Compensating Shaft-Hub Coupling for High-Torque Screw Feed
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Solution Overview
Problem
Conventional screwing devices experience high wear and difficulty in controlling feed force due to high frictional forces at the shaft-hub connection, especially under high torque loads, requiring powerful feed drives and leading to increased costs and complexity.
Innovation Solution
A screwing device with a compensating coupling that allows joint axial movement of the shaft and hub relative to the rotary drive when torque exceeds a certain threshold, using a rolling element and spring element to reduce friction and maintain torque transmission, thereby protecting the shaft-hub connection from wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shaft-hub connection is used to enable axial displacement of the drive torque transmission unit, then the bit and screw can perform feed motion relative to the rotary drive, but high frictional forces cause high wear on the shaft-hub connection under high torque loads
Solution Approach 1:
A compensating coupling is introduced as an intermediary element between the shaft and hub. This compensating coupling includes a compensating element that can axially displace relative to the shaft, absorbing the axial movement requirements and preventing direct frictional contact between the shaft and hub, thereby reducing wear while maintaining feed motion capability
Solution Approach 2:
The drive torque transmission unit is segmented into distinct components: the shaft, the compensating coupling with compensating element, and the hub. This segmentation allows the compensating element to independently handle axial displacement while the shaft-hub connection focuses on torque transmission, separating the functions and reducing相互 interference
2Ease of operation
If high frictional forces are present at the shaft-hub connection, then a powerful feed drive is required to achieve axial displacement, but this leads to higher costs and increased device complexity
Solution Approach 1:
The compensating coupling acts as a mechanical intermediary that facilitates axial displacement through the relative movement of its compensating element, reducing the burden on the feed drive system and eliminating the need for overly powerful or complex feed drive mechanisms
Solution Approach 2:
The compensating coupling introduces dynamic flexibility to the drive torque transmission unit, allowing it to adapt its effective length during operation. The compensating element can axially displace to accommodate feed motion requirements, enabling the system to handle varying torque conditions without requiring a permanently oversized feed drive
3Productivity
If the shaft-hub connection is subjected to high torque during thread forming, then high feed force is required to overcome static friction, but the feed force required drops significantly once static friction is overcome, making feed force control difficult
Solution Approach 1:
The compensating coupling serves as a mediator that decouples the feed force application from the shaft-hub friction interface. By providing an alternative path for axial displacement through its compensating element, it smooths out the feed force requirements and eliminates the abrupt transitions caused by static friction breakthrough
Solution Approach 2:
The compensating coupling changes the mechanical parameters of the system by introducing a new degree of freedom for axial movement. This alters the force-displacement characteristics, transforming the feed force profile from one with abrupt changes to one that is more continuous and controllable throughout the thread forming process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compensating coupling reduces wear and simplifies feed force control by minimizing friction between the shaft and hub, especially under high torque conditions, enhancing the device's durability and operational efficiency.
Implementation Method 1
A screwing device (10) has a rotary drive (14) for rotating the screw (5). The screwing device (10) has a feed drive (32) to move the bit (15) and thus the screw (5) in the feed direction, i.e., in the axial direction.
Implementation Method 2
A compensating coupling (20) is provided, which allows a joint axial movement of the shaft (24) and the hub (28) relative to the rotary drive (14) when the torque load exceeds the first torque load range
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
The invention relates to a screwing device for setting a screw. The screwing device comprises a rotary drive for rotating the screw, an advancing drive for generating an axial advancing force on the screw, and a shaft/hub unit comprising a driveshaft, which has a non-round cross-section, and a hub, which is rotationally fixed to the driveshaft. The driveshaft and the hub are used to contribute to a torque provided by the rotary drive. In the process, the driveshaft and the hub are movable relative to each other within a first torque loading range in order to allow an axial advancing movement of the screw relative to the rotary drive. In order to reduce the wear in the shaft/hub unit, a compensation coupling is provided which allows a common axial movement of the shaft and the hub relative to the rotary drive in the event of a torque load which is increasing over the torque loading range.