DEVICE RELATED TO ROTARY SAW BLADES

Abstract: Device for a rotary saw blade (1) for reducing the sound level during sawing and for reducing the risk of accidents due to an improved quick stop function. On both sides of a non-sawing portion of the saw blade (1) are arranged at least one against the side place of the saw blade (1) contactable member (4, 4'), arranged to facilitate a movement in direction from/towards the saw blade (1). Said members (4, 4') are arranged with channels which are open towards the side plane of the saw blade (1), and are pressed by a pressure acting means (6, 6') in direction towards the saw blade (1). Prior to start of the rotary movement for the saw blade (1), a pneumatic and/or hydraulic medium under pressure is supplied to said channels to form a pneumatic and/or hydraulic cushion between the saw blade (1) and thereagainst contactable members (4, 4'), thereby moving same from their contact position to a separated but adjacent position to the saw blade (1) with a sound and oscillating damping pneumatic and/or hydraulic pressure influence exerted on the saw blade (1).

Description: DEVICE RELATED TO ROTARY SAV7 B T ,ADES Technical Field The present invention relates to a device for rotating saw blades, intended to reduce the sound level when sawing and also to reduce the risk of injuries. Prior Art A loud sound level is a well-known problem when sawing, which initially is caused when the saw teeth of a saw blade take up contact with a workpiece, and which is amplified since a substantial part of the saw blade will act as a freely oscillating resonating member, which often amplifies the sound to an almost unacceptable sound level. Sound damping housings are prevented due to the requirement of free ejection of the saw dust formed during the sawing operation, and by the requirements relating to access and cooling of the saw blade. A further well-known problem are injuries caused due to the fact that the rotation of a saw blade can not be stopped immediately, since same is rotating with high speed and during a relatively long period of time even when the feed supply to the drive motor has been switched off. As a result thereof, many accidents or accident attempts occur, even if existing protective devices disconnect the feed supply to the drive motor. The object of the present invention is to disclose a device which substantially removes the above discussed problems, i.e. which considerably reduces the sound level during a sawing operation and also facilitates that the rotation of the saw blade can be stopped within an extremely short period of time. Summary of the Invention The device for a rotary saw blade according to the present invention is mainly characterized in that on each side of the saw blade at a non-sawing portion of the saw blade is arranged at least one member contactable against the saw blade, arranged to facilitate a movement from/towards the saw blade and being arranged with channels open in direction towards the side planes of the saw blade, pressed by means of a pressure acting means in direction towards the saw blade, before start of a rotary movement of the saw blade a pneumatic and/or hydraulic medium under pressure being arranged supplied to said channels for formation of a pneumatic and/or hydraulic cushion between the saw blade and against same contactable members, which hereby are moved from their contact positions to an adjacent but separated position from the saw blade with a sound and oscillation damping pneumatic and/or hydraulic pressure influence exerted on the saw blade. Brief Description of the Drawing A non-restricting example of an embodiment of a device according to the present invention is more fully described below with reference to the accompanying drawing, in which:- Fig. 1 shows a perspective view of an example of a device according to the invention, applied by a circular saw used to cut a log; and Fig. 2 is a schematical cross-sectional view of the example of an embodiment of a device according to the invention shown in Fig. 1, intended to illustrate the operation of same. Embodiments for Utilization of the Invention With reference to Fig. 1, 1 is used to denominate a rotary saw blade while cutting a workpiece 2, shown as a log. Below a saw table 3, onto which the workpiece 2 is fed, the saw blade 1 is surrounded on both sides by a substantially C- shaped member 4, 4', which are arranged adjacent to the saw blade 1 with a substantially plane surface, preferably having a coating or a layer of a material having a high frictional coefficient. The C-shaped members 4, 4' are arranged movable in relation to two supporting members 5, 5', having channels through which compressed air is supplied, as indicated by arrows in Fig. 2. Pressure spring means 6, 6' are also arranged, which tend to pressure the C-shaped members 4, 4' towards adjacent planes of the saw blade 1. Furthermore, the C-shaped members (not shown) are arranged with channels for the compressed air supplied from the supporting members 5, 5' , which terminate into a number of holes at the surface of the C-shaped members 4, 4' which are adjacent to the two planes of the saw blade 1. In connection with a sawing operation, and at or before the start of rotation for the saw blade 1, compressed air is supplied via the supporting members 5, 5' to the C-shaped members 4, 4', whereby same, opposed to the influence from the pressure spring means 6, 6' , are moved from the saw blade 1 to a separated but adjacent position in relation to same. This is accomplished by the formation of an air cushion between the saw blade 1 and adjacent plane of the C-shaped members 4, 4', the air leaking away from the air cushion formed being shown by dots in Fig. 2. The above mentioned air cushions will thus act in an opposed relationship to each other against the side planes of the saw blade 1, and by the part of the saw blade 1 which is not in contact with the workpiece 2, i.e. the part which during sawing is given an oscillating or vibrating movement and thereby creating an amplified and considerable part of the sound level resulting from a sawing operation. The pressure exerted against the saw blade 1 by means of the air cushions is related to the pressure of supplied compressed air as well as the pressure exerted from the pressure spring means 6, 6'. In order to facilitate adjustment of the pressure applied to the saw blade 1, this can to a certain extent be carried out by adjusting the pressure of supplied compressed air, but furthermore advantageously be carried out by arranging the pressure spring means 6, 6' with an adjustment member for increasing or decreasing the pressure exerted from the pressure spring means 6, 6' against the C-shaped members 4, 4' (not shown). Such an adjustment member may in its simplest form consist of a screw device by an end portion of the pressure spring means 6, 6', arranged to facilitate an increased/decreased pre-tension. Such an adjustment member can be influenced manually, but also be operated mechani- cally, electrically, hydraulically, pneumatically or any other suitable fashion, and influence can be arranged to be performed simultaneously at both sides of the saw blade 1. The pressure spring means (6, 6') can obviously also comprise of piston cylinders, which by means of pneumatic or hydraulic pressure press the C-shaped members 4, 4' in direction towards the side planes of the saw blade 1, the contact pressure being varied by control of the pressure for the pneumatic or hydraulic medium which is supplied to the piston cylinders. The plane of the C-shaped members 4, 4' which is directed towards the saw blade 1 is preferably arranged with a surface having a high frictional coefficient. Such a surface can, for example, be arranged as a coating of such a material or as a layer of suitable material attached to the C-shaped members 4, 4 ' , arranged with through perforations at the holes wherethrough air is supplied to form previously discussed air cushions on both sides of the saw blade 1. Should a situation occur when the rotation of the saw blade must be stopped with immediate effect, e.g. when a manually or automatically initiated emergency stop situation occurs, the supply to the drive motor is obviously disconnected, but furthermore, the air supply is also interrupted to the channels forming the air cushions between the C-shaped members 4, 4' and the saw blade 1. As a result, the C-shaped members 4, 4' are pressed against the side planes of the saw blade 1 by the pressure spring means 6, 6', and thus act in a fashion similar to the brake pads in a disk brake. Provided that the contacting surfaces as previously described have a coating or a layer of a material with high frictional coefficient, the rotation of the saw blade 1 is interrupted with almost immediate action. For those applications when piston cylinders are used a pressure spring means 6, 6 ' , the braking function can obviously be increased by increasing the pressure of supplied hydraulic or pneumatic medium when the air supply forming the air cushions is interrupted. Interruption of said air supply, as well as a simultaneous increase of the pressure for medium supplied to possibly existing piston cylinders, can easily be implemented by a person skilled in the art by use of known control techniques for pneumatic and/or hydraulic valve means. With regard to shown and described example of an embodiment, same can obviously be modified in a number of ways within the scope of the invention. The C-shaped members 4, 4' can thus obviously be given a different shape, e.g. with an increased area covering extension adapted to cover a larger or smaller part of the non-active part of the saw blade 1. With the shown C-shape, an outer peripheral portion of the saw blade 1 will be influenced by the air cushions, i.e. the part which strongly amplifies the sound created during a sawing opera¬ tion. By changing the shape of the C-shaped members 4, 4' to influence a larger area from the action of the air cushions, the sound level can be further decreased, and the braking power during an emergency stop situation will also obviously be increased. It should also be noted, that described air cushions at each side of the saw blade 1 obviously can be replaced by a liquid medium, which under pressure is supplied to the channels and the openings at the C-shaped members 4, 4*. In this case, instead of an "air cushion", a liquid cushion is formed, which dampens saw blade 1 oscillation and thus sound level during sawing operations. Previously described braking action is obtained by interrupting the supply of liquid, and furthermore, use of a liquid medium facilitates an improved cooling action for the saw blade 1. By a suitable choice of liquid medium, a greasing action can also be accomplished for such sawing operations when this is desired, e.g. when cutting metallic workpieces 2. Furthermore, the C-shaped members 4, 4' have been described as a single member on each side of the saw blade 1. For certain applications, it may be desirable to design each C- shaped member 4, 4' as two or more separated members, e.g. in order to improve ejection of saw dust, cooling liquid or similar. For the same reason, a single C-shaped member 4, 4' can be arranged with grooves or similar by the surface adjacent to the saw blade l, which divide the adjacent surface into two or more segments. The present invention is thus in no way restricted to the example of an embodiment described with reference to the accompanying drawing, since it can be further modified with regard to design and utilized pressure medium, and it is also within the scope of the invention to utilize a combination of a pneumatic and hydraulic medium, preferably supplied from with regard to each other individual channels, which results in the formation of a combined liquid and air cushion. Industrial Applicability As disclosed in the above description, the device according to the present invention comprises a combined guiding, damping and braking device, which to a substantial extent reduces previously known problems relating to an unacceptably load sound level during sawing with rotary saw blades, and which also acts as a safety device, which by means of an extremely rapid braking action considerably reduces the risk for injuries to persons during a sawing operation.

Claims: C L A T M S 1. Device for a rotary saw blade (1), c h a r a c t e ¬ r i z e d i n, that on each side of the saw blade (1) at a non-sawing portion of the saw blade (1) is arranged at least one member (4, 4') contactable against the saw blade (1), arranged to facilitate a movement from/towards the saw blade (1) and being arranged with channels open in direction towards the side planes of the saw blade (1) , pressed by means of a pressure acting (6, 6') means in direction towards the saw blade (1) , before start of a rotary movement of the saw blade (1) a pneumatic and/or hydraulic medium under pressure being arranged supplied to said channels for formation of a pneumatic and/or hydraulic cushion between the saw blade (1) and against same contactable members (4, 4 1 ), which hereby are moved from their contact positions to an adjacent but separated position from the saw blade (1) with a sound and oscillation damping pneumatic and/or hydraulic pressure influence exerted on the saw blade (1) . 2. Device according to claim 1, c h a r a c t e r i ¬ z e d i n, that the pressure acting means (6, 6*) comprises of a pressure spring, preferably having adjustable spring pressure. 3. Device according to claim 1, c h a r a c t e r i ¬ z e d i n, that the pressure acting means (6, 6') comprises of a pneumatically or hydraulically operable piston cylinder, preferably having a valve means, e.g. a by-pass flow valve, which facilitates a resilient return movement away from the saw blade (1) at a predetermined pressure. 4. Device according to any one of claims 1 - 3, c h a ¬ r a c t e r i z e d i n, that a valve means is arranged to interrupt the supply of pneumatic and/or hydraulic medium to the channels in the contactable members (4, 4') in connection with disconnection of the power supply to the drive motor for the saw blade (1) , preferably in an emergency stop situation. 5. Device according to any one of claims 1 - 4, c h a ¬ r a c t e r i z e d i n, that at least part of the surface whereby the contactable members (4, 4*) take up contact with the side planes of the saw blade (1) are arranged with a surface, a coating or a layer having a high frictional coefficient. 6. Device according to any one of claims 1 - 5, c h a ¬ r a c t e r i z e d i n, that the pressure acting means is arranged to exert an increased pressure in connection with disconnection of the power supply to the drive motor for the saw blade (1) , preferably in an emergency stop situation. 7. Device according to any one of claims 1 - 6, c h a - r a c t e r i z e d i n, that the contactable members (4, 4') are shaped to facilitate formation of a pneumatic and/or hydraulic sound and oscillation damping cushion having an extension pressing against the side plane of the saw blade (1) at least by the outer portion of same. 8. Device according to any one of claims 1 - 7, c h a ¬ r a c t e r i z e d i n, that the contactable members (4, 4 ' ) are arranged with at least two separated contact planes at each side of the saw blade (1) . 9. Device according to any one of claims 1 - 8, c h a ¬ r a c t e r i z e d i n, that the contactable members (4, 4') are substantially C-shaped. 10. Device according to any one of claims 1 - 9, c h a ¬ r a c t e r i z e d i n, that the contactable members (4, 4 ' ) are arranged with a number of from each other separated holes through which supplied pneumatical and/or hydraulical medium under pressure can flow in direction towards the saw blade (1).

Inventors: GEBELIUS SVEN RUNO VILHELM, GEBELIUS, SVEN, RUNO, VILHELM
Applicants: GEBELIUS SVEN RUNO VILHELM, GEBELIUS, SVEN, RUNO, VILHELM
Application year: 1996
Main classification: B27G19
IPC codes: B23D47, B23Q11, B27B5, B27G19, F16D55, F16D59, F16D65