WO2011047959A1

WO2011047959A1 - Machine tool and method for cooling a machine tool

Info

Publication number: WO2011047959A1
Application number: PCT/EP2010/064882
Authority: WO
Inventors: Willy Braun
Original assignee: Robert Bosch Gmbh
Priority date: 2009-10-19
Filing date: 2010-10-06
Publication date: 2011-04-28
Also published as: EP2490862A1; CN102596512B; DE102009045799A1; CN102596512A

Abstract

The invention relates to a machine tool having a housing (12) and a tool holder (14) movably arranged on the housing (12) for receiving an inserted tool (16). The machine tool according to the invention furthermore has a drive device (22) in the housing (12) comprising a drive unit (18, 48, 50) and a transmission unit (20) for driving the inserted tool (16), which generates waste heat during operation. According to the invention, the transmission unit (16) comprises at least one cooling body (88).

Description

Description title

Machine tool and method for cooling a machine tool prior art

The invention relates to a machine tool, in particular a hand tool according to the preamble of claim 1.

There are already known machine tools with a housing, a tool holder movably arranged on the housing for receiving an insertion tool and a drive device accommodated in the housing for driving the tool. In an operation of the drive device, which has a drive unit and a gear unit, a waste heat is generated. In particular, in known drills and / or impact hammers a significant amount of waste and / or waste heat is generated during operation. Particularly high amounts of heat and thus high temperatures arise in a front region of these hand tool machines, where a plurality of heat sources is arranged. These are, for example, a heat of compression from an air cushion of a striking mechanism of the hammer and / or percussion hammer, occurring impact losses from the impact processes between elements of the percussion mechanism, possible friction losses inside the percussion mechanism by relative movements between elements of the percussion mechanism and / or friction losses of other moving components of the impact mechanism. and / or percussion hammer. In order to limit a thermal load on the internal components, the heat loss must be derived to a sufficient extent from a housing interior to the outside. A heat transfer takes place here mainly via heat pipe. In the example of the known drills and / or impact hammers has a large part of the Schlagwerk generated heat to be dissipated via two bearing points of the hammer mechanism belonging to the hammer tube. Due to the design of these bearings but only small contact surfaces or contact surfaces, so that the heat transfer surface and thus the transmittable heat are rather low. Consequently, the thermal load of the percussion components lying in the housing in the known designs of drills and / or impact hammers is particularly high.

The heat loss to the exterior surface of the percussion unit is largely dissipated to the environment by convection. An air mass flow required for convection is usually generated by a fan connected to the drive unit. In order to guide the air mass flow to a front region of the rotary hammer and / or percussion hammer and to protect the operator from harmful contact temperatures, a striking mechanism housing surrounding the impact mechanism is often surrounded by an additional plastic housing. But since the hottest part of this percussion gear housing is often at the end of the cold chain, there is only insufficient heat transfer to the outside at this point.

For this it is known, for example from DE 10 2004 058 696 AI, to effectively bring air into the front regions via the so-called Venturi nozzle effect. The utilization of this effect requires a relatively complex construction of the hammer drill.

Disclosure of the invention

Advantages of the invention

The machine tool according to the invention, in particular

Hand tool, with the features of the main claim has the advantage that the transmission unit comprises at least one heat sink. By the heat sink can be advantageously achieved that occurring in the transmission unit waste heat can be delivered particularly effectively to a surrounding air mass flow. The measures listed in the dependent claims, advantageous refinements and improvements of the main claim features.

An effective and space-saving design can be achieved in that the gear unit comprises an at least rotatable shaft which is at least partially surrounded by the heat sink. It may be of particular advantage when the rotatable shaft is mounted in the heat sink.

In a particularly effective embodiment, the heat sink encloses the at least rotatable shaft substantially coaxially.

If the heat sink is at least substantially non-rotatably connected, preferably non-rotatably connected to the at least rotatable shaft, then a heat transfer can proceed even more effectively. In a particularly preferred embodiment, the heat sink is designed as a centrifugal disk.

In order to improve the efficiency of the transmission element designed as a heat sink with respect to a removal of the waste heat, the transmission element designed as a heat sink has at least one subregion provided with cooling fins.

In a further advantageous development, the heat sink has at least one heat-absorbing connection region. In this case, a heat-accepting connection region is understood in particular to be a region on the heat sink, at which it is in contact, preferably in direct contact, with a heat-emitting body, so that the lowest possible heat transfer resistance is produced. A direct contact can be made, for example, by positive and / or positive and / or cohesive connection. In a particularly simple embodiment, the contact is formed as a press fit. Alternatively or additionally, in a further embodiment in the connection region, a heat-conducting substance such as a thermal paste can be advantageously used.

In a preferred embodiment of the machine tool at least parts of the gear unit are arranged in a gear housing, which is accommodated in the housing. Preferably, the gear housing is made of a metallic material, in particular steel.

In a particularly advantageous embodiment, the gear housing has at least on one surface at least one gas-permeable surface structure in a surface direction. In this case, a surface direction is understood to mean, in particular, an extension direction of the surface. In this case, a gas-permeable surface structure is to be understood as meaning, in particular, a structure which opposes, to a gas flowing in the structure, the lowest possible, preferably almost vanishing, resistance. The inflowing gas may preferably be air. In a particularly simple embodiment, the surface structure may be formed as at least one overflow groove.

For a particularly effective removal of the waste heat in the housing at least one air inlet opening is provided, via which a cooling air flow for the removal of at least a portion of the waste heat can flow into the housing. Furthermore, at least one air outlet opening is provided in a transition region between the tool holder and the housing, via which at least a fraction of the cooling air flow can exit.

In order to prevent any damage by dust penetrating, designed as a heat sink gear element has at least a dust-tight sealing point. This dust-tight sealing point prevents direct contact of the gear unit with the cooling air flow at least as far as possible, preferably almost completely. In a preferred embodiment, the at least rotatable shaft is an at least rotatable working spindle, in particular a hammer tube. In a particularly preferred embodiment, the machine tool according to the invention is a hand tool, in particular a drill and / or chisel hammer.

In a further aspect, the invention relates to a method for cooling a machine tool, in particular a hand tool, which has a drive device accommodated in a housing, having a drive unit and a gear unit. In an operation of the

Drive device is generated while a waste heat, wherein at least one provided in the housing air inlet opening a cooling air flow to a removal of at least a portion of the waste heat flows into the housing. It is proposed that at least part of the cooling air flow flows over a heat sink arranged on a rotatable shaft of the transmission unit.

Description of the drawings

An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. Show it:

Figure 1 is a schematic side view of a drilling and / or

Schlaghammer, Figure 2 is a partial section of a front portion of the hammer drill

Figure 1 with a bearing carrier according to the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS FIG. 1 shows a schematic view of a drill and / or chisel hammer 10 as an example of a machine tool with a housing 12, a tool holder 14 movably mounted on the housing 12 for receiving an insertion tool 16 and a drive unit 18 and accommodated in the housing 12 a transmission unit 20 having drive device 22 for driving the insert tool 16. The tool holder 14 is preferably rotatably arranged on an end face 24 of the housing 12. On one of the end face 24 of the housing 12 opposite side of the housing 12, a handle device 26 is further provided in the example of Figure 1 further. In the present example, the handle device 26 comprises a main device switch 28 for commissioning the drill and / or chisel hammer 10. Furthermore, an auxiliary handle device 30 is arranged, in particular adjustably, on the housing 12 of the drill and / or chisel hammer 10. The housing 12 of the rotary and / or chisel hammer 10 furthermore has at least one, preferably two or more ventilation openings 32. Depending on an air flow direction 34, 36, the ventilation opening 32 acts either as an air inlet opening 38 or as an air outlet opening 40. At least, however, an air inlet opening 38 is provided on the housing 12.

In an intermediate region 42 between the housing 12 and the tool holder 14, in particular between the housing 12 and a jacket sleeve 44 of the tool holder 14, an additional air outlet opening 46 is provided.

The drive unit 18 comprises in the present example a motor 48, in particular an electric motor 50 and a motor shaft, not shown here. The motor 48, 50 is operatively connected to the gear unit 20 via the motor shaft.

The gear unit 20 of the drilling and / or chiselling hammer 10 described here has, in a known form, a rotary drive gear and / or a hammer mechanism with a percussion drive gear. In known drilling and / or chipping hammers 10, the hammer mechanism is often designed as a so-called air cushion or air spring impact mechanism. As already described at the beginning, airbag impact devices in many ways contribute to a waste heat of the drive device 22 of the drill and / or chisel hammer 10. FIG. 2 shows a front section of the drill and / or chisel hammer 10 in a partial section.

The tool holder 14 has, in addition to the jacket sleeve 44, a tool holder 52, which is preferably made of a metallic material, in particular a steel, and a locking device 56 comprising at least one locking element 54. In the tool holder 52, a spigot 58 of the insert tool 16 is received and locked via the locking device 56.

The gear unit 20 of the rotary and / or chisel hammer 10 has a work spindle 60, preferably a hammer tube 61 as an example of a rotatable shaft 59. The tool holder 52 is here exemplarily inserted into an open end 62 of the work spindle 60, 61 and preferably rotatably and axially immovably connected to the work spindle 60, 61. In the example according to FIG. 2, the tool holder 52 is connected to the work spindle 60, 61 by means of the locking body 64 engaging in the tool holder 52 and passing through the work spindle 60, 61.

The work spindle 60, 61 is received via a sliding bearing 66 in a transmission housing 68 and rotatably supported relative thereto. The gear housing 68 is delimited outwardly from the housing 12, in particular a hammer tube hood 70 and at least partially enclosed. In this case, the gear housing 68 is made in particular of a metallic material, preferably of a steel. The hammer tube hood 70, like the housing 12, is preferably made of a plastic. Between the work spindle 60, 61 and the gear housing 68, a felt ring 72 and a radial shaft seal 74 are further arranged, via which the gear housing 68 is sealed against dust entering.

In a transition region between the tool holder 52 and the work spindle 60, 61 a striker 76 is further provided. The firing pin 76 has one or more earrings 78, via which a Interior 80 of the work spindle 60, 61 is sealed against penetrating dust.

In so far corresponds to the structure of the drill and or chisel hammer 10 shown in Figure 1 or 2 a well-known series concept for drilling and / or

Hammers. A large part of the heat generated in the interior of the percussion mechanism - in particular in the work spindle and in the tool holder - has to be dissipated outwards to the transmission housing 68 by means of heat conduction via the narrow play bearing sliding bearing 66. The work spindle 60, 61 has virtually no possibility of waste heat through an efficient, convective

Dissipate heat dissipation, since the work spindle 60, 61 is practically thermally isolated from the surrounding components. The same applies in a similar context, of course, for the thermally coupled tool holder 14th

In the according to Figure 2 according to the invention executed drill and / or chisel hammer 10, the gear housing 68 has at least one Überströmnut 82. In this case, the overflow groove 82 extends along a surface direction 71 along a surface 69 of the gear housing 68. A surface direction is understood to mean in particular a direction which runs parallel to the surface 69 and, in particular, follows the surface profile in a spatial direction in a local coordinate system of the surface 69. The Überströmnut 82 is located in a support region of the gear housing 68 relative to the hammer tube cover 70 and the housing 12 of the hammer drill 10. The Überströmnut 82 has the task to flow an air mass flow 84 in the direction of the tool holder 14. In addition to the Überstömnuten shown here 82 are also known other gas-permeable surface structures 83 known in the art, which can be used according to the invention to produce a convective cooling of the impact mechanism. For example, you can

Surface depressions and / or lattice structures are used according to the invention. It can also be alternatively or additionally provided that a corresponding gas-permeable surface structure 83 'is provided on an inner surface of the housing 12 in the support region. In a connection region 86 between the work spindle 60, 61 and the tool holder 52, a heat sink 88 is arranged radially on the outside of the work spindle 60, 61, preferably non-rotatably connected to the work spindle 60, 61. In this case, a heat sink 88 is understood in particular to be an element which has a large heat conduction and / or heat transfer surface and / or convection surface and / or a low heat transfer resistance. The heat sink 88 is designed in the embodiment of Figure 2 as a mainly sleeve-like component. In this case, the heat sink 88 preferably extends positively and / or non-positively via the connection region 86. In the present example, the heat sink 88 is therefore in particular non-rotatably connected to the work spindle 60, 61. In addition to the positive and / or non-positive connection of the heat sink 88 to the work spindle 60, 61, the person skilled in the art is familiar with further connection techniques which can be used alternatively or additionally according to the invention. Thus, for example, a cohesive connection can be used by soldering or welding as an alternative or complementary connection technology. Also, in the connection region 86, a heat-conducting material, in particular a thermal compound, the heat transfer from the work spindle 60, 61 may be introduced to the heat sink 88 favoring.

In a preferred embodiment, as shown in FIG. 2, the heat sink 88 further has a sealing labyrinth 90 formed in common with the gearbox housing 68. The sealing labyrinth 90 serves for improved dust sealing of the gear housing 68 against penetrating, dust-containing air, for example, from the air mass flow 84.

The heat sink 88 preferably has one or more preferably a plurality of cooling fins 92 projecting into the air mass flow 84. The air mass flow 84 thus flows over the overflow grooves 82 and the cooling ribs 92. Thereafter, the air mass flow 84 exits via the additional air outlet opening 46 provided in the transition region 42 into the environment. A waste heat generated in particular in the front region of the hammer drill 10 can thus be discharged efficiently via the cooling ribs 92 of the heat sink 88 to the air mass flow 84. The heat sink 88 may also have additional features over which additional functions can be displayed. Thus, for example, a Abdichtlabyrinth 94 may be provided, via which an inner space 96 of the tool holder 14 is protected from penetrating dust. Furthermore, the heat sink 88 can also be used as a carrier for sealing elements 98.

In the embodiment according to FIG. 2, the cooling body 88 is arranged coaxially around the working spindle 60, 61 and is designed in particular as a centrifugal disk 100. This has the advantage that by a rotary movement of the work spindle 60, 61, the sealing effect and the cooling effect of the heat sink 88, 100 are still reinforced.

Depending on a specific embodiment of the machine tool, the person skilled in the art will, on the basis of the features and functions of the heat sink 88 described here, adapt the latter to the requirements, without changing the advantages and effects essential to the invention.

Claims

claims

1. A machine tool having a housing (12), a on the housing (12) movably arranged tool holder (14) for receiving an insert tool (16) and housed in the housing (12), a drive unit (18, 48, 50) and a transmission unit (20) having drive device (22) for driving the

Insertion tool (16), which generates waste heat in one operation, characterized in that the transmission unit (16) comprises at least one heat sink (88).

2. Machine tool according to claim 1, characterized in that the

Transmission unit (20) comprises an at least rotatable shaft (59) which is at least partially surrounded by the heat sink.

3. Machine tool according to claim 2, characterized in that the

Heatsink (88) encloses the at least rotatable shaft (59) substantially coaxially.

4. Machine tool according to claim 2 or 3, characterized in that the cooling body (88) at least substantially non-rotatably, preferably non-rotatably connected to the at least rotatable shaft (59).

5. Machine tool according to at least one of claims 2 to 4, characterized

in that the heat sink (88) is designed as a centrifugal separator (100).

6. Machine tool according to at least one of the preceding claims,

characterized in that the heat sink (88) at least one with

Having cooling ribs (92) provided partial area.

7. Machine tool according to at least one of the preceding claims,

characterized in that the heat sink (88) has at least one heat receiving connection region (86).

8. Machine tool according to at least one of the preceding claims, characterized in that at least parts of the gear unit (20) in a transmission housing (68) are arranged, which is accommodated in the housing (12).

9. Machine tool according to claim 8, characterized in that the

Gear housing (68) at least on one surface (69) at least one in a surface direction (71) gas-permeable surface structure (83), preferably at least one overflow groove (82) in a surface direction (71).

10. Machine tool according to at least one of the preceding claims,

characterized in that in the housing (12) at least one

Air inlet opening (38) is provided, via which a cooling air flow to a removal of at least a portion of the waste heat in the housing (12) can flow, and that in a transition region (42) between the tool holder (14) and the housing (12) at least one Air outlet opening (46) is provided for the exit of at least a fraction of the cooling air flow.

11. Machine tool according to at least one of the preceding claims,

characterized in that the heat sink (88) has at least one dust-tight sealing point (90, 94) via which a direct contact of the gear unit (20) with the cooling air flow as far as possible, preferably almost completely prevented.

12. Machine tool according to at least one of claims 2 to 11, characterized

characterized in that the at least rotatable shaft (59) is an at least rotatable working spindle (60), in particular a hammer tube (61).

13. Machine tool according to at least one of the preceding claims,

characterized in that the machine tool a

Hand tool, in particular a drill and / or chisel hammer (10).

14. Method for cooling a machine tool, in particular a

Hand tool having a in a housing (12) recorded, a drive unit (18) and a transmission unit (20) having drive device (22) which generates a waste heat in one operation, wherein at least one in the housing (12) provided air inlet opening ( 38) to a cooling air flow a removal of at least a portion of the waste heat flows into the housing (12), characterized in that at least a portion of the cooling air flow via a at least rotatable shaft (59) of the transmission unit (20) arranged cooling body (88) flows.