Modern extrusion press for aluminum and its alloys are used with special pockets matrix and feeders, which provide continuous production of the lash welded together at the ends of the profiles of the individual blanks. On saw cutting this continuous hot whip lash cut into a length of 50 and more meters for further straightening and cutting-to-length. Movement and direction of aluminum profiles at the exit of press systems provide modern pollers, are often combined with hot-cutting saws.
Ordinary puller - a pulling device, which directs effluent from the press profile as it moves along the outlet table press for subsequent transfer to a cooling table and further the tenter.
Output table extrusion press
Pullers work on the output table press. For greater certainty of the output section will describe the structure, since some of its sections are named differently. Output table press usually comprises a receiving table, and an output roller conveyor. Reception desk is directly adjacent to the press. He usually has a non-driven rollers, thereon disposed tunnel water or water-air cooling and, usually, stationary hot saw cutting. Just behind the reception desk starting off roller table with driven rollers. The output roller extends parallel to the entire length of the cooling section. Since the output roller table sections traversing system is transmitted to the cooling table, and further - to tenter.
The functions of the puller
Puller extrusion press should perform, how miniumum, the following four functions :
- Adopt and maintain profiles on the receiving table for the entire length of the roller output in each cycle press unattended
- Give a signal to the press to stop pressing, is achieved when the predetermined length of the profile
- To provide a tensile force in accuracy sufficient for, all profiles mnogoochkovoy matrix were identical length
- Promote hot cut saw cutting profile exactly in the space on the outlet roller conveyor, where they will be sent further to the cooling table.
To be able to perform these functions, the puller must be:
- reliable - have a probability of failure of not lower than, than other parts of the press line;
- fast - to perform their tasks and return to the starting position during the technological pause of the press;
- smooth - operate without damage profiles.
Various pullers may differ from each other as intended, and a separate design specifications.
A single puller
Most of the early pollers were single. However, understandably, that a single puller difficult to keep coming back to the starting position on the output table during the waiting time of the press when changing workpiece. The duration of the pause is usually not more than 20 seconds, and the output length of the table, which is necessary to have time to pass Puller, often it is about 50 m. It should be noted, that at an excessively large rate of movement of the puller decreases its reliable operation.
To reduce the non-productive downtime media have been developed various types of double pollers, that provide the, that at the beginning of each pressing cycle one of the pullers is always in the starting position near the press:
- two puller, front and rear, the first transfers the profile to the second during the pressing cycle;
- Parallel Pullers (Twin Pullers), who work in the press cycle turns, that is, through a cycle;
- The combination of the main and auxiliary puller puller. The main puller pulls the profile during the press cycle, and the auxiliary puller drove the profiles already cut more by the output roller conveyor for transfer to a cooling table.
- A combination of a saw-puller and conventional puller. Puller-saw cuts the profile of the track welding and helps ordinary puller spending profile for the output table.
Pullers are moving along the guide rails, which can be placed directly on the output table or next to it.
The following types of puller drives are commonly used:
- a linear motor and
The supply of electric power to the puller
The energy to drive the puller arms (and the hot-cut saw, when it is installed on one of the pullers) can be supplied:
- on cable suspension,
- on the supply rails or
- in the form of compressed air to the air cylinders, are charged after each working cycle.
Types of seizures and their actuators
Puller grips can be in the form of a vise or consist of several segments (fingers). The grippers are opened and closed by pneumatic cylinder, springs, hydraulic cylinders or linear electric actuators.
Pullers with servo-drives
Modern pullers require precise positioning on the output table and the rapid discharge of their functions. The latest development in the development of puller systems for extrusion presses for aluminum was the use of servo drives on them to drive various devices .
Leading manufacturers of pressure equipment already offer these pullers. In figures 1 and 2 shows the different types of pollers Tecalex using servo drives :
- a single puller with a capture servo (hereinafter - "puller") and
- puller with built-in hot cutting saw (hereinafter referred to as "puller-saw") with grab servo drives, moving the saw blade and saw rotation.
Work pollers system with servo-drives
on pullerah, who work for servo, Each actuator is controlled by its own controller. The control cabinet of programmable logic controllers (PLC) is connected to the servo drives via busbars on the monorail, by which drive pullers. specified parameters, for example, speed and acceleration are transmitted through the controller to the servo control system.
EXAMPLE pollers system operation - without puller puller with saws and saw -Shows, What challenges must perform pullers when processing profiles, leaving the press .
A puller without a saw works mainly within the outlet roller table (figure 3). When the puller reaches the end of the profile roller conveyor, puller-saw arrives at the last traces of welding, which was formed when stopping the press for loading a new workpiece. The puller saw cuts the profile exactly along the weld track (figure 4).
After cutting the profile puller reaches his roller conveyor for transferring the cooling table, and further stretching machine. Puller-saw pulls along the following profile of the output table so far, until a puller without a saw returns and takes it from him (picture 5). Then puller continues to pull the profile of roller conveyor, and the puller saw returns to the press and waits for the next profile cut (picture 6).
The advantages of servo
Servo systems technology for compressing lines pollers aluminum profile has the following advantages as compared to conventional drive systems, most often, hydraulic :
- Servo system provides a more precise execution of a predetermined movement cycle components pollers.
- movement cycles of various actuators can be accurately monitored and then sync within the overall system pollers.
- Servo have increased reliability.
- Maintenance of servo systems, less time-consuming.
- Elimination of hydraulic oil increases fire safety equipment.
- In view of the life cycle of servos are the best investment performance in comparison with other, lower costs drive, for example, hydraulic.
- Jürgen Sturm and Jaume Amoros, Servo-Drive Applications in Aluminum Profile
Extrusion Equipment, Aluminium Extrusion Technology Seminar, Chicago, 2016