Mobile machine tool with a screw gear having a stop

Abstract

The invention relates to a mobile machine tool (10), in particular a pressing, crimping and / or cutting machine tool, containing a drive (24), a screw gear (28) and a linear actuator (30), wherein a rotational movement generated by the drive (24) can be converted via the screw gear (28) into a linear movement of the linear actuator (30) along a longitudinal axis (L) of the screw gear (28), wherein the screw gear (28) has an inner screw part (38) having an external screw thread (40) and an outer screw part (42) having an internal screw thread (44), wherein the outer and the inner screw parts (38, 42) interact via an intermediate part (46) arranged between the two screw parts (38, 42), wherein the screw gear (28) has at least one stop (48, 50) by means of which a movement range (B) of the intermediate part (46) along the longitudinal axis (L) is limited at least on one side. The mobile machine tool (10) can be produced cost-effectively and is particularly powerful.

Description

[0001] Mobile machine tool with a threaded spindle drive with a stop

[0002] Description

[0003] The invention is based on a mobile machine tool, in particular a pressing, crimping and / or cutting machine tool, comprising a drive, a threaded spindle drive and a linear actuator, wherein a rotary movement generated by the drive can be converted via the threaded spindle drive into a linear movement of the linear actuator along a longitudinal axis of the threaded spindle drive.

[0004] Such machine tools are used, for example, for pressing, cutting or crimping, for example in ventilation, electrical or plumbing installation work in buildings.

[0005] The machine tool should be able to generate the highest possible pressing force at the tool head.

[0006] To ensure long battery operation on a battery-powered machine tool, it should be as energy-efficient as possible. Accordingly, the lead screw drive should have a high load capacity while simultaneously minimizing friction.

[0007] Furthermore, a high speed of the linear movement is desirable in order to achieve the highest possible productivity of the machine tool.

[0008] In order to be able to carry out work in confined spaces, the machine tool should be as small as possible.

[0009] In order to ensure economical operation, production costs should be kept as low as possible.

[0010] The object of the present invention is therefore to offer a mobile machine tool of the type mentioned above which is particularly powerful and yet can be produced cost-effectively.

[0011] The object is achieved by a mobile machine tool, comprising a drive, a threaded spindle drive and a linear actuator, wherein a rotary movement generated by the drive can be converted via the threaded spindle drive into a linear movement of the linear actuator along a longitudinal axis of the threaded spindle drive, wherein the threaded spindle drive has an inner threaded spindle part with an external thread and an outer threaded spindle part with an internal thread, wherein the outer and the inner threaded spindle part interact via an intermediate part arranged between the two threaded spindle parts, wherein the threaded spindle drive has at least one stop by which a range of movement of the intermediate part along the longitudinal axis is limited at least on one side.

[0012] In principle, the threaded spindle drive can offer high load capacities. Friction between the inner and outer threaded spindle sections can be reduced to a very low level by the intermediate part. The intermediate part can have individual elements through which forces and / or torques can be transmitted between the inner and outer threaded sections. For this purpose, the individual elements can be movably accommodated in the intermediate part. The individual elements can protrude into the internal and / or external thread. The individual elements can be, for example, bearing balls and / or bearing rollers.

[0013] Thus, the outer threaded part can be moved relative to the inner threaded part along the longitudinal axis with minimal friction, so that the linear actuator can be actuated by at least one of the two threaded parts. The individual elements can first be installed in the intermediate part, and then the lead screw drive can be cost-effectively assembled from the inner and outer lead screw parts and the intermediate part, thus achieving low manufacturing costs.

[0014] Asymmetrical slippage of the individual elements under load can cause the intermediate part to shift relative to the inner and / or outer threaded spindle part. Under certain circumstances, the intermediate part could move out of the remaining threaded spindle drive. To prevent this, the intermediate part's range of motion is limited by the stop.

[0015] The stop thus makes it possible to use such a threaded spindle drive permanently in a mobile machine tool of the type described above.

[0016] Preferably, the internal and external threads have the same pitch relative to the longitudinal axis so that the individual elements can run simultaneously in both the internal and external threads.

[0017] The range of motion can be limited, in particular, on two sides. Two stops can be provided for this purpose, so that the intermediate part is securely positioned within the remaining threaded spindle part on both sides.

[0018] The stop can be designed tangentially to the longitudinal axis. For this purpose, the stop can, for example, have a section that engages with a thread of the external thread. The stop can, in particular, be designed to strike frontally with a counter-section of the intermediate part that is complementary to the section. This can prevent the intermediate part from becoming stuck to the stop, for example due to unintentional pressure welding. Such jamming could occur, particularly with materials susceptible to this, for example, if the intermediate part were to strike the stop parallel to the longitudinal axis with pressing forces corresponding to the pitch of the external thread and the generated torque. This can reduce maintenance costs and extend the service life.

[0019] The machine tool can be designed as a pressing, crimping and / or cutting machine tool.

[0020] The lead screw drive can convert a rotary movement of the drive into a linear movement of the linear actuator.

[0021] The linear actuator may have a tool head.

[0022] In order to design the machine tool as a press tool, the linear actuator, in particular the tool head, can have at least one press jaw.

[0023] To configure the machine tool as a cutting machine tool, the linear actuator can have at least one cutting jaw. In one class of embodiments, the intermediate part can have at least one bearing roller. Preferably, the intermediate part can have a plurality of bearing rollers. The bearing rollers can be aligned parallel to the longitudinal axis. The bearing rollers can have circumferential grooves.

[0024] Alternatively or additionally, it is conceivable for the intermediate part to have at least one bearing ball. Bearing balls are particularly inexpensive to obtain. Furthermore, they can be accommodated particularly easily in a, for example, cylindrical, support of the intermediate part. The bearing balls can be manufactured with a very high degree of precision. In particular, the intermediate part can have a large number of bearing balls. The bearing balls can be evenly distributed over the intermediate part. They can be arranged along a helix. In particular, they can be arranged complementarily to the internal and / or external thread. This allows the bearing balls to run particularly reliably and with low friction in the internal and / or external thread.

[0025] The at least one stop can be formed on the outer threaded spindle part. It can thus limit the range of motion of the intermediate part relative to the outer threaded spindle part.

[0026] The at least one stop can be formed on the inner threaded spindle part. Then, the range of motion of the intermediate part relative to the inner threaded spindle part can be limited.

[0027] The at least one stop can be configured, in particular shaped, to cooperate with at least one end face of the intermediate part.

[0028] In particular, it is conceivable for the threaded spindle drive to have at least two stops. The at least two stops can be located in front of or on opposite ends of the intermediate part.

[0029] It is particularly conceivable that one of the stops is formed on the inner part of the threaded spindle and another of the stops is formed on the outer part, so that a particularly long stroke can be achieved.

[0030] With at least two stops, it can be ensured that the intermediate part is always located between the inner and outer threaded spindle parts. In particular, it can be ensured that the intermediate part cannot slip off either the inner or outer thread. This limits slippage-related movements of the intermediate part on both sides.

[0031] The intermediate part can be shorter than the internal thread, so that the intermediate part can be completely absorbed by the external thread. In other words, the longest extension of the intermediate part in a direction parallel to the longitudinal axis can be shorter than the longest extension of the internal thread in a direction parallel to the longitudinal axis.

[0032] The intermediate part can also be shorter than the external thread, so that the entire intermediate part can be located on a circumferential surface of the inner threaded spindle part. In other words, the longest extension of the intermediate part in a direction parallel to the longitudinal axis can be shorter than the longest extension of the external thread in a direction parallel to the longitudinal axis.

[0033] The machine tool is mobile. In particular, it can be designed as a handheld power tool. It can be portable. To this end, it can have a weight of less than 10 kg, preferably less than 5 kg, for example less than 3 kg. It can furthermore have at least one handle. Alternatively or additionally, it is also conceivable for it to be designed for use on a construction robot. In particular, it can be arranged and / or mounted on a multi-axis arm, for example, with at least six degrees of freedom.

[0034] It can be designed to generate pressing and / or cutting forces of at least 10 kN, for example, at least 30 kN. It can thus be designed for particularly high performance characteristics.

[0035] The mobile machine tool can be portable. It can have a total weight of less than 25 kg, in particular less than 10 kg. It can, in particular, be a hand-held power tool.

[0036] Further features and advantages of the invention will become apparent from the following detailed description of exemplary embodiments of the invention, based on the figures of the drawing, which illustrate details essential to the invention, and from the claims. The features shown therein are not necessarily to scale and are presented in such a way that the special features of the invention can be clearly seen. The various features can be implemented individually or in combinations in variants of the invention.

[0037] The schematic drawing shows embodiments of the invention and explains them in more detail in the following description.

[0038] They show:

[0039] Fig. 1 a mobile machine tool in the form of a press tool in a schematic side view,

[0040] Fig. 2 shows a section of the mobile machine tool with a threaded spindle drive in a partially sectioned longitudinal view,

[0041] Fig. 3 shows a further section with another threaded spindle drive in a partially sectioned longitudinal view and

[0042] Fig. 4a to 4c schematic longitudinal sectional views of the threaded spindle drive.

[0043] In the following description of the figures, the same reference numerals are used for identical or functionally corresponding elements to facilitate understanding of the invention.

[0044] Fig. 1 shows a mobile machine tool 10 in the form of a pressing tool, in particular a hand-held pipe press. Instead of being configured as a pipe press, the machine tool 10 can also be configured as any other mobile cutting or forming tool. Thus, it is also possible, in particular, for the machine tool 10 according to the invention to be configured as a dispensing device for chemical substances, such as adhesive or dowel compound. Such dispensing devices can also be referred to as dispensers.

[0045] As can be seen in Fig. 1, the power tool 10 comprises a housing 12, a tool 14, and a power supply 16. The power supply 16 is positioned at one end of the housing 12. In the present exemplary embodiment, the power supply 16 is configured as a rechargeable battery (also called a battery or accumulator), preferably a lithium-based rechargeable battery. Alternatively or additionally, it is also conceivable for the power supply to have a wired power connection or an inductive power transmission interface.

[0046] The tool 14 is formed at an opposite end of the housing 12. The tool 14 is designed in the form of a forming tool 20. In the present embodiment, the forming tool 20 is designed as a so-called pressing head and has two pressing jaws 21 movable in opposite directions. The forming tool 20 is used, for example, for processing and, in particular, for forming lines, for example, pipes. The lines are not shown in the figures.

[0047] An activation switch 22 is positioned on the underside of the housing 12. The activation switch 22 can be used to start and stop the machine tool 10.

[0048] The housing 12 is shown in Fig. 1 only with its outline, so that elements of the machine tool 10 located in the housing 12 can also be seen in Fig. 1.

[0049] In particular, a controller 23 is located in the housing 12, which is configured to control a drive 24. The drive 24 can, for example, comprise a brushless electric motor. It is configured to drive the tool 14 along a longitudinal axis L via a threaded spindle drive 28. In the present embodiment, in which the tool 14 is the forming tool 20, the drive 24 is thus configured to move the pressing jaws 21.

[0050] Fig. 2 shows a partially sectioned view of the machine tool 10 (see Fig. 1) with the threaded spindle drive 28.

[0051] The drive 24 (see Fig. 1) is connected to the threaded spindle drive 28 via a drive shaft 26. A torque generated by the drive 24 can thus be transmitted to the threaded spindle drive 28.

[0052] The threaded spindle drive 28 can convert a rotary movement of the drive 24 into a linear movement of a push rod 32 of the linear actuator 30 along the longitudinal axis L. The threaded spindle drive 28 acts on a piston 33 of the linear actuator 30. The piston 33 is filled with a fluid 34, in particular a silicone oil. If the piston 33 is thus moved along the longitudinal axis L in the direction of the push rod 32, the fluid 34 presses on the push rod 32 and thus drives it linearly. The fluid 34 can provide damping. By appropriately dimensioning the piston 33 and selecting a fluid 34 with a suitable compression modulus, the effective overall stiffness of the parts of the machine tool 10 subject to compressive loads can be adjusted. This makes it possible to reduce or avoid the risk of breakage in overload situations.

[0053] The piston 33 is sealed by a seal 35, for example in the form of a sealing ring. A projection 36, for example in the form of a sliding block, is located on an outer side of the piston 33. The projection 36 engages in a guide groove 37 of the housing 12. Thus, the piston 33 is fixed to the housing 12 in a rotationally fixed manner but is longitudinally displaceable along the longitudinal axis L.

[0054] The linear actuator 30 acts on the forming tool 20 with its pressing jaws 21. Depending on the direction of movement of the linear actuator 30, the pressing jaws 21 can be opened or closed.

[0055] The threaded spindle drive 28 has an inner threaded spindle part 38 with an external thread 40. It also has an outer threaded spindle part 42 with an internal thread 44. The outer and inner threaded spindle parts 38, 42 interact via an intermediate part 46 arranged between the two threaded spindle parts 38, 42.

[0056] The outer threaded spindle part 42 is connected to the housing 12 in a rotationally fixed manner.

[0057] A first stop 48 is formed on the inner threaded spindle part 38 along the circumference of the external thread 40. The stop 48 is formed tangentially to the longitudinal axis L. A second stop 50 is formed on the outer threaded spindle part 42 along the inner circumference of the internal thread 44. The stop 48 is also formed tangentially to the longitudinal axis L.

[0058] The first stop 48 thus moves with the inner threaded spindle part 38. The second stop 50, on the other hand, is connected in a rotationally fixed manner to the outer threaded spindle part 42 and thus to the housing 12 (see Fig. 1). Thus, during the rotational movement, the range of motion of the intermediate part 46 along a longitudinal axis L of the threaded spindle drive 28 is limited on two sides, in particular on a first end face by the first stop 48 and on an opposite, second end face by the second stop 50.

[0059] The intermediate part 46 is shorter than the external thread 40 and also shorter than the internal thread 44, so that it can move between both threads 40, 44.

[0060] The intermediate part 46 has a plurality of bearing rollers 51, of which, for the sake of simplicity, only one bearing roller 51 is provided with a reference numeral. The bearing rollers 51 are rotatably arranged along the circumference of the intermediate part 46, in particular in a bearing shell 53. They run, on the one hand, in inner grooves 54 of the internal thread 44 and, on the other hand, in outer grooves 56 of the external thread 40. They thus support the inner threaded spindle part 38 on the outer threaded spindle part 42. Due to the plurality of bearing rollers 51, the bearing is supported on a plurality of bearing points corresponding to the bearing rollers 51, resulting in a high load capacity of the bearing. The bearing on the bearing rollers 51 nevertheless results in low bearing friction, even under high compressive loads along the longitudinal axis L.

[0061] Fig. 3 shows a section of the machine tool 10 (see Fig. 1) of an alternative embodiment with an alternative threaded spindle drive 28 in a partially sectioned view.

[0062] This alternative embodiment corresponds, unless otherwise explained below, to the embodiment according to Fig. 2.

[0063] However, it differs from the latter in the design of the intermediate part 46. In particular, the intermediate part 46 of this embodiment has, instead of the bearing rollers

[0064] 51 (see Fig. 2) has a plurality of bearing balls 52. Again, for the sake of simplicity, only one of the bearing balls 52 is provided with a reference symbol in Fig. 3. The bearing balls

[0065] 52 are arranged in a helical manner along the circumference of the intermediate part 46, in particular in the bearing shell 53. They run on the one hand in the inner grooves 54 of the internal thread 44 and on the other hand in the outer grooves 56 of the external thread 40. They are thus mounted analogously to the

[0066] Bearing rollers 51, the inner threaded spindle part 38 on the outer threaded spindle part 42. Due to the large number of bearing balls 52, the bearing is carried out on a large number of bearing points corresponding to the bearing balls 52, so that in this embodiment too, a high load capacity of the bearing is achieved with low bearing friction even under high compressive loads along the longitudinal axis L.

[0067] The intermediate part 46 of this embodiment can be manufactured particularly cost-effectively. The bearing shell 53 only requires essentially circular recesses, which can be created, for example, by drilling or punching. The bearing balls 52 can be easily inserted into these recesses and rotatably held by them.

[0068] The bearing balls 52 can have a diameter that is larger than the width of the grooves of the bearing rollers 51 according to Fig. 2. Accordingly, the inner grooves 54 of the internal thread 44 and the outer grooves 56 of the external thread 40 can be adapted to the size of the bearing balls 52. In particular, they can be wider than in the embodiment according to Fig. 2.

[0069] The functional principle of the threaded spindle drive 28 is explained in more detail using the schematic representations in Fig. 4a to Fig. 4c.

[0070] Fig. 4a shows an initial position of the threaded spindle drive 28, in which the forming tool 20 (see Fig. 1) is maximally open. In this position, the inner threaded spindle part 38 is in a maximally retracted position. In this position, the intermediate part 46 sits between the first and second stops 48 and 50 and contacts each of them from one side.

[0071] If the threaded spindle drive 28 is extended a short distance by means of the rotary movement of the drive 24 (see Fig. 2), for example, to the position shown in Fig. 4b, the inner threaded spindle part 38 extends, with the first stop 48 moving away from the second stop 50. This increases the range of motion B within which the intermediate part 46 can move.

[0072] As the inner threaded spindle part 38 extends, the forming tool 20 closes until it is completely closed, i.e., until the pressing jaws 21 (see Fig. 1) press against each other with maximum force or maximum pressure. The corresponding end position of the threaded spindle drive 28 is shown in Fig. 4c. It can be seen that the threaded spindle parts 38, 42 are preferably dimensioned such that the intermediate part 46 is still completely located between the two threaded spindle parts 38, 42, even in the end position.

[0073] List of reference symbols

[0074] 10 Machine tool

[0075] 12 housings

[0076] 14 tools

[0077] 16 Energy supply

[0078] 20 forming tools

[0079] 21 Press jaw

[0080] 22 activation switches

[0081] 23 Control

[0082] 24 drive

[0083] 26 Drive shaft

[0084] 28 Threaded spindle drive

[0085] 30 linear actuator

[0086] 32 push rod

[0087] 33 pistons

[0088] 34 Fluid

[0089] 35 Seal

[0090] 36 lead

[0091] 37 Guide groove

[0092] 38 inner threaded spindle part

[0093] 40 external threads

[0094] 42 outer threaded spindle part

[0095] 44 internal thread

[0096] 46 Intermediate part

[0097] 48 first attack

[0098] 50 second attack

[0099] 51 bearing roller

[0100] 52 bearing ball

[0101] 53 bearing shell

[0102] 54 inner groove

[0103] 56 outer groove

[0104] B Range of motion

[0105] L Longitudinal axis

Claims

Patent claims 1 . Mobile machine tool (10), in particular a pressing, crimping and / or cutting machine tool, comprising a drive (24), a threaded spindle drive (28) and a linear actuator (30), wherein a rotary movement generated by the drive (24) can be converted via the threaded spindle drive (28) into a linear movement of the linear actuator (30) along a longitudinal axis (L) of the threaded spindle drive (28), wherein the threaded spindle drive (28) has an inner threaded spindle part (38) with an external thread (40) and an outer threaded spindle part (42) with an internal thread (44), wherein the outer and the inner threaded spindle part (38, 42) interact via an intermediate part (46) arranged between the two threaded spindle parts (38, 42), wherein the threaded spindle drive (28) has at least one stop (48, 50) by means of which a movement range (B) of the Intermediate part (46) is limited at least on one side along the longitudinal axis (L).

2. Machine tool (10) according to the preceding claim, characterized in that the stop (48, 50) is designed to strike tangentially.

3. Machine tool (10) according to one of the preceding claims, characterized in that the movement range (B) is limited on two sides.

4. Machine tool (10) according to one of the preceding claims, characterized in that the linear actuator (30) has at least one pressing jaw (21).

5. Machine tool (10) according to one of the preceding claims, characterized in that the linear actuator (30) has at least one cutting jaw.

6. Machine tool (10) according to one of the preceding claims, characterized in that the intermediate part (46) has at least one bearing roller (51).

7. Machine tool (10) according to one of the preceding claims, characterized in that the intermediate part (46) has at least one bearing ball (52).

8. Machine tool (10) according to one of the preceding claims, characterized in that the at least one stop (48, 50) is formed on the outer threaded spindle part (42).

9. Machine tool (10) according to one of the preceding claims, characterized in that the at least one stop (48, 50) is formed on the inner threaded spindle part (38).

10. Machine tool (10) according to one of the preceding claims, characterized in that the threaded spindle drive (28) has two stops (48, 50) which are located in front of or on opposite end faces of the intermediate part (46), one of the stops (48, 50) being formed on the inner threaded spindle part (38) and another of the stops (48, 50) being formed on the outer threaded spindle part (42).

11. Machine tool (10) according to one of the preceding claims, characterized in that the intermediate part (46) is shorter than the internal thread (44).

12. Machine tool (10) according to one of the preceding claims, characterized in that the intermediate part (46) is shorter than the external thread (40).

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