Safety device for circular saw machines

Abstract

The invention relates to a circular saw comprising: a machine frame; a workpiece support surface (WA) connected to the machine frame; a sawing unit having a saw blade mounting for rotatably mounting a saw blade (210) about a saw blade axis (11; 211); a safety device for rapidly moving the saw blade in a hazardous situation, having a hazard-detection device (250, 260) and a rapid-movement device (240) in order to move the saw blade from an operating position (10a') into a safety position (10b'), wherein a feed direction (Z) is defined by the workpiece support surface and the saw blade axis, which feed direction runs parallel to the workpiece support surface (WA) and perpendicular to the saw blade axis (11; 211). According to the invention, the rapid-movement device has a guiding device (220, 221) for guiding the saw blade axis from the operating position (10a') into the safety position (10b1), and the guiding device is designed to guide the saw blade axis from the operating position along a movement path (FB) which, at least at the start of the rapid movement, includes a directional component (SB"z) that runs in the feed direction (Z).

Description

[0001] Safety device for circular saw machines

[0002] The invention relates to a circular saw comprising a machine frame, a workpiece support surface connected to the machine frame, a saw unit movably guided in the machine frame, a saw blade bearing arranged on the saw unit for rotatably mounting a saw blade about a saw blade axis, a safety device for rapid movement of the saw blade in a hazardous situation, with a hazard detection device designed to detect a hazard to a part of a user's body from the saw blade and to generate a hazard signal upon detection of a hazard, and a rapid movement device that is signal-technically connected to the hazard detection device for receiving the hazard signal and is designed to move the saw blade rapidly from an operating position to a safety position upon receiving a hazard signal.in which the saw blade poses less of a risk to the user's body part than in the operating position, in particular not at all, wherein the workpiece support surface and the saw blade axis define a feed direction that runs parallel to the workpiece support surface and perpendicular to the saw blade axis. A further aspect of the invention is a method for preventing injuries on circular saws and the use of a rapid movement device for quickly moving a circular saw blade. Circular saws are among the machine tools used in many applications and industries. They are used by both well-trained users and users with little experience in operating the machine tool. It is known that user injuries frequently occur when using circular saws. In particular, the user's hands and fingers are affected, as they are injured by the rotating circular saw blade.

[0003] From DE 20 2017 106 201 U1, various variants of a safety device are known that aim to reduce the risk of injury to a user of circular saws. One of the variants disclosed in this document is to decelerate the rotation of the circular saw blade and lower the blade below the workpiece support surface when a hazardous situation is detected. Both measures can reliably prevent cuts caused by the rotation of the circular saw blade. To achieve this even during rapid or accelerated hand movements towards the circular saw blade, this document proposes hazard detection algorithms that detect the speed and acceleration of the hand's movement within a monitored area and, based on these values, predict the occurrence of a potential hazardous situation.The problem with this approach is that in the typically occurring, particularly dangerous situations, such as the hand slipping off the workpiece while pushing the workpiece forward, either a large safety area in front of the saw blade must be monitored or the saw blade must be lowered particularly quickly to prevent contact between the hand and the saw blade at such approach speeds, which can reach 2 meters per second.

[0004] A safety device is known from US patent 2002 / 0170399 A1 in which the circular saw blade is rotatably mounted about a circular saw blade axis, which in turn is pivotally mounted on a pivoting lever. A friction brake device, which can engage the saw blade abruptly, causes a strong deceleration of the circular saw blade's rotation, and the braking torque simultaneously pivots the circular saw blade about the pivoting axis of the pivoting lever, thereby lowering it below the table. For this purpose, the pivoting axis of the pivoting lever is located on the side of the ascending saw blade teeth, i.e., behind the saw blade axis in the workpiece feed direction.While this device has the advantage of utilizing the kinetic energy stored in the saw blade's rotation to lower it, resulting in greater energy utilization for larger blades than smaller ones, thus achieving efficient energy conversion for the high force required to accelerate and rapidly lower the blade when working with larger blades, this type of rapid lowering mechanism has proven to have at least two significant drawbacks. Firstly, the acceleration generated by the braking torque is insufficient to reliably prevent injury. Secondly, the braking action on the saw blade damages it, necessitating blade replacement every time the safety system is triggered, including false alarms.

[0005] From EP3403762B1, a device is known in which the saw blade can be lowered without damage. For this purpose, the saw blade is guided linearly and lowered vertically. To achieve a high lowering acceleration and speed, the saw unit is held in the raised operating position against gravity and against additional supporting spring elements by means of controllable electromagnets and can be rapidly lowered by reversing the polarity of the electromagnets, whereby a superimposed magnetic force, gravity, and spring force act on the saw unit.Although this device can generate high forces to achieve vertical acceleration of the saw unit, it requires considerable technical effort, which must include the holding magnets and their control as well as the tension springs, but also a device that moves the saw unit back from the lowered safety position to the operating position after it has been triggered, working against gravity and the spring force.

[0006] From EP 3318357B1, a further variant of a quick-lowering device is known, in which a combination of a pivot bearing of the saw blade axis on a pivot lever, the pivot axis of which lies behind the saw blade axis in the feed direction, and a linear actuator, which is coupled to the pivot lever in the area of ​​the saw blade axis, is realized for the vertical lowering of the saw blade. A special feature of this device is the frame-fixed arrangement of the linear actuator, which is made possible by the actuating rod of the linear actuator being coupled below the saw blade axis to a ring rotatable about the saw blade axis by means of a coupling joint, and extending obliquely downwards from this coupling into the area below the pivot axis.It has been shown that this device requires a high-force pneumatic actuator to achieve sufficiently rapid lowering when large saw blades, for example, those with a diameter of 500 mm or more, are used and these saw blades have a large overhang, such as when set to maximum overhang. Therefore, the necessary equipment is also complex to prevent injury in the most dangerous typical application scenario: a large saw blade operating in a position with a large overhang, especially when approaching at high speed.

[0007] From WO2022 / 157037A1, another safety device for circular saws is known. In this safety device, the saw blade is lowered linearly and vertically using a spindle drive. While this lowering device has the advantage that the spindle drive can be used for both rapid lowering and finely adjustable blade overhang, a very powerful servo motor and spindle drive are required to achieve the necessary high acceleration forces, even with large saw blades and blade overhangs.

[0008] A fundamental problem with safety devices for circular saws is that when a saw blade with a large diameter, set to a large blade overhang and thus extending, for example, 200mm or more beyond the workpiece support surface, poses a particularly high risk of injury due to the large surface area of ​​the saw blade, while at the same time a particularly long distance must be covered until the saw blade is completely lowered below the workpiece support surface, and a particularly large mass must be moved in the process.Therefore, if premature rapid-movement triggering – and thus many false triggering – is to be avoided, significant effort must currently be invested in the actuators used, specifically adapted and designed for this particular hazard situation, to reliably prevent injury even under such adverse conditions. This results in high manufacturing costs and therefore hinders the widespread use of such effective safety devices.

[0009] It is therefore an object of the invention to effectively increase occupational safety on circular saws, especially under such unfavorable conditions, while simultaneously reducing the equipment required. This object is achieved according to the invention with a circular saw of the design described above, in that the rapid movement device has a guide device for guiding the saw blade axis from the operating position to the safety position, and the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, along a path of movement which, at least at the beginning of the rapid movement, includes a directional component that runs in the feed direction, and / or that the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, along a path of movement (FB).on which the direction of the rapid movement from the starting point of the rapid movement to a point on the movement path, which lies at 50% of the length of the movement path between the operating position and the safety position, includes a directional component that runs in the feed direction..

[0010] The invention is based on the understanding that a combination of different safety measures is particularly effective in reliably preventing cuts from circular saws. Firstly, the known practice of slowing down the saw blade rotation is a suitable measure to prevent cuts, as is the known practice of quickly moving the saw blade, for example, under the workpiece support surface. These two measures eliminate the cutting effect of the saw blade by stopping its rotation, and secondly, they prevent the hand from coming into contact with the saw blade by quickly moving the blade, for example, by lowering it under the workpiece support surface.

[0011] The basic principle here is that the operating position is defined as the position of the saw blade axis in which the saw blade has its maximum projection over the workpiece support surface – meaning the saw blade axis is adjusted to achieve the minimum distance to the workpiece support surface. This ensures that the horizontal directional component, which is advantageous for injury prevention, is achieved at the beginning or in the first half of the rapid movement, precisely for the most injury-prone saw blade position.

[0012] The inventors recognized that a third measure is advantageous for preventing injuries when the saw blade is operated with only a small blade overhang or when small-diameter saw blades are used. In this case, a rapid lowering action shifts the entry point of the saw blade circumference, i.e., the cutting teeth of the saw blade, into the plane of the workpiece support surface in the feed direction during the initial stroke. This is because the tangent of the saw blade circumference at this entry point runs obliquely at an acute angle, and this angle is further reduced by the lowering movement. This results in a beneficial increase in distance between the hand, which typically approaches the saw blade in the feed direction, and can thus contribute positively to preventing contact.

[0013] However, this effect occurs only to a very small extent when a large-diameter saw blade is used and operated with a large blade overhang. In this case, the tangent to the saw blade circumference in the workpiece support surface runs almost vertically, so that during the initial stroke of the circular saw blade's downward movement, virtually no additional horizontal distance is gained between the saw blade circumference and the hand approaching in the workpiece feed direction.According to the inventors, this is particularly disadvantageous, since this initial phase, in which the initial section of the rapid movement of the circular saw blade takes place (which, according to the invention, is understood to be the first section of movement over approximately 10 to 30% of the total rapid movement of the saw blade during rapid movement), is crucial for reliably preventing injuries, because here, due to the still low lowering speed at the beginning of the acceleration of the saw blade, the hand comes closest to the saw blade and consequently there is the greatest risk of an injurious contact.

[0014] According to the invention, the rapid lowering action of the high-speed movement device is guided by a guide device for the saw blade axis. This guide device moves the saw blade axis from the operating position to the safety position. The guide device is specially designed according to the invention to guide the saw blade axis from the very beginning of the rapid movement in such a way that it moves with at least one directional component in the workpiece feed direction. A directional component is understood here to be a directional component of the saw blade axis's direction of movement, which, according to a vector decomposition, must exhibit this directional component in the workpiece feed direction. For example, a downward downward lowering movement of the circular saw blade in the workpiece feed direction results in a guide that exhibits such a movement component in the workpiece feed direction as implemented by the invention.The saw blade axis, guided by the guide device according to the invention, therefore moves, when the rapid movement is performed as rapid lowering, in a direction of movement at the start of the rapid lowering which lies in an angular range from inclusive 0° to the horizontal to exclusively 90° to the horizontal, wherein this angular range is enclosed in a side view by a beam extending from the saw blade axis in the workpiece feed direction and a beam extending vertically downwards from the saw blade axis.

[0015] This initial movement of the saw blade axis causes the saw blade to move from the outset in such a way that the distance between a hand approaching the saw blade in the workpiece feed direction and the saw blade circumference increases due to the rapid movement of the saw blade. While this increase caused by the saw blade movement often cannot prevent an absolute reduction in the distance between the hand and the saw blade circumference at high approach speeds in the initial phase, if the rapid movement process is initiated sufficiently early, it results in a further increase in the distance due to the accelerated movement of the saw blade. This means that, particularly within the first milliseconds of the lowering movement, a crucial gain in distance is achieved for reliably avoiding contact.This makes it possible to use less powerful actuators compared to previously known devices, such as the vertical linear movement known from WO 2022 / 157037 A1, in which the saw blade axis has no directional component in the workpiece feed direction at the beginning or during the rapid lowering process, or compared to the device known from EP 3318357 B1, in which the saw blade axis, due to the pivot axis located behind and below the saw blade axis in the workpiece feed direction, even has a movement component against the workpiece feed direction at the beginning of the rapid lowering process, and thus dangerously shortens the distance between the saw blade circumference and a hand approaching in the workpiece feed direction in the initial phase of the rapid lowering process, since the distance between the approaching hand and the saw blade circumference is favorably increased due to the favorable direction of movement of the saw blade axis.

[0016] In accordance with the invention, the feed direction or workpiece feed direction is understood to be the direction in which a workpiece is fed to the saw blade, i.e., the relative movement of the workpiece with respect to the saw blade axis. For example, in a circular saw designed as a panel saw, this feed direction runs along the plane in which the saw blade lies, i.e., perpendicular to the saw blade axis, and along the plane formed by the workpiece support surface, thus corresponding to the straight line along which these two planes intersect.A circular saw is typically operated so that the teeth of the saw blade, at the point where the blade enters the workpiece support surface, move towards the workpiece support surface. In the case of a panel saw, this means the teeth plunge into the slot in the workpiece support surface at the front end (relative to the feed direction) and emerge from the slot at the rear end of the saw blade (relative to the feed direction). The cut is then made at the front end by the penetrating teeth of the saw blade. This point is also the main hazard for hand injuries from the saw blade.

[0017] The basic principle is that the guide device is designed to move the saw blade from at least one operating position into the safety position such that, at the start of the rapid movement, the path of motion includes a directional component that runs in the feed direction. Preferably, this operating position is the position in which the circular saw blade has a maximum adjustable blade projection, i.e., the saw blade is set for cutting workpieces of particularly large thicknesses, and consequently, the portion of the circular saw blade protruding from the workpiece support surface is at its maximum. Typically, this maximum blade projection is limited by the position of the saw blade axis and its corresponding bearing arrangement, which prevents the axis from passing through a saw blade slot in the workpiece support surface.It is further preferred that the rapid movement from any operating position is guided along a path of motion which, at least at the beginning of the rapid movement, includes a directional component that runs in the feed direction. In this preferred embodiment, the feed direction component is achieved at the beginning of the rapid movement, regardless of the saw blade projection setting and whether the saw blade is pivoted, for example, for a miter cut.

[0018] The guide device for the circular saw provided according to the invention ensures that the rapid movement with which the circular saw blade is moved from the operating position to the safety position has, from the outset, a direction of movement that contributes to reducing the distance between a hand approaching the saw blade in the feed direction and the saw blade. It is particularly preferred if the direction of the rapid movement at the beginning of the rapid movement runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component running in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the rapid movement, and / or that the direction of the rapid movement from the starting point of the rapid movement to a point on the path of movement,which lies at 50% of the length of the movement path between the operating position and the safety position, runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the movement path of the fast movement in the first half of the movement path.

[0019] The rapid movement of the saw blade can, in principle, occur along a straight line or along a curved path, for example, by designing the guide device as a linear guide or as a pivot bearing. For the advantageous increase in distance achieved by this movement from the beginning of the rapid movement, as desired according to the invention, the angle that the direction of the rapid movement makes relative to the feed direction at the beginning of the rapid movement is an important influencing factor. The smaller this angle, the larger the directional component running along the feed direction, and correspondingly smaller the directional component of the rapid movement that lowers the saw blade, for example, below the workpiece support surface.For example, at an angle of 0°, the direction of the rapid movement would coincide with the feed direction; that is, the saw blade would only be moved away from a hand approaching in the feed direction, precisely in the feed direction, but would not initially be lowered into a safety position, such as one below the workpiece support surface. In this particular case, the safety position could therefore be a position of the circular saw blade offset from the feed direction.However, the rapid movement is usually performed with a direction that is initially or later in the movement at an angle to the feed direction, and in this case the saw blade axis is moved at the beginning of the rapid movement in a direction that has both or only a component that moves the saw blade axis away from the approaching hand in the feed direction and also a movement component that moves the saw blade axis perpendicular to this feed direction and consequently, for example, lowers it below the workpiece support surface.

[0020] The direction of the rapid movement can be the same for each adjustable saw blade projection and each adjustable pivoting of the saw blade for miter cuts, i.e. pivoting of the saw blade axis from the normal horizontal orientation for perpendicular cutting planes, which is particularly feasible if the adjustment of the saw blade projection and the miter angle pivoting of the saw blade is carried out by means of adjusting devices that are independent of the rapid movement device and the guide device and that are moved by or move along with this guide device itself.

[0021] In other embodiments, however, the adjustment of the saw blade projection can be integrally achieved by the rapid movement device and its guide device. In this case, the saw blade is guided completely or partially by the guide device during the adjustment of the saw blade projection. If the guide device does not ensure a linear direction for the rapid movement along its entire path, this can result in the direction of the rapid movement at the beginning of the rapid movement being dependent on the saw blade projection, i.e., differing for a first saw blade projection from a second. In this case, it is particularly preferred if the previously described preferred angles at which the rapid movement proceeds with respect to the feed direction are realized during a rapid movement of the saw blade from an operating position in which the saw blade is set to the maximum saw blade projection.This ensures that precisely when the risk of injury to the user is particularly high, namely with a large saw blade overhang, the desired increase in the distance between the hand approaching the saw blade in the feed direction is achieved from the very beginning through the rapid movement.

[0022] To achieve an effective distance between a hand approaching the saw blade in the feed direction and the saw blade itself, it is particularly preferred if, during the first half of the path between the operating position—especially the operating position with maximum blade projection—the saw blade is moved on average by the rapid movement in a direction that runs at an angle of less than 75° or 60°, and preferably less than 45°, to the feed direction. This ensures an effective proportion of the directional component in the feed direction over the first part of the guide path.In the case of a linear high-speed movement, this direction corresponds to the direction of the high-speed movement at every point on the guideway; in the case of a high-speed movement along a curved guideway, this direction corresponds to the direction of the connecting line between the starting point of the guideway and the point reached on the guideway after half the distance traveled between the operating position and the safety position; i.e., in the case of a guideway in the form of a circular segment, the secant between the starting point of the guideway and the point on the guideway reached after half the angle of the circular segment.

[0023] It is further preferred if the saw blade projects beyond the workpiece support surface in the operating position and the guide device is designed to guide the rapid movement as a rapid lowering of the saw blade below the workpiece support surface. The arrangement defined in this preferred embodiment corresponds to a typical table saw with a saw unit inserted into the machine table. The circular saw according to the invention can be designed, in particular, as such a table saw and especially as a panel saw; the advantages are particularly evident in these configurations.However, other circular saw arrangements are also conceivable, for example an arrangement similar to a miter saw with a saw unit arranged above the workpiece support surface, in which the circular saw blade is lowered onto the workpiece; in this case, the rapid movement can take place in a direction of movement that has a directional component that lifts the circular saw blade, in addition to the directional component that lies in the workpiece feed direction.

[0024] The preferred design, with the saw blade axis positioned below the workpiece support surface and a rapid lowering mechanism for the safety position, ensures that the saw blade is largely or completely retracted and therefore can no longer be touched by the user. A significant safety improvement is already achieved when the saw blade is lowered to the point where it is lowered relative to its operating position; often this is sufficient to ensure that the saw blade no longer protrudes from the workpiece and is therefore no longer accessible. A particularly safe rapid lowering mechanism for all operating conditions completely retracts the saw blade below the workpiece support surface, making it inaccessible to the user regardless of the presence of a workpiece.

[0025] It is further preferred if the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, along a path of movement which, over a section of movement comprising at least the first quarter, preferably the first third, of the total distance of the rapid movement from the operating position to the safety position, includes a directional component that runs in the feed direction. It is particularly preferred if the direction of the rapid movement over at least the first quarter, preferably the first third, of the rapid movement has a directional component that runs in the workpiece feed direction, in particular if the direction of the rapid movement over this portion of the path of the rapid movement runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction.This design of the direction of the rapid movement in the initial phase of the rapid movement achieves an advantageous additional distance between the approaching hand of the user and the circular saw blade, especially in this critical early phase of the safety measure.

[0026] In principle, the guide device can be designed to include a directional component in the feed direction over the entire portion of the movement path from the operating position to the safety position. However, it is particularly advantageous if such a movement component in the feed direction is present in the initial phase of the rapid movement and then decreases as the movement progresses. According to the inventors, this is because, as the speed of the circular saw blade increases, the angle between the tangent to the circumference of the circular saw blade and the feed direction at the danger point at the front end of the circular saw blade decreases. Consequently, as the rapid movement progresses, the danger point is also moved away from the approaching hand by a movement that propels the saw blade perpendicular to the feed direction.This effect is less pronounced at the beginning of the rapid movement, especially when the saw blade is set to a high blade projection. Therefore, it is generally preferable that the guide device be designed such that at the beginning of the rapid movement and in the first quarter or third of the movement, it exhibits a direction with a larger component of movement in the feed direction than at the end of the rapid movement or in the last third or quarter of the movement, where this component of movement in the feed direction can consequently be smaller, and conversely, a directional component perpendicular to the feed direction can be larger.

[0027] It is even more preferred if the guide device comprises a pivot lever which is pivotably mounted at one end on the machine frame about a pivot axis and connected at one end to the saw blade bearing. According to this embodiment, the guidance is effected by a pivot lever which is connected at one end to the saw blade bearing about the saw blade axis and at the other end to the machine frame. The pivot lever is pivotable about the machine frame about a pivot axis located at its first end, thus pivoting the saw blade bearing about this axis. In this case, the saw blade bearing is guided along a curved path, which in the simplest case can be a circular path around the pivot axis.In other configurations, where the pivot lever is supplemented by further movement possibilities (translational or again pivoting additional movements), the curved path can also be a different path of movement than the circular path.

[0028] It is particularly preferred if this embodiment is further developed by a saw blade drive device which comprises a drive force transmission by means of a first endless transmission element from a first transmission shaft rotatably mounted about the pivot axis to a saw blade shaft rotatably mounted about the saw blade axis, and which preferably comprises a drive motor which is attached to the machine frame and from which the drive force is transmitted to the saw blade by means of the first endless transmission element, in particular by means of a second endless transmission element from a motor shaft to the first transmission shaft.

[0029] This further development takes advantage of the fact that, when the saw blade bearing is guided on a pivot lever, the transmission of the drive force to the saw blade can advantageously be carried out by means of an endless transmission element such as a V-belt, multi-ribbed V-belt, toothed belt or a chain, which, if it provides a transmission between two deflection axes, one of which coincides with the pivot axis and the other with the axis bearing of the pivot lever on the saw blade bearing, in particular with the saw blade axis, this drive force transmission to the saw blade can be maintained during the entire guiding of the saw blade along the guide path.This is advantageous for transmitting a braking motion of the saw blade's rotation via such a continuous transmission element. This allows, for example, the saw blade to be decelerated by the drive motor, such as through a DC injection effected by the motor control or a motor braking force controlled by a frequency converter. Furthermore, this type of guide allows the saw blade to be moved along the guide track even when adjusting the blade projection, thus eliminating the need for an additional guide and adjustment mechanism for this projection beyond the rapid lowering mechanism. This is possible because, due to the transmission of the rotational force to the saw blade via a continuous transmission element running along the pivot lever, this rotational force transmission is possible in any position of the pivot lever.Mounting the drive motor to the machine frame and transmitting its driving force from the motor shaft to the saw blade via the first continuous transmission element, or optionally an additional intermediate second continuous transmission element, is advantageous because this allows the motor to remain stationary in the machine frame during high-speed movement and prevents it from moving with the movement. The mass to be accelerated during high-speed movement is therefore reduced by the mass of the drive motor, and consequently significantly lower. This results in a considerably lower force required for acceleration, allowing for a better and more cost-effective actuator design.The same acceleration of the saw blade can be achieved with a more cost-effective actuator and lower force as with a more expensive actuator that applies higher force, if in this case the drive motor also has to be accelerated.

[0030] In these embodiments with a pivot lever, it is further preferred if the pivot axis is arranged in a region that lies in front of a plane perpendicular to the workpiece support surface and encompassing the saw blade axis in the feed direction, and below a plane parallel to the workpiece support surface and encompassing the saw blade axis in the vertical direction. This region, which in a side view corresponds almost to a 90° angle range located at an angle to the workpiece support surface and in front of or within a perpendicular plane encompassing the saw blade axis in the feed direction, achieves a direction of rapid movement that already exhibits the desired directional component in the feed direction at the beginning of the rapid movement.The length of this directional component becomes greater relative to the overall length of the rapid movement direction the closer the pivot axis is to the plane perpendicular to the workpiece support surface and encompassing the saw blade axis, up to a position of the pivot axis in this plane where, at the start of the rapid movement, the saw blade moves exclusively in the feed direction. Conversely, arranging the pivot axis close to the plane parallel to the workpiece support surface results in a rapid movement direction that initially exhibits only a small proportion of a directional component in the feed direction. It should be understood that the position of the saw blade axis here refers at least to the position of the pivot axis when the saw blade projection is at its maximum setting, i.e., when the saw blade axis is in its uppermost position and has a minimum distance to the workpiece support surface.Especially in this position with maximum saw blade projection, the directional component in the feed direction is important for preventing injuries. Preferably, the pivot axis lies below a plane parallel to the workpiece support surface, in which the saw blade axis lies with a smaller saw blade projection – i.e., further away from the workpiece support surface. In this way, the advantageous horizontal directional component of the saw blade axis is achieved even with comparatively smaller saw blade projections, i.e., greater distances of the saw blade axis from the workpiece support surface. Particularly preferably, the pivot axis lies below a plane parallel to the workpiece support surface, in which the saw blade axis lies with a minimal saw blade projection – i.e., slightly less than the radius of the maximum usable saw blade from the workpiece support surface.

[0031] According to a further preferred embodiment, the circular saw according to the invention is further developed by a riving knife located behind the saw blade axis in the feed direction and connected to the high-speed movement device, which is designed to move the riving knife together with the saw blade axis. A riving knife is typically used to prevent the saw kerf already created in the workpiece from narrowing and thereby binding the saw blade. The riving knife therefore typically has a thickness that corresponds to the thickness of the cutting teeth of the saw blade or a thickness slightly greater. The riving knife is typically arranged behind the saw blade in the feed direction and surrounds the saw blade over a circumferential section above the workpiece support surface. The riving knife itself is typically arranged at a small distance from the circumference of the saw blade.

[0032] Prior devices perform a rapid movement in which the riving knife remains stationary, thus advantageously eliminating the need to accelerate the mass of the riving knife. However, in the inventive embodiment of the rapid movement with a directional component extending in the feed direction, the distance between the circular saw blade and the riving knife is reduced from the outset, creating a risk of the saw blade coming into contact with the riving knife. Such contact is undesirable, as it would damage both the riving knife and the saw blade. Therefore, according to the invention, it is preferred for the riving knife to move together with the saw blade axis during the rapid movement.

[0033] This combined movement need not be synchronous, in the same direction, or at the same speed. However, the combined movement of the saw blade axis and the riving knife must be such that both the saw blade axis and the riving knife move during the rapid movement. The start of the riving knife's movement can coincide with the start of the saw blade's movement, or it can precede or follow it. The riving knife can move in the same direction as the saw blade axis, thereby maintaining a constant distance between the riving knife and the saw blade circumference, provided the movement speeds are also identical.The movement of the riving knife can also occur in a different direction, for example, such that it is guided in such a way that it is extended by a predetermined amount in the feed direction by a safety distance, and this safety distance prevents the saw blade from coming into contact with the riving knife during its rapid movement. The movement of the riving knife can, in particular, be guided by the same guide device as the movement of the saw blade.

[0034] According to a further preferred embodiment, the rapid movement device comprises a height actuator and an electronic control device for controlling the height actuator, wherein the electronic control device is configured to drive the height actuator in a safety mode upon receiving the hazard signal for rapid movement, and the height actuator is configured to move the saw blade axis in safety mode from any operating position to the safety position within a time span of less than 0.5 seconds, and wherein the electronic control device is configured to drive the height actuator in a protrusion mode upon receiving an overhang signal, and the height actuator is configured to drive the saw blade axis in overhang mode by a positional displacement of the saw blade axis encoded by the overhang signal with a tolerance of at most 0.5 mm.According to this embodiment, the high-speed movement device includes a height actuator that can be controlled bifunctionally. In a safety mode, the control device and the height actuator are configured and interact in such a way that a rapid movement of the saw blade is executed, moving it quickly from the operating position to the safety position with a high degree of positioning accuracy, which is not required in this mode. In the overhang mode, however, the control devices and the height actuator are configured and interact in such a way that the saw blade is set to a predetermined overhang, typically entered via an electronic user interface, with high positioning accuracy.In this overhang mode, rapid saw blade movement is not critical; instead, positioning accuracy is of particular importance, for example, when the saw blade is to cut a groove of a specific depth into the workpiece. In such an application, the dimensional accuracy of the groove depth is determined by the positioning accuracy of the saw blade overhang. Advantageously, this embodiment utilizes a single height actuator that can be used for the two essential functions and movement modes of the saw blade.This design is particularly favored by the saw blade guidance according to the invention, since, due to the advantageous gain in distance resulting from this guidance during rapid movement, the height actuator can be designed with a reduced drive power compared to the prior art, and consequently, height actuators can be used whose design characteristics can forgo particularly high power and travel speed in favor of positioning accuracy.

[0035] This advanced training eliminates the need for a special mechanism for adjusting the saw blade projection. Instead, both the guide device and the height actuator can be used to adjust the saw blade projection, thus simplifying the movement mechanism between the machine frame and the saw blade, making it more cost-effective and robust.

[0036] It is further preferred if the electronic control device has a user interface for entering a saw blade projection value and is configured to control the height actuator in projection mode depending on the saw blade projection, wherein the control device is further configured to deactivate projection mode in favor of prioritizing safety mode upon receiving a hazard signal. According to this embodiment, the saw blade projection desired by the user for machining the workpiece can be entered via an electronic interface, for example, a keypad, and then the saw blade is adjusted to the entered projection by the height actuator.It is provided that, for safety reasons, the control device may over-regulate the operation for adjusting the saw blade projection by quickly moving the saw blade into the safety position, in order to avoid any risk of injury to the user in the event of a hazardous situation being detected, even if the saw blade is currently being adjusted in projection mode.

[0037] It is even more preferred if the hazard detection device includes an image acquisition and evaluation device designed to detect a hazardous situation by means of image evaluation with body part recognition in successive image acquisitions of a hazard area. According to this advanced training, hazard detection is carried out by means of image recognition and image evaluation in which successive image acquisitions of a hazard area, which can typically include the saw blade, and typically alternatively or additionally an area located in front of the saw blade in the feed direction, are monitored and are able to distinguish body parts, such as hands, located in this area from the surroundings and other objects, and therefore determine their position, movement, and acceleration.Based on this detection of the hand's position, speed, acceleration, direction of movement, and acceleration direction, it is possible to predict whether the hand would come into contact with the saw blade's circumference within a trigger period and generate a hazard signal from this prediction. In particular, the hazard detection device can be linked to the control device for adjusting the saw blade projection via a signal connection. The device receives the saw blade projection and, if applicable, the saw blade diameter from the control device and incorporates this information into a calculation of the necessary lead time for a rapid movement of the circular saw blade to prevent injury.This allows the time interval between the sending of the hazard signal and the contact between the hand and the saw blade circumference determined in the forecast to be individually adjusted to the saw blade protrusion and the time required for a quick movement from this operating position to the safety position.

[0038] Another aspect of the invention is a method for preventing injuries on circular saws, comprising the following steps: rotating a saw blade arranged on a saw unit around a saw blade axis, feeding a workpiece in a feed direction that preferably runs parallel to the workpiece support surface and perpendicular to the saw blade axis, detecting a hazardous situation involving a user's body part being endangered by the saw blade by means of an electronic hazard detection device of a safety device, transmitting a hazard signal from the hazard detection device to a rapid movement device of the safety device, and rapidly moving the saw blade upon receiving the hazard signal from an operating position to a safety position in which the saw blade poses less of a risk to the user's body part than in the operating position, in particular not at all.wherein the rapid movement of the saw blade by means of a guide device for guiding the saw blade from the operating position to the safety position is guided, at least at the beginning of the rapid movement, on a movement path which includes, at least at the beginning of the rapid movement, a directional component that runs in the feed direction, and / or that the rapid movement from the starting point of the rapid movement to a point on the movement path which lies at 50% of the length of the movement path between the operating position and the safety position, is guided on a movement path (FB) which includes a directional component that runs in the feed direction.

[0039] The method according to the invention is particularly suitable for use with the circular saw according to the invention as described above. It serves to reliably and cost-effectively prevent injuries to body parts when using a circular saw. A key feature of the method according to the invention, in accordance with the specific guide device of the circular saw described above, is that, in the event of a hazardous situation, the circular saw blade is moved from its operating position to a safe position in such a way that the movement of the circular saw blade, at least initially, has a directional component that extends towards the saw blade in the direction in which the workpiece is fed.

[0040] The method can be further developed in which the saw blade is adjustable by means of a saw blade projection adjustment device to an operating position with maximum saw blade projection and is moved from this operating position with maximum saw blade projection to the safety position, at least at the beginning of the rapid movement, along the rapid movement direction, which includes a directional component running in the feed direction. Furthermore, it is preferably provided that the rapid movement direction at the beginning of the rapid movement runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component running in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the rapid movement, and / or that the direction of the rapid movement from the starting point of the rapid movement to a point on the path of movement,which lies at 50% of the length of the movement path between the operating position and the safety position, runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component running in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the movement path of the fast movement in the first half of the movement path, and / or the saw blade is guided from the operating position, in particular from each operating position, on a movement path which includes a directional component running in the feed direction for a movement section of at least the first quarter, preferably the first third of the total distance of the fast movement of the height actuator from the operating position to the safety position.

[0041] Furthermore, it is advantageously provided that a saw blade projection is entered via an electronic user interface of a control device, and the saw blade is adjusted to an operating position with this entered saw blade projection, with a tolerance of at most 0.5 mm, by means of a height actuator controlled by the control device of a saw blade projection adjustment device, and, upon transmission of the hazard signal, is moved from this operating position to the safety position by means of the height actuator within a period of less than 0.5 seconds. Regarding this further development of the method according to the invention, the variants and technical advantages of this further development, reference is made to the preceding description of the analogous further developments of the circular saw according to the invention.

[0042] Finally, another aspect of the invention is the use of a rapid movement device for rapidly moving a circular saw blade from an operating position to a safety position after receiving a hazard signal indicating a danger to a user's body part, in such a way that the rapid movement of the saw blade from the operating position to the safety position is guided, at least at the beginning of the rapid movement, preferably along at least the first quarter of the total distance of the rapid movement, along a rapid movement direction which includes a directional component that runs in a feed direction along which the workpiece is fed to the saw blade, wherein preferably the rapid movement direction at the beginning of the rapid movement runs at an angle of less than 75°, in particular less than 45°, to the feed direction, such that the portion of the directional component that runs in the feed direction,at least 25.88%, in particular at least 70.71%, of the rapid movement, and / or that the direction of the rapid movement from the starting point of the rapid movement to a point on the path of movement located at 50% of the length of the path of movement between the operating position and the safety position runs at an angle of less than 75°, in particular less than 60°, and preferably less than 45°, to the feed direction, such that the proportion of the directional component running in the feed direction in the first half of the path of movement is at least 25.88%, in particular at least 50%, and preferably at least 70.71% of the path of movement of the rapid movement. The use can be advantageously further developed,in which a saw blade projection can be entered via an electronic user interface of a control device and the saw blade can be adjusted to an operating position with this entered saw blade projection with a tolerance of at most 0.5 mm by means of a height actuator of a saw blade projection adjustment device controlled by the control device, and can be moved from this operating position to the safety position by means of the height actuator within a period of less than 0.5 seconds when the danger signal is transmitted.

[0043] Regarding these uses, which can be carried out in particular with the previously explained rapid movement device of the circular saw, reference is made to the preceding description of the analogous device properties and features with regard to the advantages, possible variants and functions that arise.

[0044] A preferred embodiment is explained with reference to the accompanying figures. These show:

[0045] Fig. 1a shows a schematic section view of a saw blade in an operating position and a partially lowered position in a vertical lowering movement.

[0046] Fig. 1b shows a representation according to Figure 1a with an oblique lowering movement of the saw blade,

[0047] Fig. 2 shows a schematic representation of the kinematics of a device according to the invention.

[0048] Device for quickly lowering a circular saw blade of a circular saw,

[0049] Fig. 3a shows the blade projection, distance to the danger point, acceleration and speed of a saw blade during a vertical rapid movement into the safety position.

[0050] Fig. 3b shows a representation according to Figure 3a during a rapid oblique movement into the safety position,

[0051] Fig. 4 shows a schematic side view of an embodiment of the circular saw according to the invention, and

[0052] Fig. 5 shows a perspective overall view of an embodiment of the circular saw according to the invention. As can initially be seen from Figure 1a, during a rapid movement SB of the saw blade from an operating position 10a to a lowered position 10b, which can be the position between the operating position and the safety position, a distance D1 is created between a danger point in the operating position Ga and a danger position in the lowered position Gb.This safety distance D1 results solely from the fact that the tangent of the circular saw blade circumference at the danger point Ga runs obliquely to the workpiece support surface WA, and that the circular saw blade naturally tapers upwards due to its circular circumference. This means that the intersection point Gb of the saw blade circumference with the workpiece support surface in the lowered position 10b is offset from the intersection point Ga of the saw blade circumference with the workpiece support surface in the operating position 10a in the feed direction Z of the workpiece. S denotes the cutting movement of the saw blade.

[0053] While this small offset D1 is advantageous for slightly increasing the distance between a hand approaching in the feed direction Z and the saw blade circumference, it is insufficient to achieve an effective power reduction for a sufficiently rapid lowering of the saw blade in a hazardous situation. Furthermore, particularly when the saw blade overhang SU above the workpiece support surface WA is especially large, the angle at which the tangent at the hazard point Ga to the workpiece support surface approaches 90°, and the tapering of the saw blade in the initial range of its lowering movement is very slight, resulting in a very small safety distance D1 in this case.

[0054] Figure 1b shows the same situation: a lowering movement of the saw blade from an operating position 10'a to a lowered position 10'b with a rapid, oblique downward movement that has a directional component SB'z in the feed direction. It can be seen that this lowering movement achieves a greater safety distance D2 between the hazard point G'b and the hazard point G'a, and consequently a greater distance is gained between the hand approaching in the feed direction Z and the saw blade.

[0055] Figure 2 shows an advantageous kinematic design of a guide device according to the invention for the rapid lowering of a saw blade in a hazardous situation. The saw blade 110 is rotatably mounted about a saw blade axis 111 and rotates with a cutting motion S, while a workpiece is fed in a feed direction Z. A hazard point G is created at the intersection of the saw blade circumference with a workpiece support surface WA. The saw blade axis 111 is pivotably mounted on a pivot lever 120 about a pivot axis 121. This pivot lever 120 guides the saw blade axis 111 on a guide track FB of the rapid movement SB. In this case, the guide track is a circular segment.In this side view of the kinematics, the pivot axis 121 lies in a segment Q that spans an angular range slightly below the horizontal plane in which the saw blade axis 111 lies at maximum saw blade projection SU, and a plane that is perpendicular and encloses the saw blade axis. A pivot axis located in this range Q ensures the preferential guidance of the saw blade axis on a guide track FB during the rapid movement, which at the start has a directional component SB"z running in the feed direction Z.

[0056] The saw blade is driven by means of a V-ribbed belt 122, which is deflected on the pivot axis 121 on one side and the saw blade axis 111 on the other. Another V-ribbed belt is tensioned between the pivot axis 121 and a motor shaft 131 of a saw blade drive motor 130 and transmits the drive force from a saw blade drive motor 130, which is fixed in place in the machine frame, to the pivot axis.

[0057] The safety position 110b of the saw blade is identifiable in the broken lines, in which the danger point G“b is offset by a considerable amount in the feed direction compared to the danger point G“a in the operating position. This amount is composed of an offset that is created by the tapering of the saw blade in the vertical direction and the directional component SB“z.

[0058] Figure 3a shows a simulation of a rapid lowering of a saw blade by 200 millimeters in 100 milliseconds. The left vertical axis A is defined by the saw blade projection [mm] / the distance of the danger point [mm] n / the acceleration [m / s²]. 2 ) labelled, the horizontal axis B is labelled with the time [ms] and the right vertical axis C is labelled with the speed of the lowering movement [m / s].

[0059] This simulation is calculated to simulate a hand approaching at a speed of 2 m / s, its position represented by a dashed line L1. The saw blade's movement is designed to prevent any contact between the hand and the blade. The saw blade is lowered from an initial overhang of 105 mm, represented by line L2. The horizontal position of the point of danger is represented by line L3; it is initially 148 mm and decreases due to the tapering of the saw blade during the lowering motion. As can be seen from the simulation, a high acceleration L5 of 20 m / s² is required to avoid this potentially damaging contact. 2 necessary, which accelerates the saw blade to a maximum speed L4 of approximately 1.10 meters per second.

[0060] Figure 3b shows the same simulation for a lowering of the saw blade in a downward-sloping guide path, which contains a directional component in the feed direction from the beginning and throughout the entire movement. Again, the movement is calculated so that no injury-causing contact occurs between the hand and the saw blade. The position L3' of the danger point moves more rapidly in the feed direction during the critical initial phase than in the purely vertical lowering according to Fig. 3a, whose danger point position L3 is shown in Fig. 3b for comparison. As can be seen, with this guide path for the saw blade, the maximum acceleration L5' is approximately 18 m / s². 2This is required, and the saw blade is accelerated to a maximum speed L4' of approximately 0.98 m / s. Therefore, a significantly lower force is needed to achieve this acceleration and speed, and the actuator required to achieve this force and speed can have more favorable specifications and thus be selected in a cost-effective manner.

[0061] Figures 4 and 5 show an embodiment of the circular saw according to the invention. A circular saw blade 210 is rotatably mounted about a saw blade axis 211 arranged below a workpiece support surface WA and projects upwards through a saw slot above the workpiece support surface by a saw blade overhang SU.

[0062] The saw blade axis 21 1 is pivotably mounted on a pivot lever 220 about a pivot axis 221. The saw blade is driven by a saw blade drive motor 230 via V-ribbed belts 222, 232.

[0063] A height actuator 240 in the form of a servo spindle drive is attached at its lower end to the frame 200 of the circular saw and coupled at its upper end to the saw blade axis. The height actuator can be controlled by a controller 250 to adjust the saw blade projection with an accuracy of 0.1 mm.

[0064] The control unit 250 is signal-linked to an image acquisition device 260, which captures images of a danger zone 261. From the image data, the control unit can calculate the detection of a hand moving within the image acquisition zone with regard to its position, direction of movement, speed, direction of acceleration, and acceleration. From this, it determines when the hand would reach a point of contact with the saw blade. Depending on further data, such as the size of the saw blade and the set saw blade projection, a time safety interval is calculated. If the expected time until the hand contacts the saw blade approaches this time safety interval within a predetermined time range, a danger signal is generated. The control unit 250 then activates the saw blade drive motor for rapid braking and the height actuator for rapid lowering at up to 1 m / s (at maximum saw blade projection).

Claims

1. Claims 1. Circular saw comprising: a machine frame (200), a workpiece support surface (WA) connected to the machine frame, a saw unit movably guided in the machine frame, a saw blade bearing arranged on the saw unit for rotatable bearing of a saw blade (210) about a saw blade axis (11;211), a safety device for rapid movement of the saw blade in a hazardous situation, comprising a hazard detection device (250, 260) configured to detect a hazard to a user's body part from the saw blade and to generate a hazard signal upon detection of a hazard, and a rapid movement device (240) which is connected to the hazard detection device for receiving the hazard signal and is configured to move the saw blade rapidly from an operating position (10a') to a safety position (10b') upon receiving a hazard signal, in which the saw blade poses less of a hazard to the user's body part than in the operating position, in particular not at all, wherein a feed direction (Z) is defined by the workpiece support surface and the saw blade axis, which is parallel to the workpiece support surface (WA) and perpendicular to the saw blade axis (11;211) is characterized in that the rapid movement device has a guide device (220, 221) for guiding the saw blade axis from the operating position (10a') to the safety position (10b'), and that the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, on a movement path (FB) which includes, at least at the beginning of the rapid movement, a directional component (SB“z) which runs in the feed direction (Z), and / or that the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, on a movement path (FB) on which the direction of the rapid movement; from the starting point of the rapid movement to a point on the movement path that lies at 50% of the length of the movement path between the operating position and the safety position, includes a directional component that runs in the feed direction.

2. Circular saw according to claim 1, characterized in that the direction of the rapid movement at the beginning of the rapid movement is at an angle (β1) of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the path of motion of the rapid movement, and / or that the direction of the rapid movement from the starting point of the rapid movement to a point on the path of motion that lies at 50% of the length of the path of motion between the operating position and the safety position is at an angle (β2) of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88% in the first half of the path of motion.in particular at least 50% and preferably at least 70.71% of the path of the rapid movement.

3. Circular saw according to claim 1 or 2, characterized in that the saw blade projects beyond the workpiece support surface in the operating position and the guide device is designed to guide the rapid movement as a rapid lowering of the saw blade below the workpiece support surface.

4. Circular saw according to one of the preceding claims, characterized in that the guide device is designed to guide the saw blade axis from the operating position, in particular from any operating position, on a movement path which includes a directional component (SB“z) extending in the feed direction over a movement section of at least the first quarter, preferably the first third of the total distance of the rapid movement from the operating position to the safety position.

5. Circular saw according to one of the preceding claims, characterized in that the guide device comprises a pivot lever (220) which is pivotably mounted at a first end on the machine frame about a pivot axis (221) and is connected at a second end to the saw blade bearing.

6. Circular saw according to claim 5, characterized by a saw blade drive device comprising a drive force transmission by means of a first endless transmission element (222) from a first transmission shaft rotatably mounted about the pivot axis (221) to a saw blade shaft rotatably mounted about the saw blade axis, and which preferably comprises a drive motor (230) which is attached to the machine frame (200) and from which the drive force is transmitted to the saw blade by means of the first endless transmission element, in particular by means of a second endless transmission element (232) from a motor shaft to the first transmission shaft.

7. Circular saw according to claim 5 or 6, characterized in that the pivot axis is arranged in a region (Q) which lies in the feed direction in front of a plane perpendicular to the workpiece support surface and including the saw blade axis and in the vertical direction below a plane parallel to the workpiece support surface and including the saw blade axis.

8. Circular saw according to one of the preceding claims, characterized by a riving knife located behind the saw blade axis in the feed direction and connected to the rapid movement device designed to move the riving knife together with the saw blade axis.

9. Circular saw according to one of the preceding claims, characterized in that the rapid movement device comprises a height actuator and an electronic control device for controlling the height actuator, wherein the electronic control device is configured to drive the height actuator in a safety mode upon receipt of the hazard signal for rapid movement, and the height actuator is configured to move the saw blade axis in safety mode from any operating position to the safety position within a time span of less than 0.5 seconds, and wherein the electronic control device is configured to drive the height actuator in a protrusion mode upon receipt of an overhang signal, and the height actuator is configured to Saw blade axis in overhang mode to control a positional shift of the saw blade axis encoded by the overhang signal with a tolerance of at most 0.5mm.

10. Circular saw according to claim 9, characterized in that the electronic control device, which has a user interface for inputting a saw blade overhang value and is designed to control the height actuator depending on the saw blade overhang in overhang mode, wherein the control device is further designed to switch off the overhang mode in favor of prioritizing the safety mode upon receipt of a hazard signal.

11. Circular saw according to one of the preceding claims, characterized in that the hazard detection device comprises an image acquisition and evaluation device which is designed to detect a hazardous situation by means of an image evaluation with body part recognition in successive image acquisitions of a hazard area.

12. Procedures for injury prevention on circular saws, comprising the following steps: Rotation of a saw blade mounted on a saw unit around a saw blade axis, Feeding a workpiece in a feed direction that preferably runs parallel to the workpiece support surface and perpendicular to the saw blade axis, Detecting a hazardous situation involving a user's body part and the saw blade using an electronic hazard detection device or safety device. Transmission of a hazard signal from the hazard detection device to a rapid movement device of the safety device, Rapid movement of the saw blade upon receipt of a hazard signal, with a rapid movement from an operating position to a safety position in which the saw blade poses less of a risk to the user's body part than in the operating position, in particular not at all, characterized in that the rapid movement of the saw blade is guided, at least at the beginning of the rapid movement, by means of a guide device for guiding the saw blade from the operating position to the safety position, on a movement path (FB) which includes, at least at the beginning of the rapid movement, a directional component (SB“z) which runs in the feed direction (Z), and / or that the rapid movement from the starting point of the rapid movement to a point on the movement path which lies at 50% of the length of the movement path between the operating position and the safety position, on a The motion path (FB) is guided, which includes a directional component that runs in the feed direction.

13. Method according to claim 12, characterized in that the saw blade is adjustable by means of a saw blade projection adjustment device into an operating position with maximum saw blade projection and is guided from this operating position with maximum saw blade projection into the safety position at least at the beginning of the rapid movement along the rapid movement direction, which includes a directional component that runs in the feed direction.

14. Method according to claim 12 or 13, characterized in that the direction of rapid movement at the beginning of the rapid movement is at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the path of motion of the rapid movement, and / or that the direction of the rapid movement from the starting point of the rapid movement to a point on the path of motion that lies at 50% of the length of the path of motion between the operating position and the safety position is at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88% in the first half of the path of motion.in particular at least 50% and preferably at least 70.71% of the path of movement of the fast movement, and / or the saw blade is guided from the operating position, in particular from any operating position, on a path of movement which includes a directional component running in the feed direction over a movement section of at least the first quarter, preferably the first third of the total distance of the fast movement as height actuator from the operating position to the safety position, 15. Method according to one of claims 12 to 14, characterized in that a saw blade projection is entered via an electronic user interface of a control device and the saw blade is set into an operating position with this entered saw blade projection with a tolerance of at most 0.5 mm by means of a height actuator of a saw blade projection adjustment device controlled by the control device, and is moved from this operating position to the safety position by means of the height actuator within a period of less than 0.5 seconds when the danger signal is transmitted.

16. Use of a rapid movement device for rapidly moving a circular saw blade from an operating position to a safety position after receiving a hazard signal indicating a hazard to a user's body part, in such a way that the rapid movement of the saw blade from the operating position to the safety position is guided, at least at the beginning of the rapid movement, preferably along at least the first quarter of the total distance of the rapid movement, along a rapid movement direction which includes a directional component that runs in a feed direction along which the workpiece is fed to the saw blade, wherein preferably the rapid movement direction at the beginning of the rapid movement runs at an angle of less than 75°, in particular less than 45°, to the feed direction, such that the proportion of the directional component that runs in the feed direction is at least 25.88%, in particular at least 70%.71% of the trajectory of the rapid movement, and / or the direction of the rapid movement from the starting point of the rapid movement to a point on the trajectory located at 50% of the length of the trajectory between the operating position and the safety position runs at an angle of less than 75°, in particular less than 60° and preferably less than 45° to the feed direction, such that the proportion of the directional component running in the feed direction is at least 25.88%, in particular at least 50% and preferably at least 70.71% of the trajectory of the rapid movement in the first half of the trajectory.

17. Use according to claim 16, characterized in that a saw blade projection can be entered via an electronic user interface of a control device and the saw blade can be adjusted to an operating position with this entered saw blade projection with a tolerance of at most 0.5 mm by means of a height actuator of a saw blade projection adjustment device controlled by the control device, and can be moved from this operating position to the safety position within a period of less than 0.5 seconds when the danger signal is transmitted by means of the height actuator.

Images