Machine tool

Abstract

The invention relates to a machine tool (10) comprising a drive (20), for example a pneumatic drive (20), and a housing shell (12), and the drive (20) is mounted on the housing shell (12) by at least one sliding bearing (32). The invention is characterized in that the sliding bearing (32) comprises a friction-reducing element (36). As a result, additional holders, for example additional handles (14), can be correctly and easily arranged on the machine tool (10).

Description

[0001] machine tool

[0002] Description

[0003] The invention relates to a machine tool comprising a drive and a housing shell, wherein the drive is mounted on the housing shell via at least one plain bearing. The drive can be, for example, an electropneumatic drive. The machine tool can be a hand-held machine tool.

[0004] Often, an additional bracket, such as an auxiliary handle, needs to be attached to such a machine tool. The bracket may have a mounting clamp that allows it to be attached to the machine tool.

[0005] For example, in hand-held machine tools, it is recommended for ergonomic and functional reasons to attach the bracket to the housing shell near the plain bearing. However, the user should ensure that the mounting clamp is tightened with a torque within a narrowly defined torque range. If the torque is too high, the plain bearing may be over-tensioned and jammed, for example. If the torque is too low, the bracket will not be properly seated on the housing shell.

[0006] During normal use of the machine tool with such a mount, malfunctions or failures frequently occur. This can also lead to health damage for the machine tool user, for example, if the user is exposed to excessive vibration.

[0007] The object of the present invention is therefore to provide a machine tool of the type mentioned above that allows for the proper assembly of an additional mounting bracket in a particularly simple manner. It is particularly desirable for the machine tool to be cost-effective to manufacture. This object is achieved by a machine tool comprising a drive, for example an electropneumatic drive, and a housing shell. The drive is mounted on the housing shell via at least one plain bearing, the plain bearing having a friction-reducing means.

[0008] This makes it possible, in a surprisingly simple and particularly cost-effective way, to significantly expand the permissible torque range for properly fastening a mounting clamp, a bracket, or the like, to the housing shell. For example, the friction-reducing agent enables the sliding movement of the body mounted in the plain bearing, such as a machine tool axis, even if the mounting clamp exerts increased pressure on the plain bearing.

[0009] Investigations have shown that the permissible torque range of a machine tool can be extended to such an extent that a user can tighten the mounting clamp without additional measuring tools or the like and still remain within the permissible torque range. Furthermore, the user can usually detect insufficient torque themselves, since in this case the mounting clamp is obviously too loose for the user, for example, slightly movable, on the housing shell.

[0010] This provides a particularly simple and convenient way to equip the machine tool with an additional mounting bracket, such as an auxiliary handle. This eliminates the need for additional measuring tools or special training for the user.

[0011] It is also still possible to use a plain bearing to support the drive. The advantages associated with a plain bearing, such as good dust and dirt resistance and low manufacturing costs, are retained. In particular, there is no need to switch to a different bearing type, such as a ball bearing or a roller bearing. Considerable additional costs associated with such a change can be avoided.

[0012] Friction-reducing agents are generally available at very low cost. This also allows the machine tool to be manufactured cost-effectively despite the improved comfort it provides.

[0013] It has also been shown, and will be explained in more detail below, that at least one of the basic functions of the plain bearing, in particular the lowest possible transmission of vibrations from the drive to the housing shell and thus further to any mounted holder, in particular an additional handle, is further improved.

[0014] The plain bearing may have sliding surfaces. The friction-reducing agent may be applied to the sliding surfaces.

[0015] Accordingly, a particularly advantageous machine tool can have a holder arranged on the housing shell via a fastening section that can be removed, in particular without tools. The holder can, for example, be an additional side handle. While maintaining or improving the basic function of the plain bearing, the holder provides an additional option for safely guiding the machine tool. This can be necessary, especially for particularly powerful machine tools, such as hammer drills or chiseling machines.

[0016] The mounting section can have a mounting clamp, allowing it to be flexibly adapted to the different dimensions of different machine tool designs. The mounting clamp also allows the bracket to be attached to or removed from the machine tool without causing any damage.

[0017] It is advantageous if the friction-reducing agent remains in the plain bearing for an extended period of time and / or under high and / or long-term continuous loads. The friction-reducing agent should also be as robust as possible with regard to dust and dirt, which are always to be expected on construction sites, for example.

[0018] It is therefore also advantageous if the friction reducing agent comprises a solid lubricant and in particular is such.

[0019] Alternatively or additionally, it is conceivable for the friction-reducing agent to comprise a liquid lubricant. A liquid lubricant can be understood as a lubricant that is liquid at room temperature, for example, 18-25°C, in particular 20°C, or at a typical operating temperature, for example, an operating temperature in the range of 30°C to 130°C, for example, 80°C.

[0020] In one class of embodiments, a lubricant reservoir may be provided.

[0021] This means that the plain bearing can be supplied with friction reducing agents over a long period of time, for example over 5, 10 or 20 years.

[0022] The friction-reducing agent can comprise a plurality of microparticles, particularly lubricant-filled microparticles. The microparticles can serve as a lubricant reservoir.

[0023] A particularly advantageous feature is that the microparticles can already be located directly at their desired sites of action. The microparticles can thus release lubricants directly on site. Another particularly advantageous feature is that under high loads, such as those that can occur with fastening clamps tightened with high torques, a particularly large number of microparticles can open and release their lubricant contents. This allows friction-reducing agents to be provided to the plain bearing in a particularly tailored manner.

[0024] In machine tools with an impact function, the drives, such as electro-pneumatic drives, generate impacts along their longitudinal axes and thus particularly strong vibrations. Effective vibration reduction is particularly important for these machine tools. Therefore, if such machine tools are designed with an impact function as described here, health risks for users who, for example, mount and use an additional handle on the machine tool can be reduced or even completely eliminated.

[0025] The machine tool can be mounted on a construction robot. It can be configured to perform construction work on a ceiling, a wall, and / or a floor. It can have a manipulator. An end effector can be formed at a free end of the manipulator. The machine tool can be mounted and / or capable of being mounted on the end effector.

[0026] The manipulator can be designed as a robot arm. The manipulator can also have a lifting device. The lifting device can increase the total volume accessible to the manipulator. The manipulator can have at least three degrees of freedom. In particular, it can have at least six degrees of freedom.

[0027] The construction robot can also have a mobile platform. The mobile platform can comprise a wheeled chassis and / or a tracked chassis. The mobile platform can have at least two degrees of freedom. The construction robot can have a total of at least eight, for example ten, degrees of freedom.

[0028] With conventional machine tools, vibrations from the machine tool can be transmitted to the end effector of the construction robot. The end effector therefore also begins to vibrate, so that construction work can only be carried out by the construction robot with low precision. The end effector, the manipulator, and / or the mobile platform of the construction robot are also subjected to particularly high mechanical stress due to the vibrations. It is therefore particularly advantageous if the construction robot has a machine tool of the type described here, so that a holder can be mounted on the machine tool, which, if necessary, enables additional mounting of the machine tool, so that no or only a very minimal amount of vibration is transmitted to the construction robot.

[0029] Alternatively or additionally, it is conceivable for the machine tool to be designed as a handheld power tool. For example, an auxiliary handle can be mounted on such a machine tool, through which vibrations are transmitted to a minimal extent during operation. Health risks caused by excessive vibration exposure, for example to a user's hand, can be avoided or at least significantly reduced.

[0030] In general, the machine tool can be designed to perform construction work on a building construction site and / or a civil engineering site. It can be specifically designed for processing rock, such as concrete. Machine tools with an impact function and particularly high single impact energies are used especially for processing rock. To ensure safe operation of the machine tool despite these high single impact energies, an additional handle is recommended, so that the aforementioned advantages can be particularly effective with such a machine tool.

[0031] 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.

[0032] The schematic drawing shows embodiments of the invention and explains them in more detail in the following description.

[0033] They show:

[0034] Fig. 1 is a side view of a machine tool with an additional handle and Fig. 2 is a longitudinal sectional view of a plain bearing of the machine tool.

[0035] 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.

[0036] Fig. 1 shows a machine tool 10. The machine tool 10 is designed as a handheld power tool. The machine tool 10 is designed, in particular, as a hammer drill. It thus has an impact function.

[0037] Fig. 1 shows a side view of a portion of the machine tool 10. It shows a housing shell 12 to which an auxiliary handle 14 is mounted via a fastening section 16. The fastening section 16 has a fastening clamp 18. The fastening clamp 18 wraps around a front area of ​​the housing shell 12.

[0038] The machine tool 10 has a drive 20. The drive 20 is located within the housing shell 12 and is therefore only shown schematically in Fig. 1.

[0039] The drive 20 has an electropneumatic motor unit 22. The motor unit 22 drives a tool axis 24. In particular, the tool axis 24 can be driven in a rotational, percussive, and / or rotary-percussive manner. The tool axis 24 can comprise a steel material. In particular, it can be formed from a steel material. The tool axis 24 opens into a tool holder 26. A tool can be mounted in the tool holder 26. For example, the tool can be a chisel tool or a hammer drill.

[0040] The mounting clamp 18 has a clamping screw 28. The clamping screw 28 can be used to adjust the length of the mounting clamp 18 and thus its diameter. Thus, depending on the torque with which the clamping screw 28 is tightened, the pressure on the housing shell 12 can be increased or decreased. This also allows the tightness of the fit of the mounting clamp 18 to the housing shell 12 to be adjusted.

[0041] Fig. 2 now shows a section of the machine tool 10 in area II according to Fig. 1. To simplify the illustration, the additional handle 14 with its fastening clamp 18 and the housing shell 12 (see Fig. 1 in each case) are not shown.

[0042] Fig. 2 shows in particular a perspective, partially sectioned view of the illustrated area II. The tool axis 24 (see also Fig. 1) is also not shown. This results in a view of the interior of the housing shell 12 in the illustrated area II. In particular, a plain bearing 32 can be seen. The plain bearing 32 is thus located between the housing shell 12 and the tool axis 24. The plain bearing 32 thus supports the tool axis 24 on the housing shell 12. The bearing can be direct or indirect. With direct bearing, the tool axis 24 can rest on the plain bearing 32. In an alternative embodiment with indirect bearing, the tool axis 24 can be surrounded by a drive housing, at least radially all the way around. The drive housing can then rest on the plain bearing 32, so that the tool axis 24 is mounted indirectly on the plain bearing 32 via the drive housing.

[0043] The sliding bearing 32 has a plurality of sliding surfaces 34. To simplify the illustration, only one of the sliding surfaces 34 is provided with a reference symbol. The sliding surfaces 34 are distributed, for example, at equal distances from one another over the entire inner surface of the sliding bearing 32. The sliding surfaces 34 can be formed from a polymer. Friction-reducing agent 36 is located on the outer sides of the sliding surfaces 34 and / or inside the sliding surfaces 34.

[0044] An example of a suitable friction reducing agent 36 may include the following components:

[0045] The base material may be a polyoxymethylene (e.g., material known as "Hostaform C9021") containing polyurethane (PU)-based microcapsules, for example, containing 10 to 15 weight percent, for example 12.5 weight percent, of the friction-reducing agent 36. The microcapsules contain a lubricant. The lubricant contained in the microcapsules may be a mixture of substances.

[0046] Their capsule walls can be polyurethane-based, in particular made of polyurethane. In general, the capsule walls can comprise a plastic, in particular a polymer.

[0047] The total amount of lubricant contained in the microcapsules may be at least 50% by weight, for example between 50 and 95% by weight, for example in the range of 75 to 85% by weight, in particular 80% by weight, of the weight of the microcapsules.

[0048] The diameters of the microcapsules can range from 20 to 250 pm. For example, their median diameter can be in the range from 1 to 100 pm, in particular from 20 to 50 pm.

[0049] The friction-reducing agent 36 thus comprises microcapsules 38. Again, for the sake of simplicity, only one of the microcapsules 38 is marked with a reference symbol in Fig. 2. The microcapsules 38 can be formed as microparticles or nanoparticles.

[0050] The friction reducing agent 36 may also comprise a solid lubricant, for example based on MOS2 or PTFE.

[0051] List of reference symbols

[0052] 10 Machine tool

[0053] 12 Housing shell

[0054] 14 Additional handle

[0055] 16 Fastening section

[0056] 18 Mounting clamp

[0057] 20 drive

[0058] 22 Motor unit

[0059] 24 tool axis

[0060] 26 Tool holder

[0061] 28 clamping screw

[0062] 32 plain bearings

[0063] 34 Sliding surface

[0064] 36 Friction reducing agents

[0065] 38 microcapsules

[0066] 11 Area

Claims

Patent claims 1. Machine tool (10), comprising a drive (20), for example an electropneumatic drive (20), and a housing shell (12), wherein the drive (20) is mounted on the housing shell (12) via at least one plain bearing (32), characterized in that the plain bearing (32) has a friction-reducing means (36).

2. Machine tool (10) according to the preceding claim, characterized in that the machine tool (10) has a holder, for example an additional handle (14), arranged on the housing shell (12) via a fastening section (16) in a detachable manner, in particular detachable without tools.

3. Machine tool (10) according to one of the preceding claims, characterized in that the fastening section (16) has a fastening clamp (18).

4. Machine tool (10) according to one of the preceding claims, characterized in that the friction reducing agent (36) comprises a solid lubricant and / or a liquid lubricant.

5. Machine tool (10) according to one of the preceding claims, characterized in that the friction reducing agent (36) comprises a plurality of microparticles, in particular lubricant-filled microparticles.

6. Machine tool (10) according to one of the preceding claims, characterized in that the machine tool (10) has an impact function.

7. Machine tool (10) according to one of the preceding claims, characterized in that the machine tool (10) is designed as a hand-held machine tool.

Images