DE3009663A1 - Tree trunk cutting process - using second computer to control conveyor speed for faster cutting - Google Patents

Abstract

The tree trunk to be cut is measured, the results are fed into a computer, and the tree is axially moved by a conveyor into a cutting appliance, when it is retained for the period of time necessary for cutting. A second computer is programmed on the base of the data coming from the first computer, to select an acceleration/deceleration suitable for the drive unit (11) of the conveyor (5-7). The conveyor speed is accelerated during a first period of time (to-tl) and deceerated during a second period (t3-t6) until the conveyor is stopped. The cutting process is initiated before the conveyor is stopped and the acceleration phase of the conveyor is begun before the cutter (2) returns to the at-rest position.

Description

Method of dividing an elongated object,

especially of a tree trunk, in the desired lengths These The invention relates to a method for dividing an elongated object, in particular a tree trunk, in desired lengths, where - the one to be divided Counteratand in a manner known per se with regard to its length, its cross-section, its curvature, etc. is measured, - the measurement results for the purpose of determining the Cut-off points are fed into a first computer, and - the cut-off Object is conveyed axially with a conveyor into a cutting device, at which it is paused for the period of time necessary for cutting.

When dividing a tree trunk into suitable ones for industrial use Lengths, the intended use must be taken into account, which is different from the parts Properties in terms of length, cross-section and quality are required. Factors that have an effect on the quality are, among other things, the abundance of branches, the curvature, the rottenness, the columns etc. The length is often a multiplied number of a module and can also a certain excess for the compensation of the ends that takes place in the process contain. The length module varies in different market areas and is e.g. for saw logs 25 or 30 cm. From time to time there are also between the module masses Lengths needed.

There are two main processes in the timber industry depending on how the tribe is divided. In the Nordic countries mainly the so-called wood product method is used, according to which the tree is felled, pruned and is cut into desired types of wood in the forest.

In the past, this work was done manually with a hand or chainsaw, Nowadays, however, machines suitable for work (forest tractors, processors, Harvesters etc.) available.

In Eastern Europe, Central Europe and North America, the whole trunk method is often used used, according to which the tree in the forest is felled manually or by machine, if necessary trimmed and de-limbed, after which the trunk is transported to a factory, where the division takes place.

With the whole tree and whole trunk methods, an automatic Measurement can be applied, and by means of modern measuring equipment, besides the diameter and the length also the variation of the diameter over the whole Length of the trunk as well as the elliptical shape, the curvature, the number of branches and others Quality factors are taken into account. A computer can use the measurement results Calculate the economically and technically optimal cutting program.

Disadvantages with the wood goods process are the inaccuracy as well the fact that the cutoff is too long because of the time and geography Distance between the determination of the cutting requirement and the cutting process cannot be executed in accordance with the market situation. As the wood raw material has become more expensive, attention is lost to that caused by incorrect allocation Waste has been directed to find means to improve this situation.

In the whole-tree or whole-stem methods, the stems are generally machine cut. The trunk can be in either transverse or longitudinal direction the cutter can be fed.

In the transverse process (Fig. 1), the trunk 1 is transported by means of a transverse conveyor promoted to the cutting area, where several circular saws 2 are available, of which desired saws can be moved vertically into the cut-off position and which can then cut the trunk into pieces of the desired length. advantages of this process include: - the high cutting speed, because several simultaneously cutting blades are present, and - the good accuracy because of the firm Assembling the leaves.

Disadvantages of the process include: - the high costs of the system, - the fixed cut-off lengths determined by fixed modules, - the requirement, to leave a balance reserve, which is the choice of an optimal length combination limited, and - the fact that the tree can rotate when cut, with the saw blades can be damaged.

In the case of axial cutting, the trunk is transported by means of a longitudinal conveyor fed into the cutting device, the conveyor for the cutting process is stopped (Fig. 2).

In order to achieve an exact determination of the cut-off length, you can adjustable stops 3 are used, of which a desired stop in the functional position is shifted so that the trunk bumps against it and stops and the sawing process can take place. This process includes, among other things. the following Advantages achieved: - a favorable price, - an exact cutting length, - a failure blade damage and - any combination of module lengths.

Disadvantages of the method are: - the fact that only module lengths can be chosen - the slowness of the process because stopping against the attack takes a long time, and - the fact that the attacks mechanically very hard.

The axial feeding of a trunk can also be done without become (Fig. 3) that the distance covered by the tree trunk e.g. with one at the turning point of the conveyor arranged pulse generator 4 is measured and the conveyor at the correct Position is stopped.

Advantages of this process include: - low costs, - the possibility of cut any length, i.e.

also lengths between modules by the desired length combinations, and - the absence of broken leaves.

The disadvantage of the process is that it is slow because of the strain due to the measuring accuracy must not move in relation to the conveyor and therefore a low conveying speed must be used.

According to this invention, the tree trunk becomes in its longitudinal direction fed into the cutting device and the conveyor is used for the cutting process stopped as in the aforementioned procedure, but the new procedure is different differs from the earlier ones in the following respects: - It becomes a driving system of the conveyor used, by means of which the speed of the conveyor both during acceleration and deceleration as known and controllable at a constant conveying speed is.

- A cutting saw arrangement is used in which the stroke of the saw in relation to the infeed movement of the log is so controllable and can be timed so that unnecessary waiting times can be avoided. Of the Trunk can if necessary by means of a together with the cutting device or be held separately adjustable holder.

- A computer is used to control the Sponsor and the stroke of the cutter so that an unnecessary waiting time can be avoided.

- The computer-controlled acceleration and deceleration of the conveyor can be designed so that the sliding limit determined by the coefficient of friction is not boom-stepped. The trunk can also be moved by means of a transverse stop or a mechanical pressure element.

The method according to the invention is mainly characterized in that that - a second computer based on the data received from the first computer is programmed, a suitable acceleration for the driving device of the conveyor or delay to be selected so that - the conveyor speed vT of the conveyor in a first phase of the promotion at least for a certain first period of time is accelerated, - the conveying speed vT of the conveyor at least over a certain subsequent second period of time is delayed until the conveyor to the Has been brought to a standstill, - the cutting movement of the cutting device is started even before the conveyor stops moving, and - the following Acceleration phase of the conveyor even before the cutting device withdraws retirement is started.

Controlled operation of the conveyor is ensured by a servo motor, Stepping motor or the like brought about, which is regulated by means of a computer. Because the movement of the conveyor is controlled, the computer has at the same time Information about the distance covered by the tree trunk.

The stroke of the saw is also controlled by the computer.

The advantage of the procedure compared to the normal, through axial Infeed truncation is the much higher speed, being - the transport speed of the tree trunk with the help of the acceleration and deceleration phases can be increased significantly and - the waiting time of the trunk when cutting is significant is shortened because the stroke of the saw can be significantly accelerated.

Another advantage is that all possible lengths and whose combinations can be cut off with balancing reserves, whereby the Optimal cutting operation made possible by the computer was exploited to the full can be.

The invention is described below with reference to the accompanying figures 4 to 6 considered in more detail.

FIG. 4 shows a device partly schematically and as a side view for performing the method according to the invention.

FIG. 5 shows a cutting device known per se in the cutting plan.

Figure 6 graphically shows the speeds of the conveyor and the Cutting device as a function of time when using the inventive Procedure.

In Figure 4, where for the sake of clarity mainly analog designations As used in Figures 2 and 3, a feed conveyor 5-7 is shown, which comprises a chain or belt 5 that is wrapped around a belt mounted on the frame 7 of the conveyor Driving wheel 6 is running. This friction wheel 6 is of a driving device 11, e.g. Stepper motor or a servo motor. At the end of the feed conveyor on the driving wheel side 5-7 starts in the direction of transport of the tree trunk 1 in some Removal of a discharge conveyor 8-10, correspondingly a chain or a Belt 8 includes, around a mounted on the frame 10 of the discharge conveyor wheel 9 and a similarly mounted friction wheel (not shown) runs.

The cutting device 2 according to Figure 5 is a circular saw that in the area between the feed conveyor 5-7 and the discharge conveyor 8-10 transversely is arranged to the transport direction of the tree trunk 1. It includes a saw blade 15, which is rotatable at the end of one leg of an approximately L-shaped carrier 14 is stored. The carrier 14 is but its other leg on the frame 12 of the cutting device 2 pivoted. The back and forth cutting movement a - b - c becomes brought about by means of a hydraulic cylinder 13, which at one end of the Frame 12 and at its other end at the junction of the legs of the Carrier 14 is stored. The hydraulic cylinder 13 is in a known manner e.g. regulated by a linear motor.

The function of the system can be detailed with the help of the timing diagram be considered according to Figure 6, in which the movement of the conveyor 5-7 and the stroke of the cutting device 2 is shown in a common coordinate system are.

It should be noted, however, that only one option is given here is how the movements can be timed to match each other. In practice can always be related to the movement properties of the various organs as well time diagrams deviating from the mutual relations can be obtained.

In the upper coordinate system the speed ve of the infeed conveyor is represented as a function of time.

The stroke speed is again in the lower coordinate system the cutter v, shown as a function of time.

The movement of the infeed conveyor and the cutting process get lost in terms of time as follows: At the moment t0 the feed conveyor becomes 5-7 after the termination a previous cutting operation or when a log was placed on the conveyor has been approached.

The allowed acceleration is determined by the coefficient of friction between determined by the tribe and the sponsor.

At the moment t1 the conveyor 5-7 has its maximum speed reaches and continues its movement at a constant speed. If the object to be cut is very short, the conveyor will not reach its maximum Reach speed, but the speed starts at the moment t2, to delay.

At the moment t3 the movement of the conveyor begins to decelerate. The maximum deceleration is determined, for example, by the coefficient of friction between the wood and the sponsor. The controlling computer calculates from the measurement results and the cut-off program shows the time course of the blow of the cut-off device (e.g. a circular saw).

At the moment t4 the impact of the cutting device 2 begins (Curve B). The speed of the stroke increases with maximum acceleration at. In this example, the stroke does not reach its maximum speed.

At the moment t5 the blow of the cutting device begins to to delay.

At the moment t6 the trunk 1 has come to a standstill, the leaf 15 of the saw has reached the surface of the log 1 and the speed of the Blow has fallen to the value of the cut-off blow. The cutting process of the tribe begins. When the saw blade 15 penetrates the wood, it is initially delayed the blow then begins to grow again when the saw blade 15 is halfway has exceeded through the trunk, and is delayed again to zero when the saw blade has penetrated the trunk.

At the moment t7 the trunk has been cut off.

The stroke of the cutting device 2 goes backwards at maximum speed over.

At the moment t8 the saw blade 15 reaches the surface again of the sawed-through log 1. The infeed conveyor 5-7 starts up and the cycle begins from the beginning again.

At the moment tg the cut of the cutting device 2 begins, to delay.

At the moment t10 the cutter is in its retirement returned.

The trunk can be held in place with a mechanical holder, which moves together with the cutting device 2 or which is regulated in this way, that he grips the trunk before starting the cutting process, whereby the acceleration of the conveyor can be increased 5-7.

The blow of the cutter can be significant before Start moment t4 (e.g. moment t4, curve A), because there is plenty of time is available. The speed of the stroke increases so that the Speed vC a speed corresponding to the cutting process at the same time when the saw blade 15 reaches the surface of the object to be cut and this has stopped at the same time.

It should be noted in the end that the inventive idea is also expressed in this way are k ffi when the first computer in a known manner the optimal state calculated, the second computer regulates and realizes this optimum. It is to be noted that said first and second computers capture as functional definitions are and can of course be contained in a common computer apparatus in practice be.

Claims (8)

Claims: 1. Method for splitting an elongated Object, in particular a tree trunk, in the desired lengths, the one to be divided Object in a manner known per se with regard to its length, its cross-section, its curvature, etc. is measured, the measurement results for the purpose of determining the cut-off points fed into a first computer and the object to be cut off with a conveyor is conveyed axially into a cutting device, in which it is for the time required for cutting is stopped, thereby g e k e n n z e i c h n e t that a second computer based on the received from the first computer Data is programmed, one for the driving device (11) of the conveyor (5-7) select suitable acceleration or deceleration so that the conveyor speed vT of the conveyor (5-7) in a first phase of the promotion at least one certain first time period (to-t1) is accelerated, the conveying speed vv of the conveyor (5-7) at least for a certain subsequent second period of time (t3-t6) is delayed until the conveyor (5-7) has come to a standstill, the cutting movement of the cutting device (2) before the stopping of the Movement of the conveyor (5-7) is started (time t4), and the following acceleration phase of the conveyor (5-7) before the withdrawal of the cutting device (2) in the Retirement is started (time t8). 2. The method according to claim 1, thereby g e k e n n z e i c Note that a stepping motor is used as the driving device (11). 3. The method according to claim 1, thereby g e k e n n z e i c Note that a servo motor is used as the driving device (11). 4. The method according to claim 1, thereby g e k e n n z e i c That is, the second computer is arranged to track the movements of the conveyor (5-7) so that unnecessary waiting times are reduced or minimized. 5. The method according to claim 1, thereby g e k e n n z e i c That is, the second computer is arranged to control the speed of the conveyor (5-7) to regulate that by the coefficient of friction between the conveyor (5-7) and the object to be cut (1) determined maximum acceleration or delay is not exceeded. 6. The method according to claim 1, thereby g e k e n n z e i c h n e t that the object to be cut (1) by means of a mechanical holder is held, together with the regulation of the cutting movement in the holding Position is controlled. 7. The method according to claim 6, thereby g e k e n n z e i c n e t that the mechanical holder by means of the second computer in the retaining Position is controlled so that the holder is in the holding position when the cutting device (2) begins to penetrate the object to be cut (1). 8. The method according to claim 1, thereby g e k e n n z e i c Note that the first and second computers share a common computing device is used.