Two-Step Bolt Setting for Low-Force Robotic Joining
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Solution Overview
Problem
Existing bolt setting methods for nail-shaped bolts, which involve high-speed rotation-free straight-line movements, result in noise pollution and high mechanical loads on robots, making it difficult to implement these methods using lower-cost industrial robots due to excessive reaction forces.
Innovation Solution
A two-step bolt setting method where the bolt is first driven into the component with a deforming stroke at a low speed (≤4 m/s) to penetrate fully and then completed with a friction stroke, reducing energy consumption and reaction forces, and a setting device with an electronic control unit is used to manage the process, allowing for precise kinetic energy adaptation and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed bolt setting methods are used to achieve effective joining, then joining speed and connection quality are improved, but reaction forces on robots and delivery devices increase significantly
Solution Approach 1:
The bolt setting process is divided into multiple phases: an acceleration phase where the bolt is accelerated to joining speed, and a setting phase where the bolt is driven into the workpiece. This segmentation allows the acceleration to occur over a longer period before impact, reducing peak reaction forces on the robot while maintaining effective joining speed during the actual setting operation.
Solution Approach 2:
The bolt is pre-accelerated to the required joining speed before making contact with the workpiece. This preliminary acceleration allows the bolt to gain kinetic energy gradually through a longer acceleration path, reducing the impulse force transmitted to the robot during the setting operation.
2Reliability
If high joining speeds are used for effective bolt setting, then connection quality is guaranteed, but noise pollution increases
Solution Approach 1:
The setting process is segmented into acceleration and setting phases, allowing the bolt to accelerate quietly over a longer path before impact. The actual setting occurs at controlled speed, reducing noise from sudden impacts while maintaining connection quality through the accumulated kinetic energy of the pre-accelerated bolt.
Solution Approach 2:
The bolt is pre-accelerated to joining speed before contact with the workpiece, allowing kinetic energy to be accumulated gradually. This preliminary action reduces noise during the setting operation by eliminating sudden accelerations and impacts, while still achieving effective joining through the pre-acquired kinetic energy.
3Productivity
If high-speed bolt setting is implemented, then joining effectiveness is improved, but the robot stability requirements and costs increase
Solution Approach 1:
The process is divided into acceleration and setting phases, allowing the robot to operate at lower speeds during acceleration (reducing stability requirements) while still achieving effective joining through the pre-accelerated bolt's kinetic energy during the setting phase.
Solution Approach 2:
The bolt is pre-accelerated to joining speed before contact, transferring the speed requirement from the robot to the bolt itself. This allows the use of lower-cost, less stable robots that cannot maintain high speeds throughout the entire setting process, while still achieving effective joining through the pre-accelerated bolt.
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 method reduces noise pollution and mechanical loads on robots, enabling the use of lower-cost industrial robots by minimizing reaction forces and optimizing energy consumption during the bolt setting process.
Implementation Method 1
accelerating a driver piston with a driver piston mass to a predetermined joining speed, so that the bolt is joined into the at least one component by the kinetic energy of the driver piston
Implementation Method 2
the shaft completely penetrates the at least one component with a portion of a maximum diameter with respect to a shaft length
Data Source
AI summary
A bolt setting method and device for a nail-shaped bolt with a head and a shaft, ending in a tapered manner. The bolt setting method includes: joining the bolt into a component with a deforming stroke during which the bolt reaches a first joining speed of ≤4 m/s and the shaft completely penetrates the components with a portion of a maximum diameter with respect to a shaft length, without a bottom side of the head abutting the at least one component, and after the deforming stroke, driving the bolt into the at least one component until a head abutment of the bottom side of the head on the at least one component by at least one friction stroke with which a frictional connection between the shaft and the components is overcome and with which the bolt reaches a second joining speed that is smaller than the first joining speed.