Handheld, hand-guided cutting-off machine

Abstract

A handheld, hand-guided cutting-off machine (10), which includes a rotating cutting-off wheel, a supporting housing part (36), an output shaft, which is rotatably supported around an output axis (40), a drive motor, a transmission mechanism (19), which connects the drive motor to the output shaft, a flange and a safety guard (24), which covers the cutting-off wheel over a covering area. The cutting-off wheel is rotatably fixedly mounted on the output shaft with the aid of the flange and surrounded by the safety guard (24), which is pivotable around a pivot axis. The safety guard (24), the supporting housing part (36) and the transmission mechanism (19) have maximum distances from the output axis (40) over an outcut angle (), which are less than or equal to half the flange diameter of the flange.

Claims

1. A handheld, hand-guided cutting-off machine comprising: a supporting housing part; a cutting-off wheel having a wheel diameter; an output shaft rotatably supported around an output axis on the housing part with the aid of a bearing element; a drive motor and a transmission mechanism connecting the drive motor to the output shaft, the transmission mechanism being situated on the housing part; a flange having a flange diameter, the cutting-off wheel being rotatably fixedly situatable on the output shaft with the aid of the flange; and a safety guard having a covering area at least partially covering the cutting-off wheel, and a machining area exposing the cutting-off wheel, the safety guard being pivotably supported around a pivot axis on the housing part; the flange diameter of the flange corresponding to a minimum flange diameter, and the safety guard having a first maximum distance from the output axis over a first angle range, the supporting housing part having a second maximum distance from the output axis over a second angle range, and the transmission mechanism has a third maximum distance from the output axis over a third angle range, wherein the first, second and third maximum distances are less than or equal to half the minimum flange diameter.

2. The cutting-off machine as recited in claim 1 wherein the safety guard is adjustable between a front and a rear pivot position, an outcut angle formed as an intersection between the first, second and third angle ranges, being different than zero for at least one pivot position of the safety guard.

3. The cutting-off machine as recited in claim 2 wherein the outcut angle is different than zero for all pivot positions of the safety guard between the front and the rear pivot positions.

4. The cutting-off machine as recited in claim 1 wherein the pivot axis of the safety guard is displaced with respect to the output axis of the output shaft by a distance into the covering area of the safety guard.

5. The cutting-off machine as recited in claim 4 wherein a size of the first angle range is dependent on a pivot position of the safety guard.

6. The cutting-off machine as recited in claim 1 wherein the transmission mechanism includes an output disk situated on the output shaft, and a transmission element transmitting a movement of the drive motor to the output disk, the output disk having a fourth maximum distance and the transmission element having a fifth maximum distance from the output axis over the third angle range, wherein the fourth and fifth maximum distances are less than or equal to half the minimum flange diameter.

7. The cutting-off machine as recited in claim 6 wherein the transmission mechanism includes a cover covering the output disk and the transmission element, the cover having a sixth maximum distance from the output axis over the third angle range, the sixth maximum distance being less than or equal to half the minimum flange diameter.

8. The cutting-off machine as recited in claim 7 wherein the drive motor is a combustion motor, and the cutting-off wheel is designed as a diamond cutting-off wheel or as an abrasive cutting-off wheel.

9. The cutting-off machine as recited in claim 1 wherein the drive motor is an electric motor, and the cutting-off wheel is designed as a diamond cutting-off wheel or as a bound, reinforced cutting-off wheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are described below on the basis of the drawing. The latter is not necessarily intended to represent the exemplary embodiments true to scale but rather the drawing is presented in a schematic and/or slightly distorted form where useful for the purpose of explanation. It should be taken into account that a variety of modifications and changes relating to the form and detail of a specific embodiment may be undertaken without deviating from the general idea of the present invention. The general idea of the present invention is not limited to the exact form or the detail of the preferred specific embodiment illustrated and described below, nor is it limited to an object which would be limited in comparison to the object claimed in the claims. In given measurement ranges, values within the specified limits are also to be disclosed as limiting values and be able to be arbitrarily used and claimed. For the sake of simplicity, the same reference numerals are used below for identical or similar parts or for parts having identical or similar functions.

(2) FIGS. 1A, 1B show a handheld, hand-guided cutting-off machine according to the present invention, including a cutting-off wheel;

(3) FIGS. 2A, 2B show a safety guard and a belt drive of the cutting-off machine illustrated in FIGS. 1A, 1B, including a cover (FIG. 2A) and without a cover (FIG. 2B);

(4) FIGS. 3A, 3B show the safety guard of the cutting-off machine in a front pivot position (FIG. 3A) and a rear pivot position (FIG. 3B);

(5) FIGS. 4A, 4B show the supporting housing part (FIG. 4A) and the transmission mechanism (FIG. 4B) of the cutting-off machine; and

(6) FIGS. 5A, 5B show the cutting-off machine in the front pivot position of the safety guard (FIG. 5A) and the rear pivot position of the safety guard (FIG. 5B).

DETAILED DESCRIPTION

(7) FIGS. 1A, 1B show a handheld, hand-guided power tool 10 according to the present invention, which is designed in the form of a cutting-off machine. Cutting-off machine 10 includes a machining tool designed as a cutting-off wheel 11, which is driven by a drive unit 12 in a rotation direction 13 around a rotation axis 14. All drive components for cutting-off wheel 11 are combined as drive unit 12. In cutting-off machine 10 illustrated in FIG. 1B, a cover 15 was removed, so that at least some drive components of drive unit 12 are visible. Cover 15 may have a single-part or multi-part design and is fastened to cutting-off machine 10 by screws.

(8) Drive unit 12 includes a drive motor 17 situated in a motor housing 16, a transmission mechanism situated in a supporting arm 18 and designed as a belt drive 19, and an output shaft 20, on which cutting-off wheel 11 is mounted. Additional transmission components are connectable as needed between drive motor 17 and belt drive 19. A centrifugal clutch may be situated between drive motor 17 and belt drive 19, which ensures that cutting-off wheel 11 does not rotate at low rotational speeds, such as when idling or when starting cutting-off machine 10. The centrifugal clutch includes a clutch bell, against which the centrifugal weights are pressed outwardly during operation, due to the centrifugal force. Drive motor 17 drives a drive shaft 21 around a drive axis 22. The clutch bell of the centrifugal clutch is rotatably fixedly connected to a drive disk 23, which is rotatably supported on drive shaft 21.

(9) Combustion motors or electric motors are used as drive motors 17 for cutting-off machine 10. All drive motors for motor-operated electric power tools are combined under the term electric motor; the electric power tools may be cable-bound with a direct connection to the grid or wireless without a direct connection to the grid. Cutting-off machines which include a combustion motor may be used with different types of cutting-off wheels 11diamond cutting-off wheels and abrasive cutting-off wheelsthe cutting-off wheels including cutting-off bodies made of bound abrasive materials and/or grinding tools having diamond and CBN abrasive materials. Cutting-off machines which include an electric motor may be used with different types of cutting-off wheels 11: diamond cutting-off wheels and bound, reinforced cutting-off wheels of type 41 or 42.

(10) Cutting-off wheel 11 is surrounded by a safety guard 24, which is used to protect the operator against flying dust particles and also reduces the risk of injury by the operator reaching into rotating cutting-off wheel 11 during the operation of cutting-off machine 10. Safety guard 24 is fastened in a hub area of cutting-off wheel 11 and is made up of a covering area 25, which covers cutting-off wheel 11 over a covering angle of approximately 200, and a machining area 26, which exposes cutting-off wheel 11 over a machining angle of 160 for machining a workpiece. Safety guard 24 is designed to be pivotable and may be pivoted around a pivot axis 27 (FIGS. 2A, 2B) into a desired pivot position. To set the pivot position, a hand grip element 28 is fastened to safety guard 24, which may be used to apply the necessary forces to pivot safety guard 24 around pivot axis 27.

(11) A first handle 31, which has an operating unit 32 and is designed as a top handle, is provided for operating cutting-off machine 10. A handle which is situated above motor housing 16 is referred to as a top handle. Alternatively, the first handle may be designed as a rear handle, which is situated on the side of motor housing 16 facing away from cutting-off wheel 11. In addition to first handle 31, a second handle 33, which is situated between cutting-off wheel 11 and first handle 31, is provided for guiding cutting-off machine 10. In the exemplary embodiment shown in FIGS. 1A, 1B, second handle 33 is designed as a separate gripping tube, or it may be alternatively designed as a single piece with motor housing 16 or another housing part.

(12) FIGS. 2A, 2B show an enlarged representation of safety guard 24 and belt drive 19 of cutting-off machine 10 from FIGS. 1A, 1B. Belt drive 19 is situated in a supporting arm housing 35, which includes a stationary, supporting housing part 36 and cover 15. FIG. 2A shows belt drive 19, including mounted cover 15, and FIG. 2B shows belt drive 19 without cover 15.

(13) The drive of cutting-off wheel 11 takes place via drive motor 17, belt drive 19 and output shaft 20. Drive motor 17 may be designed as a combustion motor or as an electric motor. Drive motor 17 drives drive shaft 21 and drive disk 23 around drive axis 22. A transmission element 38 designed as a drive belt is guided via drive disk 23 and an output disk 39 supported on output shaft 20. Output shaft 20 is rotatable around an output axis 40, which coincides with rotation axis 14 of cutting-off wheel 11. Drive disk 23, drive belt 38 and output disk 39 form belt drive 19. Alternatively, transmission mechanism 19 may be designed, for example, in the form of a chain drive, in which the transmission element between drive disk 23 and output disk 39 is designed as a chain. Cutting-off wheel 11 is situated on output shaft 20 with the aid of a flange 41 and is rotatably fixedly connected to output shaft 20. Flange 41 and cutting-off wheel 11 are mounted on output shaft 20, and cutting-off wheel 11 is situated between two flange halves of flange 41.

(14) A workpiece is machined with the aid of cutting-off machine 10 in the area of cutting-off wheel 11 situated in machining area 26 of safety guard 24. Safety guard 24 includes a fastening flange 42 in the hub area of cutting-off wheel 11, which, in the exemplary embodiment, is designed as a single piece with a side wall 43 of safety guard 24; alternatively, the fastening flange may also be designed as a separate part and connected to safety guard 24. Fastening flange 42 is mounted on a matching counter-contour 44 of the stationary housing part 36 and is designed to be adjustable with respect to counter-contour 44 of housing part 36.

(15) For gas-powered cutting-off machines, the European standard EN ISO 19432:2012, the U.S. standard ANSI B175.4-2013 and corresponding standards in other countries define a minimum flange diameter d.sub.min for flange 41, depending on the type of cutting-off wheel 11 (diamond cutting-off wheel or abrasive cutting-off wheel) and on wheel diameter D of cutting-off wheel 11 (D250 mm, 250 mm<D300 mm, 300 mm<D350 mm and 350 mm<D). For diamond cutting-off wheels, minimum flange diameter d.sub.min is: d.sub.min37.5 mm for D250 mm, d.sub.min=45 mm for 250 mm<D300 mm, d.sub.min=52.5 mm for 300 mm<D350 mm and d.sub.min=60 mm for 350 mm<D. For abrasive cutting-off wheels, minimum flange diameter d.sub.min is: d.sub.min63.5 mm for D250 mm, d.sub.min=75 mm for 250 mm<D300 mm, d.sub.min=87.5 mm for 300 mm<D350 mm and d.sub.min=100 mm for 350 mm<D.

(16) Maximum cutting depth t.sub.max achievable by cutting-off wheel 11 in a workpiece is then achieved if flange diameter d.sub.f of flange 41 corresponds to minimum flange diameter d.sub.min and no components of cutting-off machine 10 additionally limit the cutting depth. Maximum cutting depth t.sub.max is defined by half the difference between wheel diameter D of cutting-off wheel 11 and minimum flange diameter d.sub.min, of flange 41: t.sub.max=*(Dd.sub.mim). In gas-powered cutting-off machines 10 and a diamond cutting-off wheel, maximum cutting depth t.sub.max is: t.sub.max=106.25 mm for D=250 mm, t.sub.max=127.5 mm for D=300 mm, t.sub.max=148.75 mm for D=350 mm and t.sub.max=170 mm for D=400 mm. In gas-powered cutting-off machines and an abrasive cutting-off wheel, maximum cutting depth t.sub.max is: t.sub.max=93.25 mm for D=250 mm, t.sub.max=112.5 mm for D=300 mm, t.sub.max=131.25 mm for D=350 mm and t.sub.max=150 mm for D=400 mm.

(17) FIGS. 3A, 3B show flange 41 and safety guard 24 in a front pivot position (FIG. 3A) and a rear pivot position (FIG. 3B). Safety guard 24 is designed to be pivotable around pivot axis 27 between the front pivot position and the rear pivot position; in the exemplary embodiment, the pivot range of safety guard 24 is limited to an angle range of approximately 60. As in the exemplary embodiment, safety guard 24 may be situated in any arbitrary pivot position between the front and rear pivot positions; alternatively, discrete pivot positions may be provided for safety guard 24 between the front and rear pivot positions.

(18) Pivot axis 27 of safety guard 24 is different than output axis 40 of output shaft 20. Pivot axis 27 is displaced by a distance 4 with respect to output axis 40 into covering area 25 of safety guard 24. The full angle of cutting-off wheel 11 of 360 is divided by safety guard 24 into a covering angle and a machining angle. Covering area 25 of safety guard 24 determines the covering angle, and machining area 26 of safety guard 24 determines the machining angle. In the exemplary embodiment, the covering angle is approximately 200, and the machining angle is approximately 160.

(19) Safety guard 24 has a first outer contour 45. The angle range, in which first outer contour 45 of safety guard 24 has distances from output axis 40 which are less than or equal to half of minimum flange diameter d.sub.min, is defined as first angle range .sub.1. The maximum distance which first outer contour 45 has in first angle range .sub.1 is defined as first maximum distance b.sub.1. First maximum distance b.sub.1 corresponds to half of minimum flange diameter d.sub.min. The position and size of first angle range .sub.1 change during the pivoting of safety guard 24 around pivot axis 27. FIG. 3A shows first angle range .sub.1 in the front pivot position of safety guard 24, and FIG. 3B shows first angle range .sub.1 in the rear pivot position of safety guard 24.

(20) FIGS. 4A, 4B show supporting housing part 36 (FIG. 4A) and transmission mechanism 19 (FIG. 4B) in the area of output shaft 20. To be able to achieve maximum cutting depth t.sub.max with the aid of cutting-off wheel 11, not only safety guard 24 but also supporting housing part 36 and transmission mechanism 19 must be designed in such a way that their outer contours do not project over flange 41.

(21) Supporting housing part 36 has a second outer contour 46. The angle range, in which second outer contour 46 of supporting housing part 36 has distances from output axis 40 which are less than or equal to half of minimum flange diameter d.sub.min, is defined as second angle range .sub.2. The maximum distance which second outer contour 46 has in second angle range .sub.2 is defined as second maximum distance b.sub.2. Second maximum distance b.sub.2 corresponds to half of minimum flange diameter d.sub.min.

(22) Transmission mechanism 19 includes output disk 39, which is situated on output shaft 20, transmission element 38, which transmits a movement of drive motor 17 to output disk 39, and cover 15, which covers output disk 39 and transmission element 38. Output disk 39 and transmission element 38 are rotating components, which must be covered with the aid of cover 15 to meet safety requirements. The outer contour of transmission mechanism 19 is therefore determined by cover 15. Transmission mechanism 19 has a third outer contour 47. The angle range, in which third outer contour 47 of transmission mechanism 19 has distances from output axis 40 which are less than or equal to half of minimum flange diameter d.sub.min, is defined as third angle range .sub.3. The maximum distance which third outer contour 47 has in third angle range .sub.3 is defined as third maximum distance b.sub.3. Third maximum distance b.sub.3 corresponds to half of minimum flange diameter d.sub.min.

(23) If transmission mechanism 19 does not include any rotating components, cover 15 may be eliminated or be provided with a different design. The condition that the maximum distance of transmission mechanism 19 from output axis 40 is less than or equal to half the minimum flange diameter in third angle range .sub.3 must generally be met for each subcomponent of transmission mechanism 19. These include output disk 39, which is situated on output shaft 20, and transmission element 38, which is situated on output disk 39. Output disk 39 has a fourth maximum distance b.sub.4, transmission element 38 has a fifth maximum distance b.sub.5, and cover 15 has a sixth maximum distance b.sub.6. In the exemplary embodiment, sixth maximum distance b.sub.6 of cover 15 corresponds to third maximum distance b.sub.3 of transmission mechanism 19, since third outer contour 47 of transmission mechanism 19 is determined by cover 15.

(24) FIGS. 5A, 5B show cutting-off machine 10 according to the present invention, including safety guard 24, supporting housing part 36 and transmission mechanism 19 in the front pivot position of safety guard 24 (FIG. 5A) and in the rear pivot position of safety guard 24 (FIG. 5B).

(25) Safety guard 24 does not project over flange 41 in first angle range .sub.1, supporting housing part 36 does not project over flange 41 in second angle range .sub.2, and transmission mechanism 19 does not project over flange 41 in third angle range .sub.3. The intersection between first angle range .sub.1, second angle range .sub.2 and third angle range .sub.3 is defined as outcut angle . In outcut angle , safety guard 24, supporting housing part 36 and transmission mechanism 19 have distances from output axis 40 which are less than or equal to half of minimum flange diameter d.sub.min. When the operating angle of cutting-off machine 10 according to the present invention is within outcut angle , maximum cutting depth t.sub.max is achievable, which is defined as half the difference between wheel diameter D of cutting-off wheel 11 and minimum flange diameter d.sub.min.

(26) Since safety guard 24 is pivotable around pivot axis 27, the position of first angle range .sub.1 changes relative to second angle range .sub.2 of supporting housing part 36 and third angle range .sub.3 of transmission mechanism 19. FIG. 5A shows outcut angle in the front pivot position of safety guard 24, and FIG. 5B shows outcut angle in the rear pivot position of safety guard 24. In the exemplary embodiment, outcut angle is approximately 62 in the front pivot position and approximately 55 in the rear pivot position. Outcut angle is different than zero in all pivot positions of safety guard 24 between the front and rear pivot positions. Since outcut angle is different than zero for all pivot positions of safety guard 24, maximum cutting depth t.sub.max is achievable in each pivot position of safety guard 24. Cutting-off machine 10 must only be oriented by the operator in such a way that the operating angle is within outcut angle .