Connecting Element Forming with a Single Die to Prevent Twisting

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Solution Overview

Problem

Existing methods for producing rotary driving surfaces and locking grooves in metal connecting elements require multiple dies, leading to high production costs and limitations in part lengths and diameters, as well as issues with part twisting during processing, resulting in machine downtimes and tool damage.

Innovation Solution

The method involves forming rotary driving surfaces and locking grooves in a single die using radially movable deformable bodies, with an optional inner pin to reduce the tubular inner cross-section, and employing a wedge mechanism for compact device design and reduced ejection forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple dies are used to form rotary driving surfaces and locking grooves, then the manufacturing precision and reliability are improved, but the device complexity and production costs increase

Engineering Contradiction:
Improveforming precisionVSAvoidmulti-stage press complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple forming operations (rotary driving surface formation and locking groove formation) into a single die. The die contains multiple forming bodies that can simultaneously or sequentially create different features on the connecting element, eliminating the need for multi-stage presses and reducing device complexity while maintaining manufacturing precision.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single die is designed to perform multiple functions: forming rotary driving surfaces, creating locking grooves, and positioning the workpiece. This multi-functional die replaces several specialized dies, reducing overall system complexity while preserving the precision of each individual forming operation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If multiple dies are used for sequential forming operations, then the manufacturing precision is improved, but the productivity decreases due to increased processing time

Engineering Contradiction:
Improveforming precisionVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Multiple forming operations are merged into a single die, allowing simultaneous or sequential formation of rotary driving surfaces and locking grooves in one processing step. This eliminates the time required to transport the workpiece between multiple dies, significantly increasing productivity while maintaining the precision of each forming operation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single die enables continuous forming operations without interruption for workpiece removal and repositioning. The forming bodies can operate simultaneously or in rapid sequence, maintaining continuous useful action and eliminating idle time associated with multi-stage processing.

Inventive Principle:
Principle #20Continuity of useful action

3Ease of manufacture

If locking grooves are formed first, then the ease of manufacture is improved, but the reliability decreases due to part twisting during subsequent operations

Engineering Contradiction:
Improveprocessing easeVSAvoidpart stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The die incorporates positioning elements that securely hold the workpiece in the correct orientation before forming operations begin. This preliminary positioning prevents twisting during subsequent forming operations, ensuring both ease of manufacture and high reliability by eliminating workpiece movement during processing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The die design includes counteracting forces or constraints that prevent the workpiece from twisting during forming. By anticipating and counteracting the twisting tendency before it occurs, the system maintains part stability throughout the forming process while allowing easy formation of features.

Inventive Principle:
Principle #9Preliminary anti-action

4Productivity

If a single die is used for all forming operations, then the productivity increases and device complexity reduces, but the manufacturing precision may deteriorate

Engineering Contradiction:
Improveproduction efficiencyVSAvoidforming precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The single die is segmented into multiple independent forming bodies, each responsible for a specific forming operation. This segmentation allows each forming body to be optimized for its specific function while operating within the unified die structure, maintaining high precision for each feature while achieving the productivity benefits of a single-stage process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the die are designed with locally optimized characteristics suitable for specific forming operations. Each forming body has geometry and material properties tailored to its specific function, ensuring high precision for each type of feature formed while maintaining overall system simplicity and productivity.

Inventive Principle:
Principle #3Local quality

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 approach reduces production costs, prevents part twisting, and allows for the manufacture of a wider range of drill and chisel dimensions, enhancing the durability of forming tools and the quality of suction drills.

Implementation Method 1

the at least one or more locking sinks are embossed into the semi-finished connecting element by radial infeed of one or more deformable bodies that are movable in the die

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

at least one wedge is arranged outside the die and approximately at right angles to the longitudinal die opening, which wedge presses on the at least one radially movable forming body

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP3639947B1Method and device for producing a connecting element
Publication Date: 2021.03.24 MAC PANTHER
  • EP3639947B1 patent drawingFigure 1
  • EP3639947B1 patent drawingFigure 2~7
  • EP3639947B1 patent drawingFigure 3~11

AI summary

The invention relates to a method and a device for producing a rod- or tube-shaped intermediate product provided with an end surface (106) from a metal connecting element semi-finished product (102), in particular an axially movable end of a drill bit or chisel which is axially movable in a tool holder of a rotary hammer, wherein the connecting element (100') has at least one drive surface (162, 164) and at least one locking recess (122, 124), wherein the locking recess (122, 124) is preferably designed as a locking groove, wherein a connecting element semi-finished product (102) is provided, wherein the at least one drive surface (162,164) is formed into the fastener semi-finished product (102) by axially inserting the fastener semi-finished product (102) under force in the direction of the longitudinal axis (136) of the fastener semi-finished product (102) into a longitudinal die opening (204) of a die (202) or is impressed into the fastener semi-finished product (102) by radially advancing at least one movable forming body (206), and the at least one locking recess (122, 124) is impressed into the fastener semi-finished product (102) by radially advancing at least one or more forming bodies (206) movable in the same die (202).