EP-4741107-A1 - GUIDE TUBE FOR A POWER TOOL, POWER TOOL

Abstract

Guide tube (1) for a power tool (2), in particular for a drill or chisel hammer, comprising a tubular base body (3) made of steel and a reinforcing structure (4) which surrounds the base body (3) on its outer circumference at least partially and is made of a material which has a lower density than steel. Power tool (2), in particular a rotary hammer or chisel hammer, with such a guide tube (1).

Inventors

• Knyrim, Maximilian
• GEIGER, STEFFEN
• Mucha, Steffen
• LIEBERT, BERNHARD
• Barabanov, Andreas

Assignees

• Hilti Aktiengesellschaft

Dates

Publication Date

20260513

Application Date

20241108

Claims (10)

1. Guide tube (1) for a power tool (2), in particular for a drill or chisel hammer, comprising a tubular base body (3) made of steel and a reinforcing structure (4) which surrounds the base body (3) on its outer circumference at least partially and is made of a material which has a lower density than steel.
2. Guide tube (1) according to claim 1, characterized in that the reinforcement structure (4) is connected to the base body (3) by force, form and/or material connection.
3. Guide tube (1) according to claim 1 or 2, characterized in that the reinforcement structure (4) extends over at least 20%, preferably over at least 30%, and further preferably over at least 50% of the length of the base body (3).
4. Guide tube (1) according to one of the preceding claims, characterized in that the reinforcement structure (4) is tubular, ribbed and/or grid-like.
5. Guide tube (1) according to one of the preceding claims, characterized in that the reinforcement structure (4) has at least one rib (5) extending substantially in the circumferential direction, which is preferably formed circumferentially and/or has a slope.
6. Guide tube (1) according to one of the preceding claims, characterized in that the reinforcement structure (4) has several ribs (6) extending essentially in the axial direction, which are preferably arranged at equal angular intervals from each other or are arranged in groups parallel to each other.
7. Guide tube (1) according to claim 6, characterized in that the axially extending ribs (6) are each chamfered at at least one end.
8. Guide tube (1) according to one of the preceding claims, characterized in that the base body (3) has a wall thickness (s) of 0.5 mm to 5 mm and/or the reinforcement structure (4) has a thickness (d) of 1 mm to 5 mm.
9. Guide tube (1) according to one of the preceding claims, characterized in that the base body (3) has at least one opening (7) on the outer surface which a) is exposed by a defect (8) or opening (9) in the reinforcement structure (4) or b) opens into a channel (10) formed in the reinforcement structure (4).
10. Power tool (2), in particular a drill or chisel hammer, with a guide tube (1) according to one of the preceding claims, wherein preferably at least one piston (11, 12) of an impact mechanism (13) is axially displaceable in the guide tube (1).

Description

The invention relates to a guide tube for a power tool, in particular for a rotary hammer or chisel hammer. Furthermore, the invention relates to a power tool, in particular a rotary hammer or chisel hammer, with a guide tube according to the invention. State of the art Rotary hammers and/or chisel hammers are well-known. They feature a striking mechanism with a piston for direct or indirect impact on a tool, such as a chisel. In a pneumatic striking mechanism, the piston is coupled via an air spring to an exciter piston, which moves the piston back and forth in the direction of impact. The piston and exciter piston are guided longitudinally in the direction of impact by a guide tube. The guide tube is subjected to high stresses during operation of the power tool. These stresses can lead to deformation of the guide tube. For example, the stresses can cause the tube to bend longitudinally and/or deform its cross-section, so that a formerly circular cross-section becomes oval or ellipse. To prevent such deformations, the guide tube is usually made of a high-strength material, such as steel. To further increase its strength, especially its rigidity, the wall thickness of the guide tube can be increased. However, this also increases the weight of the guide tube, which is undesirable. The present invention is therefore concerned with the objective of providing a guide tube that has sufficient dimensional stability while having the lowest possible weight. To solve the problem, a guide tube with the features of claim 1 is proposed. Advantageous embodiments of the invention are described in the dependent claims. Furthermore, a power tool with a guide tube according to the invention is described. Disclosure of the invention A guide tube for a power tool, in particular for a drill or chisel hammer, is proposed, comprising a tubular base body made of steel and a reinforcing structure that surrounds the base body at least partially on its outer circumference and is made of a material that has a lower density than steel. The externally arranged reinforcement structure allows for a reduction in the wall thickness of the tubular steel body, resulting in a lighter weight. While the reinforcement structure does add weight, it is made of a material with a lower density than steel, meaning the weight increase is less than the weight savings achieved through the reduced wall thickness of the base body. At the same time, the reinforcement structure ensures the required dimensional stability of the guide tube. Preferably, the reinforcement structure is made of aluminum or plastic, as these materials have a lower density than steel and simultaneously enable a stable bond with the tubular steel base. The guide tube can therefore be designed as a composite body. If the material is plastic, it is proposed that it be a fiber-reinforced plastic to further increase the load-bearing capacity of the resulting reinforcement structure. If the steel base body is combined with a plastic reinforcement structure, meaning the guide tube is designed as a steel-plastic hybrid body, the base body performs the guiding and sealing functions. Furthermore, it fulfills the thermal requirements placed on the guide tube. The mechanical stability requirements are met by the plastic reinforcement structure. The reinforcement structure is preferably connected to the base body by force-fit, form-fit, and/or material-fit connection. This force-fit, form-fit, and/or material-fit connection between the base body and the reinforcement structure ensures a strong bond and thus prevents relative movement of the reinforcement structure with respect to the base body under load. To create a material-fit connection, the tubular base body can be overmolded with the material used to form the reinforcement structure. A form-fit connection can simultaneously be achieved by means of undercut recesses on the outer surface of the base body. These recesses can be subsequently introduced into the base body using a material-removing process, such as laser machining, or can be molded in during the manufacturing of the base body. A force-fit connection between the base body and the reinforcement structure can be achieved via an interference fit. Furthermore, it is proposed that the reinforcement structure extend over at least 20%, preferably at least 30%, and more preferably at least 50% of the length of the base body. The arrangement of the reinforcement structure can be specifically limited to those areas of the base body that are particularly susceptible to deformation under load. This means that the reinforcement structure is preferably arranged substantially centrally in the axial direction, i.e., along the length of the guide tube. It also means that the reinforcement structure is spaced apart from both ends of the base body. Preferably, the reinforcement structure is tubular, ribbed, and/or grid-like. In the tubular version, the reinforcement structure can be The base body