Crosspiece Compensation System for Machine Tool Torsion
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Solution Overview
Problem
Large dimension portal machine tools with crosspieces face significant torsional stress and precision issues due to the weight of the carriage-head unit, leading to tilting and rotation of the machining axis, which existing compensation systems fail to adequately address, especially when the unit is positioned away from the uprights or when planarity errors occur.
Innovation Solution
A compensation system featuring a counter-crosspiece connected to the central portion of the main crosspiece via adjustable actuating means, such as hydraulic cylinders, which apply orthogonal compensation forces to minimize torsional deformation and correct planarity errors, ensuring the machining axis remains vertical and orthogonal to the supporting table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crosspiece structure is made stiffer to reduce torsion, then the structural strength is improved, but the device complexity and weight increase
Solution Approach 1:
The patent applies counterweight principle by using cables connected to weights that generate compensating torsion torque to balance the torsion caused by the carriage-head unit weight, allowing the crosspiece to maintain sufficient stiffness without excessive structural complexity
Solution Approach 2:
The patent introduces cables as intermediary elements that transmit the compensating force from the weights to the crosspiece, enabling torsion compensation without directly modifying the crosspiece structure itself
2Manufacturing precision
If fixed compensation systems with cables are used to balance torsion at the center position, then the torsion compensation is improved at center position, but the compensation effectiveness deteriorates when the carriage-head unit is positioned away from the center or when weight varies
Solution Approach 1:
The patent transitions from fixed compensation to dynamic compensation by making the cable tensions adjustable through winches controlled by sensors that detect the carriage-head unit position and weight, enabling real-time adaptation to different operating conditions
Solution Approach 2:
The patent implements feedback control by using sensors to detect the actual position and weight of the carriage-head unit, then adjusting the cable tensions through winches to maintain optimal torsion compensation across all positions and loading conditions
3Weight of moving object
If the crosspiece is made more flexible to reduce weight, then the device weight is reduced, but the torsion resistance deteriorates
Solution Approach 1:
The patent uses counterweight principle with cables and weights to provide active torsion compensation, allowing the crosspiece to be designed with reduced weight while the cable system compensates for the resulting increased flexibility and torsion
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 system effectively limits and adjusts torsional deformation and planarity errors, maintaining precision and optimizing machining performance by compensating for the weight and position of the operating head, regardless of its location on the crosspiece, and allows for voluntary tilting adjustments to enhance surface finish.
Implementation Method 1
a first pair of orthogonal actuating means (11, 12) arranged for exerting on said central portion (54) of the crosspiece (51) a pair of compensation forces (Fc) that generate a compensation torque (Mc)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A compensation system for a machine tool (50) provided with a crosspiece (51) supported by uprights (62, 63) and slidably supporting an operating head (60) along a first direction (Y), comprises a further crosspiece (2) having opposite ends (3, 4) fixed to side portions (52, 53) of said crosspiece (51) adjacent to said uprights (62, 63) and connected to a central portion (54) of the crosspiece (51) by actuating means (11, 12). The latter exerts on the central portion (54) a pair of compensation forces (Fc) that are adjustable and such as to generate on the crosspiece (51) compensation torque (Mc) that is able to limit and/or control a rotation and/or a tilting of the operating head (60), in particular following a torsional deformation of the crosspiece (51) caused by the weight of said operating head (60).