SHIELDING DEVICE FOR A SAW, IN PARTICULAR A TABLE SAW, AND SAW EQUIPPED WITH SUCH A SHIELDING DEVICE, IN PARTICULAR A TABLE SAW

Abstract

The invention is concerned with a shielding device (1) for shielding a saw blade (3) or band of a sawing machine against access by an operator and against ejection of workpiece parts, which can be attached to the sawing machine in such a way that, in a working position, it covers the saw blade (3) or band towards the operator. The shielding device (1) comprises a temperature monitoring unit (2) which has a temperature sensor (4).

The invention is characterized in that the temperature sensor (4) operates without contact and, with the shielding device (1) mounted on the sawing machine and located in the working position, is directed towards the toothing of the saw blade (3) or band, and a display device (5) displays the surface temperature detected by the temperature sensor (4) on the surface of the toothing of the saw blade (3), wherein the temperature monitoring unit (2) is formed as an autarkic operating unit and is mounted on the shielding device (1) such that it is detachable by an operator without tools.

The invention is further concerned with a sawing machine with such a shielding device (1).

Claims

1. A shielding device (1) for shielding a saw blade (3) or band of a sawing machine against access by an operator and against ejection of workpiece parts, which can be attached to the sawing machine in such a way that, in a working position, it covers the saw blade (3) or band towards the operator, the shielding device (1) comprising a temperature monitoring unit (2) which has a temperature sensor (4), wherein the temperature sensor (4) operates without contact and, with the shielding device (1) mounted on the sawing machine and located in the working position, is directed towards the toothing of the saw blade (3) or band, and a display device (5) displays the surface temperature detected by the temperature sensor (4) on the surface of the toothing of the saw blade (3), wherein the temperature monitoring unit (2) is formed as an autarkic operating unit and is mounted on the shielding device (1) such that it is detachable by an operator without tools.

2. The shielding device (1) according to claim 1, wherein the shielding device (1) is formed as a saw blade guard (1) mountable above a table of a circular table saw.

3. The shielding device (1) according to claim 1, wherein the temperature monitoring unit (2) is battery or accumulator-operated and comprises a battery compartment, which is preferably accessible via a removable cover (8), for accommodating batteries (6) or accumulators.

4. The shielding device (1) according to claim 3, wherein the temperature monitoring unit (2) has an ON/OFF switch at which it can be switched ON or OFF by an operator.

5. The shielding device (1) according claim 4, wherein the temperature monitoring unit (2) comprises a microcontroller wherein control routines for controlling the temperature monitoring unit (2) are implemented so that, when the temperature monitoring unit (2) is switched on, the detected surface temperature is displayed on the display device (5) in response to the output of the temperature sensor (4).

6. The shielding device (1) according to claim 1, wherein the display device (5) is formed as an OLED display.

7. The shielding device (1) according to claim 6, wherein the temperature sensor (4) is formed as an infrared temperature sensor (4).

8. The shielding device (1) according claim 1, wherein the temperature monitoring unit (2) has a cutting line display device (9) which is formed in particular as a laser diode (9) with refractive optics projecting a line pointing in the cutting direction onto the workpiece.

9. The shielding device (1) according to claim 2, wherein the temperature monitoring unit (2) is pushed or clipped onto the shielding device (1).

10. The shielding device (1) according to claim 8, wherein the temperature monitoring unit (2) comprises a targeting aid device (10) which emits, in the direction of detection of the temperature sensor, a light beam which is point-shaped in cross-section, for targeting a measuring point whose surface temperature is to be measured with the removed temperature monitoring unit (2), in particular a targeting aid device (10) in the form of a laser diode (10) with a convex lens.

11. The shielding device (1) according to claim 2, wherein the shielding device (1) has a holder section able to be fixedly attached to the sawing machine and a shield carrier section which is movably accommodated thereon, in particular pivotably, so that the shielding device (1) can be attached to the sawing machine movably, in particular pivotably, between an open position in which the saw blade (3) lies open and the working position covering the saw blade (3).

12. The shielding device (1) according to claim 11, wherein the temperature sensor (4) is directed, with the shielding device (1) mounted on the sawing machine and located in the working position, towards that surface of the toothing of the saw blade (3) or band that is running transversely to the cutting direction, in particular on the circumferential side of the saw blade (3).

13. A sawing machine having a saw blade (3) or band to which a shielding device (1) covering the saw blade (3) or band is attached for shielding the saw blade (3) or band against access to and ejection of workpiece parts, wherein the shielding device (1) is formed according to one of the preceding claims.

14. The sawing machine according to claim 13, wherein the sawing machine is constructed as a circular table saw with a machine table penetrated by a saw blade (3) at a slot-shaped recess, to which machine table a shielding device (1) formed as saw blade guard (1) is attached above the saw blade (3), the shielding device (1) attached to the sawing machine in such a way that, in a working position, it covers the saw blade (3) or band towards the operator, the shielding device (1) comprising a temperature monitoring unit (2) which has a temperature sensor (4) wherein the temperature sensor (4) operates without contact and, with the shielding device (1) mounted on the sawing machine and located in the working position, is directed towards the toothing of the saw blade (3) or band, and a display device (5) displays the surface temperature detected by the temperature sensor (4) on the surface of the toothing of the saw blade (3), wherein the temperature monitoring unit (2) is formed as an autarkic operating unit and is mounted on the shielding device (1) such that it is detachable by an operator without tools.

Description

[0029] In the following, a preferred embodiment of the invention is explained in more detail on the basis of the enclosed drawings.

[0030] FIG. 1 shows a perspective view of an embodiment of the shielding device according to the invention in working position above a circular saw blade, formed as a saw blade guard for a circular saw;

[0031] FIG. 2 shows a view corresponding to FIG. 1 with the temperature monitoring unit of the shielding device removed;

[0032] FIG. 3 shows detail III from FIG. 1 omitting the side walls of the shielding device;

[0033] FIG. 4 shows a detail according to a variant of the embodiment of the invention shown in FIGS. 1 to 3; and

[0034] FIG. 5 shows an electrical circuit diagram of the temperature monitoring unit of the shielding device in the variant according to FIG. 4.

[0035] First, reference is made to FIG. 1, which shows a shielding device 1 in its working position above a saw blade 3 of a circular saw, which is designed as a saw blade guard or saw blade cover, and whose further details have been omitted here for reasons of clarity. The saw blade guard 1 has a roughly hood-shaped form and carries a temperature monitoring unit 2 on its upwardly directed end face, which, in principle, but without going closer into the technically known fasteners, is shown in FIG. 2.

[0036] FIG. 3 shows the details of temperature monitoring unit 2 of shielding device 1. One can see an infrared temperature sensor designated by reference sign 4, which is directed towards or which is pointing to the circumferential surface of the toothing of the saw blade 3 with an opening angle of 10 and which detects the temperature prevailing there. The measurement results obtained are processed in a non-displayed microcontroller unit and are displayed on a display device 5 formed as an OLED display, if the temperature monitoring unit 2 has been switched on at an ON/OFF switch button 7. The energy required to operate the temperature monitoring unit 2 is supplied by two AAA battery cells 6 inserted in a battery compartment. The battery compartment is accessible via a removable cover 8. The temperature monitoring unit 2 thus operates completely independently and can also, as FIG. 2 shows, be removed from the shielding device 1 and used as an independent surface thermometer. In addition to the temperature of a remote object, the sensor can also measure the ambient temperature.

[0037] FIG. 4 shows a further development of the temperature monitoring unit 2 shown in FIGS. 1 to 3 with two additional laser diodes 9, 10 above the saw blade 3 in position adjacent to the IR temperature sensor 4, but omitting all other components. The laser diode 9 points in the cutting direction and is equipped with refractive optics so that it projects a line pointing in the cutting direction onto the workpiece section in front of the saw blade 3 and thus functions as a cutting line display. The laser diode 10, on the other hand, serves as a bearing aid if the user wants to use the removed temperature monitoring unit 2 as an independent IR thermometer and points in the same direction as the IR temperature sensor 4. To bundle the laser beam of the laser diode 10, it can be equipped with a convex lens.

[0038] FIG. 5 shows the electronics of the temperature monitoring unit further developed according to FIG. 4, wherein partially deviating reference characters have been used for the individual elements in the circuit diagram context.

[0039] The sensor transmits the measurement result via I2C bus to the microcontroller MCU1. The entire electronic circuit is powered by two AAA batteries B1 to keep the dimensions small. The circuit is put into operation via the on/off switch SW1. The step-up DC-DC converter U1 converts the voltage of 3 V, provided by the two AAA batteries B1 connected in series, into regulated 5 V, which is required for the temperature sensor U1 and the microcontroller MCU1. The converter U1 requires only four external components: the two electrolytic capacitors C1 and C2 as well as the choke L1 and the diode D1. The I2C bus has two pull-up resistors R1 and R2. The C3 ceramic capacitor is used for decoupling.

[0040] D5 and D6 are laser diodes. The threshold voltage of the series-connected diodes D2, D3 and D4 provides a voltage drop of approx. 2.1 V, so that a supply voltage of approx. 2.9 V is given for the two laser diodes D5 and D6. The logic-level-N-channel MOSFETs Q1 and Q2 pull the cathodes of the laser diodes D5 and D6 to ground when 5 V is applied to their gates. The laser diode D5 has a convex lens so that a point-shaped laser beam emerges. The laser diode D6 has a refractive optics, so that a linear laser beam emerges. The laser diode D5 serves as a targeting aid in order to target an object whose temperature is to be determined when the temperature monitoring unit is removed from the saw blade guard 1 and serves as an IR thermometer. The laser diode D6 serves as a cutting line display when the temperature monitoring unit is located on the saw blade guard 1 and the temperature of the saw blade 3 is to be determined.

[0041] In order to ensure good legibility even over a greater distance and in the case of poor lighting conditions, the OLED display DSP1 is used. Data between the OLED display DSP1 and the microcontroller MCU1 are transmitted via SPI or also via the I2C bus. The SW2 button can be used to select various functions. These include at least switching from line laser operation to point laser operation and vice versa, displaying the ambient and saw blade temperature in C. and F. with acoustic warning by the piezo transducer P1 and optical warning by corresponding warning texts or warning symbols on the OLED DSP1 in case of overheating of the saw blade, a timer indicating on the OLED DSP1 the time, which has elapsed since the circuit has been set into operation, further the display of the average ambient and saw blade temperature in C. and F., which is calculated from the stored measured values of the temperature sensor and the elapsed time since the circuit has been set into operation, as well as a display on the OLED DSP1 on the state of charge of the batteries B1 and the rotation of the displayed text or symbols by 180.

[0042] The B1 batteries are accessible for replacement via the battery cover 1. The OLED DSP1 is mounted on the saw blade guard at an angle clearly readable for the user of the machine during operation. The SW1 on/off switch or SW2 button is located in front of the battery cover 1. The temperature sensor U2 is located on the underside of unit A and points to tooth 3 of the saw blade 4 via a recess in the saw blade guard 2.

[0043] Deviations and modifications from the embodiments shown are possible without leaving the scope of the invention.