riser design...approximated by using chvorinov’s rule riser design the modulus method where t is...
TRANSCRIPT
![Page 1: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/1.jpg)
College of Engineering
Mechanical Eng. Dept.
Riser Design
Ch5
![Page 2: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/2.jpg)
The solidification of most alloys is accompanied by appreciable volume contraction. The magnitude of this contraction which gives values for several metals forming alloys of commercial importance.
Riser Design
The purpose of a feeder head, therefore, is to provide a reservoir of liquid metal under a pressure head sufficient to maintain flow into the casting. Without feeding, the final casting will be subject to shrinkage defects in the form of major internal cavities, centre line or filamentary voids
![Page 3: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/3.jpg)
· Liquid shrinkage: The liquid metal loses volume as it gives up superheat and cools to its solidification temperature · Solidification shrinkage: The metal freezes, changing from a liquid to a higher-density solid. For pure metals, this contraction will occur at a single temperature, but for alloys it will take place over some temperature range or freezing interval · Solid shrinkage: The solid casting cools from its solidification temperature to room temperature
Riser Design
![Page 4: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/4.jpg)
The contribution of each one of the three distinct stages of volume contraction is shown: liquid shrinkage, solidification shrinkage, and solid contraction
Schematic of the shrinkage of low-carbon steel.
![Page 5: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/5.jpg)
(a) Initial liquid metal. (b) Solid skin and formation of shrinkage void. (c) Internal shrinkage. (d) Internal shrinkage plus dishing. (e) Surface puncture
(a) Initial liquid metal.
sequence of solidification shrinkage in an iron cube.
![Page 6: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/6.jpg)
(a) Open-top riser. (b) Open-top riser plus chill. (c) Small open-top riser plus chill. (d) Insulated riser. (e) Insulated riser plus chill
Methods of controlling shrinkage in an iron cube to reduce riser size
![Page 7: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/7.jpg)
Optimum Riser Design
The role of the methods engineer in designing risers can be stated simply as making sure that risers will provide the feed metal: · In the right amount · At the right place · At the right time To this list can be added several other considerations: · The riser/casting junction should be designed to minimize riser removal costs · The number and size of risers should be minimized to increase mold yield and to reduce production costs · Riser placement must be chosen so as not to exaggerate potential problems in a particular casting design (for example, tendencies toward hot tearing or distortion)
![Page 8: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/8.jpg)
Shrinkage (volume contraction)
![Page 9: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/9.jpg)
Riser Location
To determine the correct riser location, the methods engineer must make use of the concept of directional solidification.
The ability to achieve such directional solidification will depend on:
· The alloy and its mode of solidification · The mold medium · The casting design
![Page 10: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/10.jpg)
Directional and progressive solidification in a casting equipped with a riser
![Page 11: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/11.jpg)
(section width greater than 3T, where T = thickness)
Feeding distance relationships in steel plates
![Page 12: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/12.jpg)
Feeding distance relationships in steel bars (section width equal to thickness, T
Feeding distance relationships in steel plates
![Page 13: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/13.jpg)
Effect of chills on feeding distance relationships in steel bars.
![Page 14: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/14.jpg)
Riser necks used
in iron casting applications (side view and top view, respectively). (a)General type of side
riser. (b) (b) Side riser for plate
casting. (c) (c) Top round riser.
![Page 15: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/15.jpg)
The modulus method is based on the concept that the freezing time of a casting or a casting section can be approximated by using Chvorinov’s rule
Riser Design
The modulus method
where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface area of the casting, and k is the constant governed by metal and mold properties.
![Page 16: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/16.jpg)
The volume-to-area ratio of the casting is termed the casting modulus, Mc
The freezing times of risers and castings are proportional to their respective moduli, and if the modulus of the riser, Mr, is sufficiently greater than the modulus of the casting, Mc, good feeding will be obtained. In steel, if Mr = 1.2 % Mc, feeding will be satisfactory.
Mr = 1.2 % Mc
![Page 17: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/17.jpg)
Derivation of cooling modulus values. (a)Simple shapes,
![Page 18: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/18.jpg)
Derivation of cooling modulus values. Simple shapes,
![Page 19: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/19.jpg)
![Page 20: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/20.jpg)
![Page 21: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/21.jpg)
Derivation of cooling modulus values. irregular shapes,
![Page 22: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/22.jpg)
Riser configurations and their characteristic values
![Page 23: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/23.jpg)
Riser configurations and their characteristic values
![Page 24: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/24.jpg)
Riser configurations and their characteristic values
![Page 25: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/25.jpg)
Riser configurations and their characteristic values
![Page 26: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/26.jpg)
![Page 27: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/27.jpg)
![Page 28: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/28.jpg)
![Page 29: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/29.jpg)
![Page 30: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/30.jpg)
![Page 31: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/31.jpg)
![Page 32: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/32.jpg)
![Page 33: Riser Design...approximated by using Chvorinov’s rule Riser Design The modulus method where t is the freezing time of the casting, Vc is the volume of the casting, Ac is the surface](https://reader033.vdocuments.us/reader033/viewer/2022060712/607867928d3c1e6b5a1a4e54/html5/thumbnails/33.jpg)