ABRASIVE CUTTER AND METHOD FOR CUTTING THROUGH A RAIL OF A TRACK

Abstract

An abrasive cutter for cutting a rail of a track includes a drive for driving a cutting disc holder in rotation. A cutting disc is attached to the cutting disc holder with at least one clamping element. The drive is directly coupled to the cutting disc holder and has a maximum transverse extent which is at most equal to a diameter of at least one clamping element. The drive has an electric drive motor with a power density P.sub.Spez≥0.5 kW/kg. The abrasive cutter allows a reliable, efficient, user-friendly and low-maintenance through-cutting of a rail of a track.

Claims

1. An abrasive cutter for cutting through a rail of a track, the abrasive cutter comprising: a base body; a cutting disc holder for mounting a cutting disc; and a drive for driving the cutting disc holder in rotation about a rotational axis, wherein: said drive is directly coupled to the cutting disc holder; said drive includes an electric drive motor; said electric drive motor (15 has a drive axis aligned with the rotational axis; said drive has a maximum transverse extent that is at most equal to a diameter of at least one clamping element for fixing the cutting disc to said cutting disc holder; and said electric drive motor has a power density P.sub.Spez, with P.sub.Spez≤0.5 kW/kg.

2. The abrasive cutter according to claim 1, wherein said electric drive motor has a drive shaft formed in one piece with said cutting disc holder.

3. The abrasive cutter according to claim 1, wherein said electric drive motor has a drive shaft and wherein said drive shaft and said cutting disc holder are formed in two pieces.

4. The abrasive cutter according to claim 1, wherein said drive is arranged on said base body.

5. The abrasive cutter according to claim 1, wherein said drive has a housing, and wherein a first bearing is supported on said housing of said drive and a second bearing is supported on said base body.

6. The abrasive cutter according to claim 1, wherein said drive has a housing, and wherein a first bearing and a second bearing are supported on said housing of said drive.

7. The abrasive cutter according to claim 1, wherein said electric drive motor is a brushless electric motor.

8. The abrasive cutter according to claim 1, wherein for the power density P.sub.Spez applies: P.sub.Spez≥0.8 kW/kg.

9. The abrasive cutter according to claim 1, wherein for the power density P.sub.Spez applies: P.sub.Spez≥1.0 kW/kg.

10. The abrasive cutter according to claim 1, further comprising at least one temperature sensor for determining a temperature of said drive and a temperature of a control unit.

11. The abrasive cutter according to claim 1, further comprising a control unit for controlling said drive in dependence on a determined temperature.

12. The abrasive cutter according to claim 1, further comprising a control unit configured to perform at least one of the following method steps: reducing an emittable power of said electric drive motor when a determined temperature exceeds a first temperature limit value; or shutting down said electric drive motor when a determined temperature exceeds a second temperature limit value.

13. The abrasive cutter according to claim 1, further comprising a cooling system for cooling at least one of said electric drive motor or a control unit.

14. A method for cutting through a rail of a track, the method comprising: providing an abrasive cutter according to claim 1; and cutting through the rail with a cutting disc that is driven in rotation by the abrasive cutter.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0055] FIG. 1 shows a perspective view of an abrasive cutter according to a first exemplary embodiment,

[0056] FIG. 2 shows a top view of the abrasive cutter from FIG. 1,

[0057] FIG. 3 shows a side view of the abrasive cutter from FIG. 1,

[0058] FIG. 4 shows a rear view of the abrasive cutter from FIG. 1,

[0059] FIG. 5 shows a section through the abrasive cutter along Line V-V in FIG. 2,

[0060] FIG. 6 shows a section through an abrasive cutter according to a second exemplary embodiment,

[0061] FIG. 7 shows a side view of an abrasive cutter according to a third exemplary embodiment,

[0062] FIG. 8 shows a section through the abrasive cutter along cut line VIII-VIII in FIG. 7, and

[0063] FIG. 9 shows a section through the abrasive cutter along cut line IX-IX in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

[0064] FIGS. 1 to 5 show an abrasive cutter 1 according to a first exemplary embodiment. The abrasive cutter 1 serves for cutting through a rail of a track. For reasons of clarity, the track is not depicted in the figures.

[0065] FIGS. 1 to 4 show the abrasive cutter comprising a base body 2, a drive 4 with the drive axis A.sub.1, and a cutting disc 5. The drive 4 serves to drive the cutting disc 4 about a rotational axis A.sub.2. According to the exemplary embodiment depicted, the rotational axis A.sub.2 and the drive axis A.sub.1 are aligned. The rotational axis A.sub.2 is therefore identical to the drive axis A.sub.1.

[0066] The base body 2 has a pivotable handle 8 for holding and manually guiding the abrasive cutter 1. The base body 2 defines a base body plane G which runs through the base body 2 and perpendicularly to the rotational axis A.sub.2. The drive 4 and the cutting disc 5 are arranged on different sides of the base body plane G. The drive 4 is arranged on a first side G.sub.1 of the base body 2, while the cutting disc 5 is arranged on a second side G.sub.2 of the base body 2. The first side G.sub.1 lies opposite the second side G.sub.2.

[0067] The drive 4 has a housing 9 via which the drive 4 is fixed to the base body 2 in a fixing region 16 by fixing means 17. The fixing means 17 are in particular visible in FIG. 5. In comparison with a maximum width B of the base body 2, the fixing region 16 has a substantially smaller width b. For the width b, b≤0.1.Math.B. Because the fixing region 16 has such a smaller width b, the drive 4 is arranged substantially closer to the base body 2, which counters a shift in the center of gravity of the abrasive cutter 1 in the direction of the first side G.sub.1.

[0068] To control spark emission and protect an operator, a spark protection 7 is arranged on the base body 2 and partially surrounds the cutting disc 5.

[0069] FIG. 5 shows a section through the abrasive cutter 1 along cut line V-V in FIG. 2. In the exemplary embodiment shown, the cutting disc 5 is arranged on a cutting disc holder 3 via a first clamping element 13a and a second clamping element 13b. The clamping elements 13a and 13b each have a same diameter D. The cutting disc 5 is thus arranged between the two clamping elements 13a and 13b on the cutting disc holder 3 and attached thereto.

[0070] The spark protection 7 and the clamping element 13a and 13b define a cutting region 6 which is formed on a region of the cutting disc 5 that is not surrounded by the spark protection 7 or the first clamping element 13a or second clamping element 13b. The cutting region 6 is the region in which the cutting disc 5 comes or may come into contact with the rail (not shown) during the cutting process. The cutting region 6 forms a plane of symmetry S.sub.T.

[0071] The second clamping element 13b has a passage opening via which this can be pushed onto the cutting disc holder 3 and thus come to rest against a stop 20 of the cutting disc holder 3.

[0072] To attach the first clamping element 13a and hence attach the cutting disc 5 between the first and second clamping elements 13a and 13b, the cutting disc holder 3 has an axial bore 19 with internal thread in which a clamping element holder 18, in the form of a screw with an external thread, can be inserted. The first clamping element 13a for this has a passage opening through which the threaded portion of the clamping element holder 18 can be passed. The first clamping element 13a is fixed to an end 21 of the cutting disc holder 3 by the clamping element holder 18 after this has been screwed in.

[0073] The clamping elements 13a and 13b are configured such that they attach the cutting disc 5 by clamping, whereby on rotation of the cutting disc holder 3, the cutting disc 5 rotates via the two clamping elements. In the exemplary embodiment shown, the clamping elements 13a and 13b are each configured, starting from the rotary axis A.sub.2 in the direction of their outer edges 22a and 22b, such that they are deformed towards the cutting disc 5 and sprung. Because of this deformation, a plurality of different cutting discs with different widths can be attached by means of the clamping elements 13a and 13b, since these deform depending on the width of the cutting disc 5 to be mounted, but still have a corresponding clamping effect.

[0074] An electric drive motor 15 with a drive shaft 10 is arranged in the housing 9 of the drive 4. In the exemplary embodiment shown, the electric drive motor 15 is configured as a brushless electric motor. The electric drive motor 15 has a rotor which comprises the drive shaft 10 and permanent magnets arranged thereon. The electric drive motor 15 furthermore comprises a stator having several electromagnets. The permanent magnets and the electromagnets are not illustrated in detail in the figures. The electric drive motor 15 has a power density P.sub.Spez≤0.5 kW/kg. The drive shaft 10 defines the drive axis A.sub.1. The drive 4 is attached to the fixing region 16 of the base body 2 via the fixing means 17 in the form of bolts.

[0075] In the exemplary embodiment shown, the drive 4 has a maximum transverse extent E which is equal to the diameter D of the clamping elements 13a and 13b. The maximum extent E is defined perpendicularly to the drive axis A.sub.1 in the plane of symmetry S.sub.T. Because the maximum transverse extent E of the drive 4 is at most equal to the diameter D of the clamping elements 13a and 13b, it is ensured that the drive 4 does not protrude into the cutting region 6 and hence reduce this. The abrasive cutter 1 serves for use of cutting discs 5 with a maximum nominal diameter D.sub.N. The maximum nominal diameter D.sub.N is in particular established by the spark protection 7. In particular, E≤0.5.Math.D.sub.N.

[0076] In the exemplary embodiment shown, the drive shaft 10 is mounted on the housing 9 of the drive 4 via a first bearing 11, while the cutting disc holder 3 is mounted in the fixing region 16 of the base body 2 via a second bearing 12. The abrasive cutter 1 comprises a control unit 26 for actuating the drive 4.

[0077] In the exemplary embodiment shown, the drive shaft 10 of the drive 4 is configured as a hollow shaft in the engagement region 23, and has a receiving opening for receiving the cutting disc holder 3. The drive shaft 10 is connected by form fit to the cutting disc holder 3 by means of a feather key 14, whereby the drive 4 is directly coupled to the cutting disc holder 3 via the drive shaft 10. On rotation of the drive shaft 10, therefore, the cutting disc holder 3 also rotates. The cutting disc holder 3 defines the rotational axis A.sub.2.

[0078] The function of the abrasive cutter 1 is as follows:

[0079] Firstly, the cutting disc 5 is mounted on the cutting disc holder 3 by the clamping elements 13a and 13b. For this, the second clamping element 13b is pushed onto the cutting disc holder 3 and bears on the stop 20. Then the cutting disc 5 is pushed onto the cutting disc holder 3. Then the first clamping element 13a is fixed to the cutting disc holder 3 by means of the clamping element holder 18, whereby the cutting disc 5 is clamped between the two clamping elements 13a and 13b. In this way, the cutting disc 5 is actively connected to the cutting disc holder 3. The drive shaft 10 is set in rotation by the control unit 26 which serves to control the drive 4. Because the drive shaft 10 is coupled directly to the cutting disc holder 3 by the feather key 14, the rotary motion of the drive shaft 10 is directly transmitted to the cutting disc holder 3. Since the cutting disc 5 is actively connected to the cutting disc holder 3 via the clamping elements 13a and 13b, the rotary motion of the cutting disc holder 3 is transmitted to the cutting disc 5. During the cutting process, the cutting disc 5 is successively worn away, reducing the diameter of the cutting disc 5. Because the maximum transverse extent E of the drive 4 is at most equal to the diameter D of the clamping elements 13a and 13b, the useful cutting region 6 extends up to the clamping elements 13a and 13b.

[0080] The electric drive motor 15 can be driven in rotation in different rotational directions by means of the control unit 26. The rotational direction may be set manually and/or automatically. The rotational direction is set for example by means of at least one control switch, preferably by means of a respective control switch, and/or automatically as a function of a holding position of the abrasive cutter 1, for example by means of a sensor.

[0081] With reference to FIG. 6, a second exemplary embodiment of the abrasive cutter 1 is described. In the second exemplary embodiment, the cutting disc holder 3 is formed in one piece with the drive shaft 10. The cutting disc holder 3 and the drive shaft 10 thus form a common shaft 24. Accordingly, the torque of the drive 4 is transmitted via the common shaft 24 to the first and second clamping elements 13a and 13b and hence to the cutting disc 5. The first bearing 11 and the second bearing 12 are supported on the housing 9. With respect to the further construction and further function, reference is made to the preceding exemplary embodiment.

[0082] A third exemplary embodiment of the invention is described below with reference to FIGS. 7 to 9. The base body 2 is formed extremely compactly. First handles 8 are fixedly arranged on the base body 2. In addition, second handles 8′ are arranged on the base body 2. The second handles 8′ are formed cylindrically and extend spaced apart from and parallel to each other. The second handles 8′ run substantially perpendicularly to the drive axis A.sub.1 on a side of the base body 2 which faces away from the drive 4 relative to the first handles 8. The handles 8′ are connected together and stabilized by means of a spacer 27.

[0083] The electric drive motor 15 is arranged in the housing 9. The housing 9 is configured in two parts. The housing 9 comprises a pot-like first housing component 28 and a lid-like second housing component 29. The first bearing 11 is mounted in the first housing component 28, while the second bearing 12 is mounted in the second housing component 29. The second housing component 29 is attached in the fixing region 16 and releasably connected to the first housing component 28. The drive shaft 10 is connected integrally to the cutting disc holder 3. The drive axis A.sub.1 and the rotational axis A.sub.2 are arranged coaxially to one another.

[0084] The drive motor 15 is configured as a brushless electric motor. The drive motor 15 comprises a stator which is arranged rotationally fixedly relative to the housing 9. The stator 30 comprises electromagnets (not shown in detail) in the usual fashion. The stator 30 surrounds and delimits an interior in which a rotor 31 is arranged. The rotor 31 comprises permanent magnets 31′ and the drive shaft 10 in the usual fashion. The permanent magnets 31′ are attached, for example bonded, to the drive shaft 10. The rotor 31 may be driven in rotation about the drive axis A.sub.1 by means of the stator 30.

[0085] The abrasive cutter 1 comprises a first temperature sensor 32 which is arranged inside the housing 9 on the electric drive motor 15. The first temperature sensor 32 is in signal connection with the control unit 26, and transmits thereto measurement values of a first temperature T.sub.1 of the electric drive motor 15. The abrasive cutter 1 furthermore comprises a second temperature sensor 33. The second temperature sensor 33 is arranged on the control unit 26 and integrated together therewith in the base body 2. The second temperature sensor 33 is in signal connection with the control unit 26, and transmits thereto measurement values of a second temperature T.sub.2 of the control unit 26.

[0086] In the control unit 26, a first temperature limit value T.sub.G1, for example 100° C., and a second temperature limit value T.sub.G2, for example 120° C., are predefined. The control unit 26 repeatedly compares the measurement values of the first temperature T.sub.1 and the second temperature T.sub.2 with the temperature limit values T.sub.G1 and T.sub.G2. If one of the temperatures T.sub.1 and/or T.sub.2 exceeds the first temperature limit value T.sub.G1, the consumable or emittable power P.sub.R of the abrasive cutter 1 is reduced. The abrasive cutter 1 has a nominal power of 2 kW≤P≤3 kW, for example P=2.5 kW. If one of the temperatures T.sub.1 and/or T.sub.2 exceeds the first temperature limit value T.sub.G1, the emittable power P.sub.R is reduced by means of the control unit 26, for example to P.sub.R=0.7.Math.P. The power is reduced for a predefined duration. If one of the temperatures T.sub.1 and/or T.sub.2 exceeds the second temperature limit value T.sub.G2, the abrasive cutter 1 is shut down by means of the control unit 26. The shut-down takes place for predefined duration. In this way, a temperature monitoring is implemented and an overheating of the drive 4 and/or control unit 26 is avoided.

[0087] The abrasive cutter 1 comprises an active cooling system 34 for cooling the drive 4 and/or the control unit 26. The active cooling system 34 produced a movement of a cooling medium L. The cooling medium L in the present exemplary embodiment is air. The cooling system 34 comprises an inflow channel 35, a fan wheel 36 and an outflow channel 37. The fan wheel 36 is attached to the common shaft 24 between the electric drive motor 15 and the second clamping element 13b, and can be driven in rotation by means of the electric drive motor 15. The fan wheel 36 is for example formed in one piece with the second clamping element 13b. The inflow channel 35 is formed L-shaped in cross-section. The inflow channel 35 firstly runs between the base body 2 and the housing 9 in the direction of the drive axis A.sub.1. In the fixing region 16, the inflow channel 35 changes direction and in the fixing region 16 runs between the housing 9 and the second clamping element 13b. The inflow channel 35 runs up to the fan wheel 36. The aspirated air L changes its flow direction at the fan wheel 36 and passes over the fan wheel 36 in the direction of the drive axis A.sub.1. Then the outflow channel 37 begins. The outflow channel 37 runs from the fan wheel 36 between the base body 2 and the spark protection 7. The outflowing air L flows substantially perpendicularly to the drive axis A.sub.1.

[0088] The electric drive motor 15 can be driven in rotation by means of the control unit 26 in a first rotational direction d.sub.1 or in a second opposite rotational direction d.sub.2. To set the respective rotational direction d.sub.1, d.sub.2, the abrasive cutter 1 has a first control switch S.sub.1 and a second control switch S.sub.2. If the first control switch S.sub.1 is actuated, the electric drive motor 15 is driven in rotation in the first rotational direction d.sub.1. If however the second control switch S.sub.2 is actuated, the electric drive motor 15 is driven in rotation in the second rotational direction d.sub.2.

[0089] When cutting through a rail, the abrasive cutter 1 is operated with a power P.sub.B which is higher than the nominal power P. It takes between around 1 minute and 2 minutes to cut through a rail, so during this period the abrasive cutter 1 does not overheat. During rotation of the shaft 24, in particular during through-cutting of a rail, the electric drive motor 15 and the control unit 26 are cooled by means of the cooling system 34. If the abrasive cutter 1 is adequately cooled before cutting through a further rail, the further rail may be cut using the abrasive cutter 1 in the manner described without the abrasive cutter 1 overheating.

[0090] If the abrasive cutter 1 is greatly heated because of repeated cutting processes, then a safe operation of the abrasive cutter 1 is guaranteed by the temperature monitoring. If one of the temperatures T.sub.1 and/or T.sub.2 exceeds the first temperature limit value T.sub.G1, initially the power P.sub.B is reduced to the power P.sub.R and the abrasive cutter 1 is operated with the reduced power P.sub.R. This avoids further heating of the abrasive cutter 1 and subsequent overheating. If however one of the temperatures T.sub.1 and/or T.sub.2 exceeds the second temperature limit value T.sub.G2, the abrasive cutter 1 is shut down temporarily. With respect to the further structure and further function, reference is made to the preceding exemplary embodiments.

[0091] In general:

[0092] The abrasive cutter 1 may be connected to an external energy supply unit by means of an energy supply connection, and/or may comprise its own energy supply unit. An energy supply unit may for example be an accumulator or an accumulator arrangement. The energy supply unit may for example be attached to the base body 2 and/or be integrated in the base body 2. Preferably, the energy supply unit 2 can be recharged and/or exchanged.