US3247766A - Process for machining tubular elements with fins for heat exchangers - Google Patents

Process for machining tubular elements with fins for heat exchangers Download PDF

Info

Publication number
US3247766A
US3247766A US350421A US35042164A US3247766A US 3247766 A US3247766 A US 3247766A US 350421 A US350421 A US 350421A US 35042164 A US35042164 A US 35042164A US 3247766 A US3247766 A US 3247766A
Authority
US
United States
Prior art keywords
fins
axis
machining
row
mill
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US350421A
Other languages
English (en)
Inventor
Maillet Ennemond
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Application granted granted Critical
Publication of US3247766A publication Critical patent/US3247766A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/06—Casings; Jackets
    • G21C3/08—Casings; Jackets provided with external means to promote heat-transfer, e.g. fins, baffles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C3/00—Milling particular work; Special milling operations; Machines therefor
    • B23C3/28—Grooving workpieces
    • B23C3/34—Milling grooves of other forms, e.g. circumferential
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C5/00—Milling-cutters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
    • F28F1/34—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending obliquely
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T409/00—Gear cutting, milling, or planing
    • Y10T409/30—Milling
    • Y10T409/303752—Process

Definitions

  • the present invention relates to a process for machining tubular elements for heat exchangers of the type wherein the external surface which is in contact with a flow of cooling fluid is provided with fins, and especially for the fabrication of fuel element cans for nuclear reactors.
  • the invention is more especially concerned among cans of this type with those which are provided with adjacent rows of oblique and parallel fins forming a herringbone pattern, that is to say in which the fins of each row are inclined to the axis of the can and have an opposite angle of slant with respect to the fins of each adjacent row, said cans having preferably a circular transverse cross-section.
  • the fins induce convection currents in the flow and these latter periodically renew the fluid which is in contact with the can, especially within each unitary groove or channel which is formed between two successive fins.
  • the convection currents thus formed have a generally spiral flow pattern and are substantially symmetrical.
  • the said currents are distributed around the can and follow vortical flow paths which are oriented in independent streams, thereby providing an appreciable improvement in the heat transfer coefficient.
  • the intensity of heat extraction is dependent on the number of recycling processes and on the rate of flow between the fins, and increases with the angle at which the fins are inclined to the longitudinal axis of the can.
  • This angle of inclination which can advantageously be increased to 45 and over, is nevertheless limited by the pressure loss within the flow and by the aerodynamic stresses which are liable to accelerate the processes of heat distortion of the fins.
  • the primary object of the present invention is to define an effective configuration which can be achieved by means of a process which is both particularly simple and easy to carry into effect.
  • the process in accordance with the invention is accordingly characterized in that itconsists in machining the fins of each row by means of milling-cutter teeth having the shape of the transverse cross-section of the unitary channels formed between two successive fins in a same row, the said teeth being parallel to each other and grouped together in such a manner as to form a hollow end-mill, the axis of which makes a constant angle with the axis of the tubular element.
  • the said constant angle is chosen in such manner that the fin surfaces are inclined towards the downstream end of the fluid flow which is in contact with the element.
  • the axis of the hollow end-mill does not intersect the axis of the tubular element and the distance between these two axes, that is' to say the length of their common perpendicular, is maintained constant at the time of successive machining of each parallel fin of a same row.
  • FIGS. 1, 2 and 3 are partial views showing fins which have been machined in a tubular element or nuclear fuel can, said fins being shown respectively in cross-section in a plane at right angles to the axis of the can (FIG. 1), in perspective (FIG. 2) and in projection on a plane passing through the axis of the can (FIG. 3).
  • FIG. 4 represents diagrammatically a perspective view of a can and of a hollow end-mill which serves to form curved fins in accordance with the process which is contemplate-d.
  • FIGS. 5 and 6 arerespectively views in perspective and in projection in a plane at right angles to the axis of the can which is illustrated in FIG. 4. i
  • the can body 1 is provided on its external surface with rows of parallel fins such as the fin 2 which are shown in cross-section in a plane at right angles to the longitudinal axis of the said can.
  • the said fins 2 are formed by hollowing out in the thickness of the body 1 channels or grooves such as the groove 3 by means of a series of suitable milling-cutter teeth 4 which are mounted in such manner as to form a hollow endmill F, one particular form of embodiment of which is illustrated in FIG. 4.
  • the said hollow end-mill which is in itself of conventional type, comprises a number of teeth 4 which are parallel to each other and inserted at intervals in a circular ring or annulus F1.
  • Each tooth or bit 4 is made integral with the ring whereas this latter is mounted to rotate about the axis A--A of the end-mill; the different mechanical components which produce the rotary motion of the end-mill have been omitted from the drawings.
  • the end-mill F cuts the can 1 in a given direction which is defined by the angle ,6 which is made between the axis A-A' of the end-mill and the axis XX of the can, said angle being maintained constant at the time of machining of all the successive fins of a same row on the external surface of the can 1.
  • the tips of the milling-cutter teeth 4 move in a circle having a radius which is equal to that of the ring F1, said circle being projected at right angles on the plane of FIG. 1 in an ellipse B.
  • the profiles of the channels 3 between the fins accordingly widen progressively as shown, for example, by the channels 3 and 3a of FIG. 1. Similarly, a slight increase both in the height and depth of said fins takes place progressively as the milling-cutter moves forward.
  • the axis A--A of the end-mill is displaced relatively to the center of the circular rod 5 which is surrounded by the can 1 and which consequently does not intersect the axis X-X' of this latter.
  • the distance d between these two axes which measures the length of their common perpendicular thus defines the angle 3 which is made between the axes A-A' and X-X and the exact position of the end-mill F with respect to the can 1 for the purpose of machining fins in any row, the transition from one fin to the next being carried out by means of a single movement of translation of the millingcutter as a whole in a direction parallel to that of the axis X-X'.
  • the transition from one row of fins to the adjacent row for the purpose of forming a herringbone pattern is brought about by tilting the axis AA' of the end-mill so as to give this latter a position which is symmetrical with that which it had previously occupied with respect to the plane which passes through the axis X of the can and through the generator-line of this latter which separates the two rows of fins considered.
  • the edges of the fins 2 are also projected in curves which are similar to ellipses as can be seen from the external view which is illustrated in FIG. 2.
  • the flow lines which are followed by the cooling fluid have a pattern which is shown diagrammatically by the arrow C.
  • the machining of the curved fins having circular director-lines endow said fins with a configuration in the form of rounded herringbones with a slight slant at the point of admission of the fluid into the unitary channels formed between two successive fins and a distinctly sharper angle of slant at the exit.
  • this angle of slant with respect to the longitudinal axis of the can can be comprised between 15 and 30 at the fin-channel entry and between 40 and 70 at the fin-channel exit.
  • FIG. 3 additionally shows the angle of inclination of the fins which is neces-.
  • the angle 'y of inclination of the axis AA relatively to a direction N--N' which is normal to the axis of the element must be at least equal to 10 in the direction which tends to incline the fin surfaces towards the downstream end of the fluid flow.
  • This angle of inclination in fact permits the possibility of achieving a better discharge of fluid from the fin channels 3 along the flow lines which are shown diagrammatically by the arrow C.
  • the said angle of inclination must not be greater than 30 in order that the depth of the fin channels should not be made excessive when the fins are of suitable height.
  • the diagrammatic FIGURE is a view in elevation of the can which is illustrated in FIG. 4 and shows partially two rows of symmetrical curved fins 2, corresponding to the transverse cross-section which is shown in FIG. 6.
  • the fuel rod 5 is shown in its entirety as surrounded by its can 1, the fins 2 of this latter being separated by longitudinal grooves 7 and 8 forming recesses which .are necessary for the purpose of freeing the teeth of the end-mill F and which also facilitate the admission of fluid within the fin channels 3 and the discharge of said fluid from these latter.
  • Longitudinal partition walls 9 can also be advantageously provided between said grooves so as to center the can with respect to a structure (which has not been shown in the drawings) which surrounds said can and especially within the fuel channel of a nuclear reactor.
  • the external contour of the fins is determined by a circle or by a polygon, the shape of which can be produced directly by extrusion of a blank in which the recesses for the admission and discharge of fluid are formed in the manufacturing process and which is then employed as starting material for the machining of fins according to the arrangements which have ben set forth hereinabove.
  • the invention is not limited in any sense to the form of embodiment which has been dscribed and illustrated and which has been given solely by way of example.
  • the configuration of the fins in accordance with the process of the invention could give rise to shapes and dimensions which can be variable as a function of the number of rows of fins.
  • the optimum dimensions of the fin channels are of the order of one millimeter in width and one centimeter in depth.
  • the thickness of each fin is also of the same order of magnitude as the width of each channel but can decrease to a more or less marked extent towards the tips of the fins.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Thermal Sciences (AREA)
  • Plasma & Fusion (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Milling Processes (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
US350421A 1963-03-21 1964-03-09 Process for machining tubular elements with fins for heat exchangers Expired - Lifetime US3247766A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR928830A FR1405807A (fr) 1963-03-21 1963-03-21 Procédé d'usinage d'éléments tubulaires à ailettes pour échangeurs de chaleur

Publications (1)

Publication Number Publication Date
US3247766A true US3247766A (en) 1966-04-26

Family

ID=8799800

Family Applications (1)

Application Number Title Priority Date Filing Date
US350421A Expired - Lifetime US3247766A (en) 1963-03-21 1964-03-09 Process for machining tubular elements with fins for heat exchangers

Country Status (7)

Country Link
US (1) US3247766A (is")
BE (1) BE645512A (is")
CH (1) CH408842A (is")
FR (1) FR1405807A (is")
GB (1) GB1000270A (is")
LU (1) LU45633A1 (is")
NL (1) NL6403036A (is")

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631758A (en) * 1969-08-22 1972-01-04 Ind Modulator Systems Corp Process for grooving fluid-bearing bars, and resulting articles
US10702931B2 (en) * 2016-05-19 2020-07-07 Kanefusa Kabushiki Kaisha Dimple processing method using rotary cutting tool

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH625611A5 (is") * 1978-03-15 1981-09-30 Sulzer Ag

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631758A (en) * 1969-08-22 1972-01-04 Ind Modulator Systems Corp Process for grooving fluid-bearing bars, and resulting articles
US10702931B2 (en) * 2016-05-19 2020-07-07 Kanefusa Kabushiki Kaisha Dimple processing method using rotary cutting tool

Also Published As

Publication number Publication date
LU45633A1 (is") 1964-05-11
FR1405807A (fr) 1965-07-16
GB1000270A (en) 1965-08-04
BE645512A (is") 1964-07-16
CH408842A (fr) 1966-03-15
NL6403036A (is") 1964-09-22

Similar Documents

Publication Publication Date Title
US3947937A (en) Control groove in cutting elements for metal working tools
US3875631A (en) Inserts for metal cutters
US4752186A (en) Coolable wall configuration
US6196771B1 (en) Face-milling method and apparatus
EP0225052B1 (en) Contoured tool blades
US3751782A (en) Throw away tips for metal cutting tools
JP2014210335A (ja) 冠歯車のワークピース上にギヤ歯をパワースカイビングするためのパワースカイビングツール
US3247766A (en) Process for machining tubular elements with fins for heat exchangers
DE1946826C3 (de) Läufer einer Axialströmungsmaschine
US4561809A (en) Cutting tool insert with chip breaker
EP3708283B1 (en) A cutting tool, a method for manufacturing a cutting tool and a method for machining of a workpiece
US3212992A (en) Nuclear fuel element casing
EP0389221B1 (en) Production method of honeycomb die-forming electrical discharge machining electrodes and production method of honeycomb dies
US3217382A (en) High speed rotary file
US4890454A (en) Wall surface structure having an improved radiant heat discharge capability
CN114029546B (zh) 一种细长管多头内螺旋槽拉刀
US3810286A (en) Methods for manufacturing hollow members
US2161901A (en) Broach
US3697192A (en) Hollow turbine blade
US3566494A (en) Broaching tool insert
US3231477A (en) Finned nuclear reactor fuel element
US3786719A (en) Hobbing cutter
US3678802A (en) Arrangement of cooling chambers for rocket engine combustion chambers
JP6182348B2 (ja) 切り屑除去機械加工用の刃先割出し可能な切削インサートおよび工具、ならびに工具用本体
US3279751A (en) Shrouded turbine or compressor blade