COMPONENT SAW WITH TWO BLADES

The present invention relates to the saw apparatus specified in the preamble of claim 1 , which apparatus makes mitre cuts in wood blanks according to settings specified by a user.

In prior art, it is known that wood blanks are cut at specific angles in such a manner that the resulting finished components can be used to construct wood structures of specific dimensions.

These saw apparatuses known in prior art are single- or multiple-bladed. A component cut from a blank can be square, pentagonal or hexagonal in form. In a square component there is one cut made at each end. The cut is made in a straight line for its entire length. In a pentagonal component a straight lined cut is made at one end and two cuts being in an angle between each other are made at the other end. In a hexagonal component two cuts being in an angle between each other are made at both ends. In that case the wood blank has to be cut four times when using a single-bladed saw. The blank must be moved between the cuts, thus it takes time to reposition the blank. A single-bladed saw apparatus requires control automation for positioning the blank and measuring the blade angle position. A four- bladed saw apparatus has one blade for each cut, set at a desired angle, with the wood blank passing through the saw apparatus. The production costs for a four-bladed saw apparatus are high because each cut is made by a separate saw unit and the automation that individually controls it. Energy consumption is also considerably high compared to a single- bladed saw apparatus.

The double-bladed component saw according to the invention is characterized by what is disclosed in the characterization part of claim 1. Correspondingly, other embodiments of the invention are characterized by what is disclosed in the other claims.

There are several significant advantages in the use of the double-bladed component saw according to the invention. Production costs are low, because the double-bladed component saw does not need control automation. The double-bladed component saw can be manufactured to be a manually operated apparatus, thanks to its sawing jig's measuring system. Another benefit is that its energy consumption is nearly on a par with that of a sin-

gle-bladed saw, because the motors run less than a half of the time that a single-bladed saw's motor runs.

In the following, the invention will be described in more detail by the aid of an embodi- ment example with reference to the attached drawings, wherein

Figure 1 presents the double-bladed component saw according to the invention as seen from the front,

Figure 2 presents the saw blade unit, which moves longitudinal along the blank to be cut, i.e. along the X-axis, as seen from the right side,

Figure 3 presents the sawing jig's measuring system in schematic form as seen from above, with the blades positioned at the angles matching with the angle stops Kl and K4;

Figure 4 presents the sawing jig's measuring system in schematic form as seen from above, with the blades positioned at the angles matching with the angle stops K2 and K3; and Figure 5 presents one blade angular rotation mechanism according to the invention as seen from above.

Figures 1 and 2 present one double-bladed component saw 1 according to the invention. The blade unit on the left-hand side of the component saw 1 , which unit is used in component production, is attached to the frame and remains fixed in place. The blade unit 5 on the right-hand side moves essentially along its horizontal guide rails 5a in a back-and-forth motion, along the longitudinal axis X of the work piece to be cut, i.e. the blank 11 to be sawn. Furthermore, both blade units are arranged to move essentially along horizontal guide rails 5b, thus enabling an independent back-and-forth movement across the longitudinal axis of the blank 1 1 being sawn. On the saw apparatus according to the example, the moving of the blade units on the guide rails 5a and 5b is arranged to operate manually, but, if necessary, it can also be arranged to operate electrically, hydraulically or pneumatically.

The blade units and their blades 13, 14 are situated above the blank 11 being cut and the blank being cut is held in place with a locking mechanism 7. The vertical cutting movement of the blades 13 and 14 is generated by a pneumatic or hydraulic cylinder 21. The

desired length Xk of the component being cut 11 is achieved when the moving blade unit 5 is moved on the guiderails 5a horizontally to the desired measurement point. Sawing waste falls down and is collected from underneath the sawing point. The locking mechanism 7 for blanks 11 is pneumatically or hydraulically-operated and contains at least a locking claw 10, which moves along its machined groove in a steel plate pair. The locking claw 10 is concealed when the piston rod of the pneumatic or hydraulic cylinder 20 is outside. Correspondingly, the locking claw 10 pulls the blanks 11 towards the stop 15, when the piston rod of the pneumatic or hydraulic cylinder 20 is retracting into the cylinder 20.

The sawing jig forming measuring system 8 according to the invention is presented in a schematic form in Figures.3 and 4. The Figures present all seven measurement parameters for the sawing jig. The longitudinal measurement parameters are X, Yl and Y2 and the angle measurement parameters are Kl, K2, K3 and K4. The longitudinal measurement parameter X is used to set the length X _k of the component being cut 11. The desired length X _k of the component 11 is achieved when the moving blade unit 5 is moved horizontally along its guide rails 5a to the measurement point X ₂ set according to longitudinal measurement parameter X. The length X _k of the component 11 will then be X ₁ - X ₂ , where X ₁ is the position of the fixed blade unit rotation axis 2 in relation to the longitudinal axis of the piece 11 being cut and X ₂ is the position of the moving blade unit 5 rotation axis 2 in rela- tion to the longitudinal axis of the piece 11 being cut.

Longitudinal parameter Yl is used to set the position of the fixed blade unit blade 13 rotation axis 2 perpendicularly in relation to the longitudinal measurement parameter X, i.e. perpendicularly in relation to the longitudinal axis of the piece 11 being cut. Similarly, longitudinal parameter Y2 is used to set the position of the fixed blade unit 5 blade 14 rotation axis 2 perpendicularly in relation to the longitudinal measurement parameter X, i.e. perpendicularly in relation to the longitudinal axis of the piece 11 being cut.

Angle measurement parameters are set by moving the angle stops Kl, K2, K3 and K4 with threaded bars 12. In the situation illustrated in Figure 3 the blades 13 and 14 are positioned at the angle stops Kl and K4. Both of the blades 13 and 14 can be rotated and positioned to the desired one or two angle positions in line with the plane 4 formed by the cutting edge of the blade and around the essentially vertical rotation axis 2 in line with the said plane.

The rotation axis 2 of the blades 13 and 14 can intersect and be perpendicular to the axes of rotation 3 of the blades 13 and 14, or the rotation axis 2 can be in an essentially vertical position at any point on the plane 4 formed by the cutting edge of the blade. This feature is exemplified in Figures 3 and 4 by presenting the position of the rotation axis 2 for both blades, where the rotation axis 2 intersects the blades' axis of rotation 3, and one alternative position, where the rotation axis 2 does not intersect the blades' axis of rotation 3.

In practice, the plane 4 formed by the cutting edge of the said blade is the essentially vertical plane formed by the blade bits' cutting edge facing the blank 11 being cut, which bits are made of hard metal or similar and are wider than the body of the blade 13, 14.. Thus, when the blades 13 and 14 are rotated into such a position that they are essentially parallel, the said planes 4 are on the blade 13, 14 sides that are facing one another.

Due to the measuring system 8 forming the sawing jig, it is possible to realise a simple me- chanical angle rotation mechanism 6 to rotate the blades 13 and 14 around an essentially vertical angle rotation axis 2. If the angle rotation axis 2 were, for example, on the middle plain of the rotation direction of the blade, and on the vertical axis in line with the said middle plain, the longitudinal measurement parameters X, Yl and Y2 should be adjusted as a function of the angle measurement parameters Kl, K2, K3 and K4. This would require a trigonometric calculation and, as a result, it would not be possible to implement the component manufacturing saw apparatus 1 according to the invention as economically.

In Figure 4 the blades 13 and 14 are positioned at the angle stops K2 and K3. The blades 13 and 14 have been rotated counter clockwise with the angle rotation mechanism 6 com- pared to the situation illustrated in Figure 3, where the blades 13 and 14 are positioned at the angle stops Kl and K4.

Figure 5 presents the angle rotation mechanism 6 of the blades 13 and 14 according to the invention in greater detail. The angle rotation mechanism 6 consists at least of a frame and a bidirectional torsional device 9 attached to it to rotate the rotation axis 2 around its central axis. The angle rotation mechanism 6 also consists of at least a belt or chain pulley 18, whose central axis joins the rotation axis 2; a toothed belt or chain 19, which is arranged to go around the belt or chain pulley 18 and to which is also attached a carriage 22, which is

carried along by the said belt or chain 19 along essentially horizontal guide rails; and angle stops Kl, K2, K3 and K4, against which the carriage 22 can be positioned when setting the sawing angles. When setting the sawing angles, the position of the angle stops Kl, K2, K3 and K4 is changed essentially horizontally using the threaded bars 12. The toothed belt 19 5 also functions as a shock absorber, when the carriage 22, which moves along the guide rails, is being positioned against the angle stops Kl, K2, K3 and K4.

The blade angle rotation mechanism 6 is pneumatically or hydraulically operated and executed in such a manner that the pressure remains on when the rotation movement stops at 10 the angle stop Kl, K2, K3 or K4 with the carriage 22. Power of the pneumatically or hydraulically operated torsional device 9 of the angle rotation mechanism 6 keeps the blade 13, 14 at the set angle during the sawing. Another set angle position is achieved when the rotation direction of the torsional device 9 is reversed.

15 The sawing angle, i.e. the cutting angle values are read from the linear measuring scale 23 scaled by the belt or chain pulley 18 shown in Figure 2. The angle rotation mechanism 6 changes the circular angle scale into a linear scale, thus providing sufficient accuracy in cutting angles. The measuring scale 23 is permanently affixed to the device frame, immediately above or below the carriage 22, which moves along the guide rails, and the carriage

20 22 is fitted with a thin indicator needle, which is arranged to move on top of the measuring scale 23.

The above description represents the most advantageous embodiments of the invention. However, the invention is not limited to these embodiments, but it may be varied within

25 the scope of the patent claims presented hereinafter. A double-bladed component saw can be, among others, supplied with a complete control automation, which would comprise, for example, automatic blade positioning electrically to the angle positions defined by the the angle stops Kl, K2, K3 and K4. The sawing jig's longitudinal measurement parameters X, Yl and Y2 can also be automatically positioned electrically, hydraulically or pneumati-

30 cally. This primarily means that the moving of the blade units along the longitudinal and lateral axes of the blank being cut as well as the locking of the units in the correct position is carried out with electrical, hydraulic or pneumatic operational elements instead of manual moving and locking. Furthermore, the positioning can be done either partly or com-

pletely automatically or completely manually. The double-bladed component saw can also be made fully automatic, with all functions controlled completely automatically.