Toggle Lever Clamping Unit Drive Segmentation
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Solution Overview
Problem
Existing toggle-lever clamping units in injection molding machines face inefficiencies due to high transmission ratios requiring long crosshead travel for closing force buildup, varying force requirements across phases, and mechanical weaknesses in spindle-nut drives, leading to suboptimal drive design and increased dry run time.
Innovation Solution
The implementation of additional drives that allow connecting levers to move orthogonally relative to the crosshead and have variable length, enabling separate optimization for traversing and force-generating tasks, reducing dry run time and improving energy utilization by allowing independent design of drives for each phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high transmission ratio is used in the force-transmitting lever pairs, then the closing force can be built up effectively, but a long travel of the crosshead is required which increases the dry run time
Solution Approach 1:
The closing force generation is segmented into two independent phases: (1) crosshead traversal phase using a traversing drive for rapid positioning, and (2) force buildup phase using a separate force-generating drive (such as a short-stroke cylinder or spindle-nut mechanism) that acts on the connecting lever to extend the main lever. This segmentation allows each drive to be optimized for its specific function, reducing overall cycle time while maintaining effective closing force.
Solution Approach 2:
The system dynamically transitions between two drive modes: during the opening/closing traversal, the traversing drive operates at high speed with minimal force; during the force buildup phase, the force-generating drive engages to provide high force with minimal travel. This dynamic switching resolves the contradiction by adapting the drive characteristics to the instantaneous operational requirements.
2Speed
If the crosshead drive is designed for fast traversing movements with little effort, then the traversing speed is improved, but it cannot generate the high force required for closing force buildup
Solution Approach 1:
The drive system is segmented into two independent drives: a traversing drive (e.g., hydraulic cylinder or electric motor) optimized for high-speed crosshead movement with minimal force, and a separate force-generating drive (e.g., short-stroke cylinder, spindle-nut mechanism, or eccentric drive) optimized for high-force generation with minimal travel. Each drive performs its specialized function without compromise.
Solution Approach 2:
The connecting lever serves multiple functions: it transmits the traversing motion from the crosshead during opening/closing movements, and it serves as the actuation point for the force-generating drive during closing force buildup. This multi-functionality allows the system to achieve both fast traversing and high force generation through a unified mechanism.
3Device complexity
If a single drive is used for both traversing and force generation, then the device complexity is reduced, but the drive cannot be ideally designed for both phases
Solution Approach 1:
The drive system is divided into two specialized subsystems: a traversing drive for rapid crosshead positioning and a force-generating drive for closing force buildup. Although this increases component count, each subsystem can be minimized in size and complexity since it performs only one function. The overall system efficiency improves significantly due to the optimal design of each subsystem for its specific task.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a toggle lever clamping unit for an injection molding machine, wherein the cross clamp (5) can be linearly moved along the longitudinal axis (A) of the machine by way of a first drive (30, 40). In order to be able to downsize said drive, according to the invention, one or several additional drives (8, 9) are provided between the cross clamp (5) and the primary levers (3a, 3b; 4a, 4b), which drives are operationally connected to the connecting levers (6, 7). By way of said drives, the connecting levers (6, 7) can be moved essentially in a direction that is orthogonal to the longitudinal axis of the machine (A) relative to the cross clamp (5) and/or relative to the primary levers (3a, 3b; 4a, 4b), in order to make it possible to put the primary levers (3a, 3b; 4a, 4b) in the fully extended position, and/or that length-adjustable connection levers (6', 7') are provided between the primary levers (3a, 3b; 4a, 4b) and the cross clamp (5), wherein for each of the connecting levers (6', 7'), at least one additional drive (20, 21) is provided, with which the length of the respective connecting lever (6', 7') can be adjusted in order to make it possible to put the primary levers (3a, 3b; 4a, 4b) in the fully extended position.