Servo Spot Welding Gun Rotor Encoder Parallel Offset
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Solution Overview
Problem
Conventional electric spot welding guns face challenges in reducing the overall length of the motor drive unit due to the axial length added by the encoder and shaft bushing, which restricts the miniaturization of the device.
Innovation Solution
The motor drive unit is redesigned with the rotor and encoder disposed in parallel, offset relative to the push rod, and pressing guides installed on both sides, allowing for a shorter axial length and improved rigidity, while the equalizing mechanism and flexible conductor are positioned to reduce load and exposure to sputter, enabling direct connection to the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the encoder is connected in series to the rear of the rotor, then the rotation of the rotor can be detected, but the overall length of the motor drive unit increases
Solution Approach 1:
The encoder is repositioned from a series connection at the rear of the rotor to a parallel arrangement in the radial direction. The encoder's detection axis is oriented radially outward from the rotor center, allowing it to detect rotor rotation without extending the axial length of the motor drive unit. This dimensional reconfiguration resolves the contradiction between achieving accurate rotation detection and maintaining a compact overall length.
2Stability of the object's composition
If the shaft bushing is disposed at a forward portion of the motor drive unit to receive the moment acting on the push rod, then the pushing operation can be stabilized, but the overall length of the motor drive unit increases
Solution Approach 1:
The shaft bushing is positioned within the motor drive unit housing rather than extending outward at the forward portion. The bushing is nested inside the available radial and axial space of the motor drive unit, allowing it to receive the moment acting on the push rod without increasing the overall external dimensions of the motor drive unit. This nesting approach maintains pushing stability while avoiding length increase.
3Adaptability or versatility
If the press point is offset from the push rod to accommodate various workpiece shapes, then the welding gun becomes more versatile, but the moment acting on the push rod increases
Solution Approach 1:
A moment reaction mechanism is introduced as an intermediary between the offset press point and the push rod. This mechanism includes reaction surfaces and structural elements that transfer and balance the moment generated by the offset pressing force, preventing it from being fully transmitted to the push rod. The intermediary structure allows the press point to be offset for versatility while protecting the push rod from excessive moment loads.
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
This configuration effectively shortens the motor drive unit's length, enhances rigidity, reduces component count, and extends the life of the flexible conductor by minimizing exposure to welding sputter and direct connection to the transformer, leading to a more compact and durable electric spot welding gun.
Implementation Method 1
a feed screw mechanism configured by a ball screw and a nut
Data Source
AI summary
An electric spot welding gun (10) includes: a servo motor (40); a push rod (50) that advances and retracts in response to rotation of a rotor (43) of the servo motor; a drive-side electrode tip (71) that is mounted to a drive-side arm (70) fixed to a leading end of the push rod; and an encoder (60) that detects the rotation angle of the rotor of the servo motor, the position of the electrode tip being offset relative to the push rod, in which the rotor and the encoder are disposed in parallel to each other in an offset plane on which the electrode tip is offset relative to the push rod, at an attitude in which a trailing end (44) of the rotor on a side opposite to a push rod side thereof and an input end (64) of the encoder are facing in the same direction.