Helical Vent Channel Ram for Powered Hammer Manufacturing

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Solution Overview

Problem

The manufacturing of the ram for powered hammers is costly due to the need for multiple machining steps, including machining a blank and then an axis parallel vent channel in the outer circumferential surface.

Innovation Solution

The vent channel on the outer circumferential surface of the ram is helically shaped, allowing it to be produced in a single step on the same machine tool used for surface machining, with a constant pitch helix facilitating this process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the vent channel is machined as an axis parallel channel in a separate machine tool after blank machining, then the vent channel can be produced with required precision, but the manufacturing cost and process complexity increase due to multiple machining steps

Engineering Contradiction:
Improvevent channel precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines the blank machining operation and the vent channel machining operation into a single machining process. The vent channel is machined at an angle relative to the blank axis during the same machining setup, eliminating the need for a separate machine tool and operation. This merging of operations reduces manufacturing cost while maintaining the required precision through proper toolpath planning and fixture design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Instead of machining the vent channel in the conventional axis-parallel direction (one-dimensional approach), the patent machines the vent channel at an angle relative to the blank axis. This angular approach introduces a new dimensional orientation that allows both the blank features and vent channel to be created in a single setup, reducing the number of machining steps while preserving precision requirements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If multiple machining steps are used to produce the ram, then the manufacturing precision can be maintained, but the productivity decreases due to longer manufacturing time

Engineering Contradiction:
Improveram surface precisionVSAvoidmanufacturing throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges multiple machining operations into a single continuous machining process. The blank is machined and the vent channel is created in one setup without removing the workpiece from the machine tool. This consolidation maintains manufacturing precision through consistent fixture positioning and tool calibration while significantly improving productivity by eliminating transfer time and setup time between operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary positioning and setup of the blank in the machine tool before both machining operations begin. The fixture is pre-configured to hold the blank in the correct orientation for both the blank machining and the angled vent channel machining. This preliminary action ensures that precision requirements are met while enabling both operations to proceed in sequence without interruption, thereby improving overall manufacturing throughput.

Inventive Principle:
Principle #10Preliminary action

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 simplifies the manufacturing process by enabling the production of the vent channel and other surface features in a single operation, reducing costs and complexity.

Implementation Method 1

the piston in operation generates a varying air cushion between the ram and the piston surface facing the ram to thereby cause an impact on a tool bit

Methodology Applied
Scientific EffectAir cushion: Air Lubrication

Implementation Method 2

the space between the ram and the surface of the piston facing the ram is temporarily connected to atmosphere through the vent channel and a recess in the wall of the guide tube section

Methodology Applied
Scientific EffectPressure venting: Pressure Drop

Data Source

PatentEP1825963B1Powered hammer
Publication Date: 2013.11.06 BLACK & DECKER CORP
  • EP1825963B1 patent drawingFigure 1
  • EP1825963B1 patent drawingFigure 2
  • EP1825963B1 patent drawingFigure 3

AI summary

A powered rotary hammer or chisel hammer has a hammer mechanism with a ram (20) reciprocatingly movably mounted in a guide tube section (15) and comprising an outer circumferential surface in which a vent channel (24) is provided which connects the front end of the circumferential surface with its rear end and which is interrupted by a radially outwardly projecting sealing portion (22), and has a piston (13) reciprocatingly drivable by means of a motor of the hammer which piston in operation generates a varying air cushion between the ram (20) and the piston surface facing the ram to cause an impact on the tool bit inserted into the tool holder (10) of the hammer by movement of the ram (20) towards the tool bit wherein the space between the ram (20) and the surface of the piston (13) facing the ram (20) is temporarily connected to ambient air through the vent channel (24) after causing the impact. The vent channel (24) on the outer circumferential surface of the ram (20) is helically shaped.