冷镦技术TECHCENTER-Colding.ppt

1、Introduction to Cold Forming,March 6, 2007 Independence, Ohio Presented by Carpenter Technology Corporation,Copyright 2007 CRS Holdings, Inc.,Introduction Terminology Processes Benefits Material Characteristics Applications Steps to Manufacture Coatings and Lubricants,The information and data presen

2、ted herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his/her own evaluation and are not intended as warranties, eit

3、her express or implied, of fitness for these or other purposes.,March 23, 1794 Josiah Pierson “Cold Header” Rivet Machine November 16, 1796 Isaac Garretson U.S. Patent for nail cutting & heading machine,History and Development of Cold Forming,Cold Forming terms: Cold Heading: cold forming process in

4、 which the force of the punch must exceed the materials elastic limit to cause plastic flow elastic limit = yield strength forging operation without the heat,Cold Forming Terminology,Cold Forming terms: Cold Extrusion decreasing the diameter of the blank by pushing it through a smaller hole reduces

5、size without yield loss Cold Forming: generic term describing the combination of cold heading with cold extrusion,Cold Forming Terminology,Applications: Cold forming machines - by the number of dies and blows for example: 1 Die/2 blow 2 Die/3 blow 2 Die/4 blow,The wire is fed in through the cut-off

6、die to a wire stop. The cut-off knife shears the blank.,The cut-off knife transfers the blank to the heading die.,Now the blank is ready to receive the first punch operation. Proper cut-off of blank is critical. Blank mass equals mass of finished part.,Upsetting of a fastener head is accomplished by

7、 using one of these 4 methods.,Typical 1-Die/2-punch method is common in producing headed fasteners. The first blow combines coning with shank extrusion. Coning is a partial head upset. The second blow finishes the head shape.,Knockout pin acts as a blank support, during heading operation. Then ejec

8、ts finished part. Rule of thumb: Unsupported pin not to exceed 8D Supported pin is recommended over 8D,Open Extrusion,Trap Extrusion,30% area reduction,75% area reduction,Examples using trap extrusion and open extrusion.,7 Station Cold Forming Process,7 Station Cold Forming Process,7 Station Cold Fo

9、rming Process,7 Station Cold Forming Process,7 Station Cold Forming Process,7 Station Cold Forming Process,7 Station Cold Forming Process,Advantages of Cold Forming Design Versatility High strength parts from non-heat-treatable alloys Most cost effective way vs. milling, machining, hobbing and chemi

10、cal etching High production rates Metallurgical Effects Grain flow Improves strength, hardness, toughness & fatigue resistance Material Savings,Benefits of Cold Forming,Heading improves the finished parts grain structure by making it conform to the flow of the design. The machined diagram shows how

11、the grain structure is weakened by cutting operations.,Benefits of Cold Forming,Materials - Characteristics,Materials - Characteristics,Materials - Characteristics,Pyromet is a reg. tm. of CRS Holdings, Inc.,Applications for Cold Formed Parts,Automotive brake parts ball joints & steering parts start

12、er pinions oxygen sensors constant velocity joints manifold bolts engine valves Appliance Industry gears fasteners for assembly,Applications for Cold Formed Parts,Construction, Off-road equipment bolts, nuts screws tapping, window, roofing, deck transmission gears similar parts for automotive Aerosp

13、ace rivets, fuselage engine bolts fasteners - landing gear, interior,Applications for Cold Formed Parts,Decision Process for Cold Forming,Equipment Material Part,which machine which tools skill of personnel formability incoming condition accuracy tolerances additional treatments,Decision Process for

14、 Cold Forming,Production of Headed Parts,Cold Heading,Hot Heading,Room TemperatureForming of heatedForging temperatures No heatslugs at temperaturesfrom 950 1250 C from: 550 950 C(1740 2300 F) (1020 1740 F),Warm Heading,Decision Process for Cold Forming,Decision Process for Cold Forming,General Aspe

15、cts of Heading Methods,Decision Process for Cold Forming,Decision Process for Cold Forming,Steps to Manufacture: From raw material to finished parts,Process Chain of Cold Forming,Raw Material Wire/Rod hot rolled shaved - seam free cf/anl material in the softest condition optimum for cold forming anl

16、/cf uniform volume uniform diameter specific incoming mechanical properties desired,Steps to Manufacture,Heat Treatment of Raw Material Benefits Improves ability of deformation Reduces hardness Improves metal structure towards better forming,Steps to Manufacture,Heat Treatment of Raw Material Types

17、of heat treatment Tempering to form spherical cementite Annealing to remove strain hardening to set the desired mechanical properties to normalize the microstructure,Steps to Manufacture,Surface Treatment Alkaline cleaning warm 170o-190oF/ 77o-88oC Cold rinsing removes alkaline cleaner Acid pickling

18、 sulphuric hydrochloric nitric/hydrofluoric Cold/warm/hot rinsing removes acids,Steps to Manufacture,Surface Treatment Pre-coating carbon zinc phosphate stainless potassium sulfate lime Drying approx. 250oF/ 120oC Metallic Coating copper plating,Steps to Manufacture,Surface Treatment Non-metallic co

19、atings molybdenum disulfide MoS2 Soaps sodium stearates calcium stearates,Steps to Manufacture,Cold Forming Single stage presses Multi stage presses up to 5 or 6 stages, as many as 8 Secondary forming operations threading rolled machined,Steps to Manufacture,Heat treatment after Cold Forming Anneali

20、ng relieve stress re-crystallize normalize Hardening increase the hardness after forming,Steps to Manufacture,Metal Removing Hard Surfaces turning grinding honing lapping Soft Surfaces turning drilling milling,Steps to Manufacture,Surface Treatment Cleaning of parts de-phosphate washing acid to remo

21、ve copper coating Corrosion protection passivation stainless steel Plating zinc chromate - Cr+6 (hexavalent chrome) can be a problem,Steps to Manufacture,Coatings Uses prevent metal to metal contact with tooling, galling act as a carrier for machine lubricants Types precoat lime copper plating zinc phosphate molybdenum disulfide oxalate,Coatings and Lubricants,Lubricants Types soaps calcium stearate sodium stearate drawing oils Metal-removing coolants oil emulsion synthetics,Coatings and Lubricants,Coatings and Lubricants,Sources: “Heading