SERVO DRIVE SYSTEM ADVANTAGES IN EXTRUSION PRESS FEEDING

SERVO DRIVE SYSTEM ADVANTAGES IN EXTRUSION PRESS FEEDING Date: 29/05/2015 INDEX 1.- TECALEX PRESENTATION 3 2.- INTRODUCTION 4 2.- WORKING PRINCI...
23 downloads 0 Views 948KB Size
SERVO DRIVE SYSTEM ADVANTAGES IN EXTRUSION PRESS FEEDING Date: 29/05/2015

INDEX 1.- TECALEX PRESENTATION

3

2.- INTRODUCTION

4

2.- WORKING PRINCIPLES OF SERVO DRIVE SYSTEMS

5

3.- HOT BILLET SAW OPERATION

6

4.- PRESS FEEDER OPERATION

7

5.- SERVO DRIVE ADVANTAGES

9

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



2

1.- TECALEX PRESENTATION

In 1965 TECALEX started its activity in the aluminium technology and offers today a full range of cutting-edge production lines for aluminium profiles to be used in building systems or technical applications. The company has been able to successfully place itself in many international markets in recent years. Current references over the past 3 years can be found around the globe, including England, Poland and the Middle East. In North America TECALEX has already added three modern press lines Numerous subsequent orders of complete extrusion plants from regular customers secure TECALEX today an impressive order schedule for 2015 and beyond. Our activities include complete project management, providing advice on the development of the “Business Plan” sales, finance, design, innovation, engineering, delivery, installation, commissioning and training which is supported by our highly qualified after sales service. We focus on custom projects which include turnkey for new plants, modernization of existing production lines or special engineering designs taking into account the latest standards for health and safety in aluminium extrusion plants according to EN-14656.

We are your partner for aluminium technology

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



3

2.- INTRODUCTION Modern aluminium extrusion industry faces increasing demands for high-precision profiles and sections. Not only are designs becoming more and more complex, with dimensions specified down to micrometre levels, but also these profiles frequently have to be produced in very small batches. The automotive and industrial sectors are two profile consumer groups where the demands for these requirements are common. Such precision manufacturing requires specific design of the press feeding, extrusion press and run-out systems. Press feeder design and management principles that allow for precise heating, cutting and loading especially of two piece billets onto the extrusion axis are highly important. Within the Tecalex press feeding servo drives are used for the log loading system (pusher of the log loader table), the hot billet saw (saw motor and positioning of the log to cutting length) and the press feeder providing very precise and repeatable control of position and velocity. Its various feedback parameters monitor the feeding process and detect any abnormalities before they become major problems. The following figure shows a total use of 6 servo drive systems within the Tecalex press feeding.

Fig. 1: Servo Drive Press Feeding Overview

The log pusher of the log loading table is servo driven (servo 1) and works together with the hot billet saw gauge (servo 2). The saw disc drive is equipped with another servo (servo 3). The press feeder uses 3 more servos for the linear movement, up- and down movement of the billet shelf and length adaption of the billet shelf in function of the loaded billet length according to the extrusion press requirement. The following chapters will explain the different process sequences and the advantages of servo drive system design within the aluminium extrusion press feeding.

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



4

2.- WORKING PRINCIPLES OF SERVO DRIVE SYSTEMS In a Tecalex servo type press feeding system every servo drive is controlled by its own control unit. The PLC system communicates with the servo drive controls via field bus. The desired speed, acceleration and torque profile of the servo drive system is sent by the PLC into the servo drive control. When a process cycle is started, manually or by automation, the PLC commands the servo drive control to start its movement cycle profile. The servo drive control then independently controls the closed loop motion of the servo motor, which provides the tightest loop with the best velocity control and the finest position resolution. Position, torque and velocity feedback from the servo motor are monitored by the PLC over the field bus. Main process parameters are displayed on the human-machine interface (HMI). When the movement cycle profile is completed, the servo drive control signals the PLC, and passes this indication to the customer’s automation. The PLC then commands the servo drive control to start its movement cycle complete profile to prepare for the next movement cycle. The PLC coordinates the speed, acceleration and torque of all servo drives within the press feeding system, monitors all system sensors and delivers any necessary data and a movement ready signal for the next process step.

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



5

3.- HOT BILLET SAW OPERATION The saw operation works based on 2 main steps. First the server pusher of the log loader will push the log out of the gas billet furnace and the saw gauge will receive the log end in order to guide it until final cutting position. During this movement the log pusher and saw gauge will work in perfect synchronization.

Fig. 2: Saw gauge leading log to final position for cutting

After reaching the final position the pneumatic driven saw clamps will close and fix the billet for cutting. The saw disc servo drive will run at full speed and the log will be cut leaving a geometrically perfect cutting surface.

Fig. 3: Clamps closed and cutting operation running

The hot saw is able to manage billet rest using an up- and down moveable billet rest shelf placed between log furnace exit and hot saw. If the profile type requires use of full billet (no divided billet

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



6

in the extrusion press allowed) the hot saw must be able to evacuate the billet rest (rest piece of the log that is too short for extrusion) out of the process. Use of full billet is common in structural profiles for automotive & aeronautical applications where no type of welding mark within the profile is accepted for safety reasons.

4.- PRESS FEEDER OPERATION The press feeding operation is based on 3 main movements. For each movement a different servo drive system will be used. First the press feeder will evacuate the billet out of the saw area and place it onto the billet shelf ready for loading to the press as shown in figure 4.

Fig. 4: Press feeder positioning billet for extrusion process

A second servo drive will now create a linear movement and feed the billet into the press as shown in figure 5.

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



7

Fig. 5: Linear movement of press feeder

After placing the billet exactly onto the extrusion axis the billet will be clamped by the front loader press stem and the press feeder shelf will tilt down, controlled by a third servo system, allowing for evacuation of the press feeder out of the extrusion press area, as shown in figure 6.

Fig. 6: Tilting movement of billet shelf and evacuation of press feeder

During front loading of the press the saw gauge of the hot billet saw will push the log back into the gas billet furnace.

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



8

5.- SERVO DRIVE ADVANTAGES There are three main advantages to servo drive technology in aluminium profile extrusion. Servo drive systems allow for precise movement cycles with each cycle having its own speed and acceleration parameters. The movement cycles of different servo drives within the press feeding can be perfectly monitored and then be synchronized which leads to low dead cycle times at very high precision. A key advantage of servo drives used in Tecalex machine manufacturing is the advanced suite of drive-integrated safety functions. These have been certified in compliance with the following latest EN ISO and IEC industry standards: EN ISO 13849-1:2008, EN 62061:2005, EN 61800-5-2:2007 and IEC 61508:1998-2000. The drives are also certified comply with the requirements for machines defined in the EC machine directive 98/37/EC (valid until 2009-12-28) and 2006/42/EC (valid from 2009-12-29). Another main advantage of servo drive systems over commonly used hydraulic systems is the low maintenance requirement of servo vs. hydraulic beside of the fact, that the use of hydraulic oil always represents a certain concern for fire prevention especially in the case of aluminium extrusion equipment were the risk of fire, due to the high process temperatures has to be taken into account. Servo motor press feeding equipment usually has a better return on investment (ROI) than other lower cost drive devices including standard AC motors or hydraulic drives. This can be explained by the fact that ROI is considering the full life cycle of the production equipment including the initial capital cost, increase of the production rate & quality, reduction of material waste, product repair, scrap & production returns, downtime, spare parts and lower maintenance cost.

SERVO DRIVE SYSTEMS IN EXTRUSION PRESS FEEDING



9