Screw system with pneumatic suspension and method for operating the screw system

Abstract

The invention relates to a screw system (100) for the automated screwing in of a screw element, comprising: - a screwdriver (110); - a drive unit (120) for the rotary drive of the screwdriver (110); - a coupling device (130) arranged along a rotational axis (D) between the drive device (120) and the screwing tool (110), comprising a drive shaft (133) and a rotatably connected output shaft (134) arranged along the rotational axis (D) and movable relative to each other in the axial direction. According to the invention, the coupling device (130) has a pneumatic suspension with constant spring force acting in the axial direction between the drive shaft (133) and the output shaft (134), so that the contact force (F) applied to the screwing element by the screwing tool (110) remains constant during a screwing operation. The invention further relates to a method for operating the screw system (100).

Description

[0001] The invention relates to a screw system for the automated screwing in of a screw element according to the preamble of claim 1. The invention further relates to a method for operating the screw system.

[0002] When automatically screwing in a fastener, a rotary motion is applied to it using a screw tool. Simultaneously, the screw tool should be able to follow the screwing motion axially, for which, for example, a tracking device or a length-adjustable screw shaft can be used.

[0003] From DE 10 2012 004 358 A1, a screw system is known, comprising a drive shaft rotatable with respect to its longitudinal axis and an output shaft rotatable with respect to its longitudinal axis, the rotational movement of which is coupled to the rotational movement of the drive shaft via a coupling device, wherein the output shaft has a tool holder for receiving a screwdriving tool. The coupling device couples the rotational movement of the output shaft to the rotational movement of the drive shaft and also allows axial relative movement of the output shaft with respect to the drive shaft. The coupling device may have a pneumatic drive and / or a spring element.

[0004] According to the invention, a screw system for the automated screwing in of a screw element and a method for operating the screw system with the features of the independent claims are proposed. Advantageous further developments and embodiments of the invention are described analogously for both subject matter of the invention in the dependent claims, the following description of the invention (which expressly includes optional and exemplary features), and the figure.

[0005] The screw system according to the invention for the automated screwing in of a screw element (at a screw point) has at least the following components: - a screwing tool for the screw element; - a drive device, preferably an electric motor drive device, in particular a so-called stick screwdriver, for the rotary drive of the screw tool; - a coupling device for transmitting a rotary motion generated by the drive device to the screwdriving tool, which is arranged along an axis of rotation between the drive device and the screwdriving tool, wherein the coupling device has a drive shaft and an output shaft rotatably connected to the drive shaft, i.e., rotationally fixed, wherein the drive shaft and the output shaft are arranged, in particular in alignment, along the axis of rotation and are movable relative to each other in the axial direction, i.e., along the axis of rotation.

[0006] According to the invention, the coupling device has a pneumatic suspension acting in the axial direction between the drive shaft and the output shaft, with a constant, and in particular defined, spring force. The pneumatic suspension with constant spring force ensures that, during screwing in or during a screwing operation, the contact force applied by the screwing tool to the screw element, i.e., the axial contact force, remains constant.

[0007] With the aid of the pneumatic suspension provided according to the invention, which can also be referred to as a pneumatic spring or pneumatic spring unit, the screwdriving tool can be guided along the axial screwing movement during a screwing operation. Furthermore, the pneumatic suspension can provide a constant or at least substantially constant spring or pressure force, independent of the axial relative position between the drive shaft and the output shaft. This is achieved in particular by means of a constant or at least substantially constant internal pressure, or air or gas pressure, that is independent of the spring travel. This ensures a constant or at least substantially constant contact force on the screw element during screwing, regardless of the spring travel, thereby preventing, for example, component damage at the screw point.Furthermore, a sufficiently high restoring force can be ensured throughout the entire suspension travel, especially in the end range of the rebound travel.

[0008] Preferably, the spring force and the corresponding contact force are adjustable, in particular by specifying a certain or defined internal pressure or air or gas pressure that acts in the pneumatic suspension and which may be changeable depending on the application.

[0009] Preferably, the screw system also includes a pneumatic supply unit that provides the pneumatic suspension with a constant air or gas pressure, or ensures a constant internal pressure. Preferably, the (constant) internal pressure or air or gas pressure acting in the pneumatic suspension, and thus the spring force generated in the pneumatic suspension, is adjustable, in particular continuously adjustable. The supply unit can include a pressure accumulator and / or a control valve for pressure regulation or adjustment.

[0010] The output shaft preferably has an (axial) connecting section that is guided in a piston-like and rotationally fixed manner within a cylindrical hollow section of the drive shaft. The rotationally fixed connection can be achieved via a suitable shaft-hub connection that simultaneously allows axial relative movement. Preferably, a remaining cavity of the cylindrical hollow section functions as a pneumatic pressure chamber or cylinder, for which purpose it is pressurized with a constant internal pressure, such as air or gas pressure.

[0011] Preferably, the coupling device has a rotationally decoupled housing, i.e., one that does not rotate with the drive and output shafts. The housing preferably has one connection, in particular only one (single) connection, for connection to a pneumatic supply device (so). Furthermore, the housing may have a flange or similar feature for attachment to the drive unit.

[0012] The inventive method for operating the screw system comprises at least the following steps: - Specifying an internal pressure or air or gas pressure for the pneumatic suspension, which means a defined pressure; - Placing the screwing tool on a screw element to be screwed, e.g. a screw or nut, which may result in a spring movement; - Screwing in the screw element by turning or rotating the screwing tool, whereby the (axial) clamping force applied by the screwing tool to the screw element remains constant, and wherein, if necessary, the screwing tool is guided by a spring-back movement of the axial screwing movement and / or a guiding device is used so that the screwing tool engagement can be maintained until the end of the screwing process.

[0013] The first two steps described above can also be performed in reverse order. Furthermore, it may be necessary to hold the screw element on the screwing tool beforehand.

[0014] Within the scope of the invention, both the features described above and those explained below are applicable not only in the specified combination of features, but also in other combinations or individually. This also applies to the features shown in the figure.

[0015] The invention is explained in more detail below in a non-limiting manner with reference to a figure. The features shown in the figure and / or explained below can, even independently of specific combinations of features, be general features of the invention and further develop the invention accordingly. Fig. Figure 1 shows a schematic representation of a screw system according to the invention.

[0016] The screw system 100 comprises a screw tool 110, in particular a so-called bit, a drive unit 120, and a coupling unit 130, which are connected to each other in a known manner to prevent torque. The coupling unit 130 is arranged along a common axis of rotation D between the drive unit 120 and the screw tool 110 and transmits the rotary motion generated by the drive unit 120 to the screw tool 110, optionally including a shaft extension.

[0017] The coupling device 130 has a telescopically extendable, sealed housing 131, which can be attached to the drive unit 120 via a flange 132. A drive-side drive shaft 133 and a tool-side output shaft 134 are arranged in the housing 131, supported by ball bearings or similar means, and together form a variable-length helical shaft. The output shaft 134 has an axial connecting section that is guided in a piston-like and rotationally fixed manner within a cylindrical hollow section of the drive shaft 133, so that both shafts 133 and 134 are relative to each other in the axial direction and along the axis of rotation D. The axial relative movement is limited in both directions by end stops (not shown).

[0018] The coupling device 130 is designed with a pneumatic suspension acting in the axial direction or along the axis of rotation D between the drive shaft 133 and the output shaft 134, which, according to the invention, operates with a constant spring force. This ensures that during a screwing operation, the (axial) contact force F applied in the axial direction or along the axis of rotation D by the screwing tool 110 to a screw element (not shown) remains constant or does not change.

[0019] Within the housing 131 is a pneumatic pressure chamber 137, sealed in the axial direction by means of seals 135 and 136, which are designed in particular as shaft seals. This chamber is connected to the remaining cavity 138 of the cylindrical hollow section in the drive shaft 133, so that this cylindrical cavity 138 also functions as a pneumatic pressure chamber. The pneumatic pressure chambers 137 and 138 are pressurized via a connection 139 with a constant internal pressure, in particular air or gas pressure, so that a constant spring force, independent of spring travel, acts between the drive shaft 133 and the output shaft 134.

[0020] The internal pressure or air or gas pressure is provided via a supply device 140 (only indicated), which may include a pressure accumulator 141 and a control valve 142 for pressure regulation or adjustment.

[0021] Further features and embodiments of the invention are described above. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2012 004 358 A1

[0003]

Claims

[1] Screw system (100) for automated screwing in of a screw element, comprising: - a screwdriver (110); - a drive unit (120) for the rotary drive of the screwdriver (110); - a coupling device (130) arranged along a rotational axis (D) between the drive device (120) and the screwing tool (110), comprising a drive shaft (133) and a rotatably connected output shaft (134) arranged along the rotational axis (D) and movable relative to each other in the axial direction; characterized by , that the coupling device (130) has a pneumatic suspension with constant spring force acting in the axial direction between the drive shaft (133) and the output shaft (134), so that the contact force (F) applied to the screw element by the screwing tool (110) remains constant during a screwing operation. [2] Screw system (100) according to claim 1, further comprising a pneumatic supply device (140) which supplies the pneumatic suspension with a constant air pressure. [3] Screw system (100) according to claim 2, characterized by that the air pressure is adjustable. [4] Screw system (100) according to any one of the preceding claims, characterized by , that the output shaft (134) has a connecting section which is guided in a piston-like and rotationally fixed manner in a cylindrical hollow section of the drive shaft (133), wherein a remaining cavity (138) of the cylindrical hollow section functions as a pneumatic pressure chamber. [5] Screw system (100) according to any one of the preceding claims, characterized by , that the coupling device (130) has a rotationally decoupled housing (131). [6] Screw system (100) according to claim 5, characterized by, that the housing (131) has a connection (139) for connection to a pneumatic supply device (140). [7] Screw system (100) according to claim 5 or 6, characterized by , that the housing (131) has a flange (132) for attachment to the drive unit (120). [8] Screw system (100) according to any one of the preceding claims, characterized by , that the drive device (120) is a stick screwdriver. [9] Method for operating a screw system (100) according to any one of the preceding claims, comprising the steps: - Setting an internal pressure for the pneumatic suspension; - Placing the screwing tool (110) onto a screw element to be screwed; - Screwing in the screw element, whereby the contact force (F) applied to the screw element by the screwing tool (110) remains constant.

Images