screw
3.1.4 Drawing die holder
Stress of drawing machine concentrates on the drawing die holder, so welding of drawing die holder follows the welding technology of heavy equipment, and then annealing is conducted after welding to remove stress before conducting follow-up processing. Drawing die holder is mainly to achieve installation of external dies and determine the diameter of pipes. The main chain driven wheel and the carriage driven wheel are mounted on the drawing die holder. The die sleeve is designed to sphere and fixed on the template, which is convenient to adjust the coil during drawing and improve the straightness of drawing finished products. The driven wheel is arranged on the front end of the die holder, supported by bearing pedestals at both sides. The bearing pedestals are pulled by two screws. The tension of main chain can be controlled by regulating the screw.
 
3.1.5 Carriage drive
It mainly realizes drawing of round-trip driving mechanisms on carriage, driven by AC motor and suitable for frequent start and reversible operation. When the carriage has a distance from the drawing die holder, it shall be decelerated through detection by photoelectric sensor to 0-5 m/min (adjustable) to slowly approach to the drawing die holder, so as to reduce its inertia impact on the die holder and effectively reduce the noise. Assemblies include pulley, steel wire rope set, speed reducer and elastic pin coupling. The steel wire rope set is arranged within the lateral channel steel of the lathe. The main drive shaft is mounted on the lathe. The driven shaft set is mounted on the end of drawing die holder.
3.1.6 Receiving and unloading device
  When drawing is conducted, the cylinder drives the receiving arm to rotate 90º to the beneath of workpiece and prepare to pick up material after the receiving sensor on the lathe detects the receiving signal. When the drawing is finished, the workpiece rolls to the receiving box on the other side of the lathe through the receiving arm ramp. Soft materials are installed on the receiving arm and within the receiving box to avoid surface damage. The receiving arm will return after the receiving action is completed, waiting for the next receiving.
3.1.7 Drawing carriage
Drawing carriage is composed of bottom plate, clamp jaw, gas tank, movable head, cylinder, air nozzle, a tail hook and travelling wheel, etc. The clamp is a group of combined four-rod mechanism, mounted on the bottom plate by using the pin shaft. The tail hook is installed on the movable head. When the carriage moves to the drawing die holder and the jaw reaches the blank head in the die hole, the clamp is driven pneumatically and the tail hook tangles a pin shaft of the main chain. The main chain in motion can pull hook tail and movable head to start drawing. The counterforce and drawing force will disappear when the drawing is finished. The tail hook will decouple automatically and is in a suspended state. When the tail hook can not be ended and timely decoupled in the process of drawing, the carriage will be brought to the end of lathe; two wing plates on the hook tail will contact the decoupling plate, so as to raise the bevel of tail hook and force decoupling.
 
4. Electronic Control System
The main chain of drawing machine is driven by DC motor. PAKER590 series full digital DC speed regulating device is used as the speed regulator, and the encoder or tachometer generator is used for speed feedback, thereby forming a speed closed-loop regulation system. S7-200 SIEMENS series PLC system is used to complete the logic control of drawing machine, and SIMATIC HMI is used as the equipment man-machine dialogue, used to monitor the production process in real time.
4.1 Control and equipment function
The system is designed from the point of view of energy saving, reducing mechanicwear, prolonging the service life and enhancing the system stability. The main drive is driven by a DC motor. Under the automatical state, the main motor start running at low speed when the drawing carriage approaches to the drawing die holder about one meter.The main motor begins to speed up and start drawing according to the preset drawing speed when the carriage jaw clamp the workpiece and tiger hook is hung in the main chain.PLC will issued stop instruction to the DC speed regulating device after determine that the drawing of a finished product is finished according to the load current, and then the main motor stops running based on inertia. PLC will control the main motor to start running again when the carriage approaches to the drawing die holder once again and photoelectric sensor detects the signal. In case of product breaking andfalling off during drawing, the main frame will automatically stop running, which effectively avoids possible equipment damage. The lubrication system starts automatically during drawing, and its AC motors are protected by thermal overload relay.
A small operation platform is mounted on the side of the drawing die holder, equipped with various auxiliary operation buttons such as manual/automatic buttons, buttons for start/stop of main frame, delivery and feeding, start and stop of lubrication pump, point forward point back of carriage. The master operational console is equipped with a SIEMENS HMI, which shows the drawing force, drawing speed, running state of each mechanism, output, fault alarm and so on.
In the case of feeding by device, blank is clamped by the cylinders on both sides, and then the rear cylinder moves forward to push the blank into the die hole when feeding conditions are reached.
Front side of the main control cabinet is equipped with "centralized - machine side" selection switch, start/stop button and emergency shutdown button, necessary signal lamps and instruments (such as signal lamps for ready, running and fault, voltage meter, current meter and tachometer etc.). The cooling fan is mounted in the cabinet, achieving synchronous operation with the speed regulating device.