Development of the model of input control of timber for the enhancement of operational performance of sawn stream

. In this article, a task of enhancement of the operational performance of modern sawing equipment, is set and solved. One of the necessary element thereof is to install scanners of presence of metal inclusions (metal detectors) on the feed line of bolt timber. In this article the control object under observation is the small sawing line based on two round-sawing machines KARA MASTER. It is proposed for the line that a classic technological scheme should be modified in a way the bolt timber, moving through a conveyor, to be passing an aperture of metal detector. In this article, the approach for algorithmization and programming of the control system is proposed to be SWITCH-technology and the corresponding area of programming, an automata-based programming. This technology, made a perfect showing for controlling of various objects, is proposed to be introduced for developing of models of typified technological process of small timber sawing. The first section in your paper.


Introduction
In using the usage of the modern sawing equipment, an important task is to enhance its operational performance. One of the necessary element thereof is to install scanners of presence of metal inclusions (metal detectors) on the feed line of bolt timber. They help to avoid standstill of production lines and eliminate repair costs of the expensive equipment and other losses caused by metal objects falling into producing equipment (the cost of a professional saw may be as high as 500 Euros), as well as to provide for a metal-free output of the finished commodity. This is especially important for the European part of Russia, where aged woods often consist of many metal inclusions, resulting from the World War II.
Presently, one of the biggest companies engaged in production of the equipment for small and medium sawing is Kallion Konepaja Oy [1]. Round-sawing KARA MASTER machines for sawing of logs meet high standards, as far as safety, dynamic and effectiveness criteria are concerned. In this article, the control object under observation is the small sawing line based on two round-sawing machines KARA MASTER ( fig. 1). According to the technological diagram, after the log has passed the chain conveyor installed outside the workshop, it is being passed onto the chain conveyor installed before KARA MASTER machines; then, with the assistance of single-piece feed unit, the log goes to the vacant machine. The operator of the machine monitors the log visually, identifiesby the diameter of the thin end -the method of the cutting of the log in accordance with the functional specification. Thereafter, in accordance with process chart, a program is to be chosen, and the log goes sawed into slabs, cut and uncut boards. The operator of the second machines follows exactly the same procedures. Then, the cut boards are moved through a roll-table to the gravitational log kicker, where they, subject to gravitational forces. fall through slanted guide to the sorting place and are packed into parcels. The slabs not suitable for further processing go to the line transporter for removal of the waste, whereas uncut boards are being sawed into boards of the required width, coming to the crosscut saw.
We propose modifying the classical design in a way that the bolt timber being transported though the conveyor to pass the aperture of a metal detector. Once unauthorized metal inclusions have been detected, the electronic system will alarm accordingly, stopping the feeding conveyor. The removal of logs containing metal is to be made to a special pocket located behind metal detector.

Development of model
In order to develop a model of logical control of metal detector and a log conveyor transporting logs from metal detector zone to barking/waste zone, it is proposed to use so called SWITCH-technology [2,3], being the development of a functional software for systems of logical control, on the ground of finite determined automates theory. Such a technology made a good showing for controlling of various objects [4][5][6][7][8][9], is supposed to be implemented for development of models of typified technological process of small sawing.
The transition graph of the system of logical control of a metal detector ( fig. 2) is based on 5 fundamental states: 0.
"WAITING FOR THE LOG". The initial state of metal detector. In this state, the drive of the inner conveyor is locked, and the sensor of metal detector is switched off. 1.
"HANDLING OF THE LOG". The state is to be occupied by metal detector, once a log is detected in the feeding zone.

2.
"ME INCLUSIONS PRESENT". This state is to be occupied by metal detector, once metallic inclusions are registered in the log being handled. 3.
"ME INCLUSIONS ABSENT". This state is to be occupied by metal detector, once absence of metallic inclusions is registered in the log being handled. 4.
"TRANSIENT LOCK". This state may be occupied by the system, once a signal is received from log conveyor, blocking the conveyor itself and all system feeding logs into the workshop as well. Arcs of the graph show which conditions cause change of state and which do not (so called loops). It is customary to show input actions of the present transition, and output signals being generated. In the initial time, the controlling automat is in "WAITING FOR THE LOG" state; in this state the drive of inner conveyer of metal detector is locked (z42), the sensor of presence/absence of metal inclusions is switched off (z44).
Once a signal confirming presence of the log in the feeding zone is received (x11), the controlling automate switches to a state "HANDLING OF THE LOG". The input signals change: the drive of the inner transporter of metal detector is activated (z41), a signal for switching the sensor of presence/absence of metallic inclusions is sent (z43).
The processed log travels through internal conveyer to the log conveyer (x21), whilst the automate controlling metal detector, switches either to "ME INCLUSIONS PRESENT" of "ME INCLUSIONS ABSENT" state, depending on the presence of inclusions, accordingly. Either state is occupied by automate until it is registered that the log is delivered to the barking zone.
The above modus operandi can be applied if log conveyor is not locked, i.e. there is no log in the end of log conveyer (!х31). Otherwise (х31), the system switches to "TRANSIENT LOCK" state, giving out signals to lock all moving and driving parts of the controlled object. Once the locking signal of the log conveyer is cleared on !х31 input, the system reverts to the state preceding the moment of lock.
The models developed on the basis of the suggested approach, allow to automate receiving control programmes for programmed logical controllers which operate the line of small sawing, on the base of those the essence of control systems is built, thus in the end favour the increase of the productivity and the quality of the sawing process.