Pneumatic Cylinder Weight Balancing for CMM Stick-Slip Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gantry coordinate measuring machines face issues with weight balancing of vertically mobile members, leading to motor oversizing and safety concerns due to unbalanced weight, and existing pneumatic cylinder balancing devices suffer from friction-induced 'stick-slip' motion instability, especially in continuous surface scanning modes.
Innovation Solution
A weight balancing device using a pneumatic cylinder with a piston and stem connected to a suspension assembly featuring damping rings and a helical spring, which reduces friction and motion instability by using elastic suspension and damping to counteract adhesion forces, allowing the measuring head to move vertically while minimizing stick-slip effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-acting pneumatic cylinder with seal is used to balance the weight of the measuring head, then the weight balancing function is achieved, but friction between the seal and liner causes stick-slip motion instability
Solution Approach 1:
The patent introduces an elastic element (spring) as an intermediary between the piston and the measuring head. This spring mediator absorbs the friction effects between the seal and liner, converting the direct friction-coupled rigid connection into a compliant connection that filters out stick-slip disturbances, thereby maintaining motion stability while preserving weight balancing functionality
Solution Approach 2:
The patent changes the mechanical parameter of the connection between the piston and measuring head from rigid to compliant by introducing elastic deformation capability. This parameter change allows the system to accommodate friction-induced displacements without transmitting them as motion instability to the measuring head
2Stability of the object's composition
If high precision cylinders with no seals are used to eliminate friction, then stick-slip phenomena are reduced, but the device becomes extremely costly and difficult to find
Solution Approach 1:
Instead of eliminating the seal entirely (which would require expensive precision cylinders), the patent introduces a spring intermediary that compensates for the seal's friction effects. This allows the use of commercially available, cost-effective sealed cylinders while achieving motion stability comparable to sealless precision cylinders
Solution Approach 2:
The patent replaces the expensive, difficult-to-find sealless precision cylinder with a combination of inexpensive sealed cylinder and simple spring element. This substitution uses readily available, low-cost components to achieve the same functional outcome
3Device complexity
If the weight of the measuring head is not balanced, then the motor can be smaller, but the motor must be oversized to handle unbalanced weight or alternative safety systems are required
Solution Approach 1:
The patent implements a pneumatic cylinder-based counterbalancing system that generates an upward force equal to the weight of the measuring head. This anti-weight mechanism allows the motor to only overcome friction and acceleration forces, significantly reducing motor size while maintaining operator safety through controlled, balanced operation
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 solution effectively balances the weight of the measuring head, reducing motor requirements, eliminating stick-slip phenomena, and maintaining precise position control during continuous scanning, while also reducing the need for high-cost precision cylinders.
Implementation Method 1
By supplying compressed air into the cylinder, it is possible to balance the weight of the measuring head via the pressure force
Implementation Method 2
A weight balancing device using a pneumatic cylinder with a piston and stem connected to a suspension assembly featuring damping rings and a helical spring
Implementation Method 3
A weight balancing device using a pneumatic cylinder with a piston and stem connected to a suspension assembly featuring damping rings
Data Source
AI summary
A measuring machine comprising a measuring column, which can move vertically with respect to a carriage, and a device for balancing the weight of the column, which is provided with a pneumatic cylinder having its liner fixed to the column and the stem constrained to a supporting structure, carried by the carriage via an elastic-suspension assembly that enables the stem to follow the liner in the case of adhesion and to return into a position of equilibrium when the elastic reaction of the elastic-suspension assembly overcomes the force of friction between the piston and the liner; stick-slip phenomena are thus neutralized.