Thread Turning Technical Data. Threading. Technical Data

Transcription

1 Thread Turning

2 THRAED TURNING TECHNICAL DATA Contents Thread Terminology achining a ulti-start Thread Insert Profile Styles Thread Turning ethods Thread Infeed ethods Calculating the Helix Angle and Choosing the Right Anvil Anvils and Anvil Kits Grades and their Applications Recommended Grades and Cutting Speeds - (not include ini and icro) Recommended Grades and Cutting Speeds - (ini and icro) Number of Passes Page 9 Page 0 Page 0 Page Page Page Page Page Page Page Page Cutting Conditions Depends on... Number of Passes and Depth of Cut per Pass for ulti Tooth Inserts Step by Step Thread Turning - Examples Troubleshooting Page Pages -9 Page 0- Page

3 Thread Terminology External Thread A thread on the external surface of a cylinder screw or cone Depth of Thread The distance between crest and root measured normal to the axis. Pitch Root Crest Pitch External Thread ajor Ø Pitch Ø inor Ø Thread Angle Helix Angle ajor Diameter The largest diameter of a screw thread. Pitch Diameter On a straight thread, the diameter of an imaginary cylinder, the surface of which cuts the thread forms where the width of the thread and groove are equal. inor Diameter The smallest diameter of a screw thread. The distance between corresponding points on adjacent thread forms measured parallel to the axis. This distance can be defined in millimeters or by the tpi (threads per inch), which is the reciprocal of the pitch. Helix Angle For a straight thread, where the lead of the thread and the pitch diameter circle circumference form a right angled triangle, the helix angle is the angle opposite the lead. Straight Thread Nominal Diameter The diameter from which the diameter limits are derived by the application of deviation allowances and tolerances. Internal Thread A thread on the internal surface of a cylinder or cone. A thread formed on a cylinder Taper Thread A thread formed on a cone Left-hand thread Right-hand thread A thread which, when viewed axially, winds in a counterclockwise and receding direction. All left-hand threads are designated LH. A thread which, when viewed axially, winds in a clockwise and receding direction. Threads are always righthand unless otherwise specified. The Helix Angle b Helix Angle Lead π x Pitch Diameter Lead The distance a threaded part moves axially, with respect to a fixed mating part, in one complete revolution. The lead is equal to the pitch multiplied by the number of thread starts. 9

4 achining a ulti-start Thread A thread in which the lead is an integral multiple, greater than one, of the pitch. A multistart thread permits a more rapid advance without a coarser (larger) thread form. First Start achined Second Start achined Third Start achined (Final, Starts Thread) Pitch Pitch Lead Pitch Lead Lead = x Pitch Insert Profile Styles Partial Profile Full Profile The V partial profile insert cuts without topping the outer diameter of the thread. The same insert can be used for a range of different thread pitches which have a common thread angle. Full Profile for Fine Pitches The full profile insert will form a complete thread profile including the crest. For every thread pitch and standard, a separate insert is required. Semi Full The full profile for Fine Pitches will form a complete thread. The topping of the outer diameter is generated by second tooth. The Semi profile insert will form a complete thread including crest radius but without topping the outer diameter. ainly used for trapezoidal profiles. 0

5 Thread Turning ethods Thread Inserts & Toolholder Rotation Feed Direction Helix ethod Drawing No. Right Hand External Right Hand Internal Left Hand External Left Hand Internal EX RH EX LH IN RH IN LH EX LH EX RH IN LH IN RH Anticlockwise Clockwise Anticlockwise Clockwise Clockwise Anticlockwise Clockwise Anticlockwise Towards chuck From chuck Towards chuck From chuck Towards chuck From chuck Towards chuck From chuck Regular Reversed Regular Reversed Regular Reversed Regular Reversed External RH Thread External LH Thread Internal RH Thread Internal LH Thread Thread Infead ethods Radial Infeed Flank Infeed (modified) Alternate Flank Infeed - Radial infeed is the simplest and quickest method. The feed is perpendicular to the turning axis, and both flanks of the insert perform the cutting operation. Radial infeed is recommended in cases: when the pitch is smaller than tpi for material with short chips for work with hardened material Flank infeed is recommended in the following cases: when the thread pitch is greater than tpi., using the radial method, the effective cutting edge length is too large, resulting in chatter. for TRAPEZ and ACE. The radial method result in three cutting edges, making chip flow very difficult. Use of the alternate flank method is recommended especially in large pitches and for materials with long cihps. This method divides the load equally on both flanks, resulting in equal wear along the cutting edges. Alternate flank infeed requires more complicated programming, and is not available on all lathes.

6 Calculating the Helix Angle and Choosing The Right Anvil Flank Clearance Angle a ' 0, UN, ISO ' ' ' ' ' 0 ACE BUTTRESS INSERT Vardex toolholders are designed to tilt the insert when seated in the toolholder (0 for external, for internal tooling). This results in the differing flank clearance angles, based on the geometry of insert. To ensure that the side of the insert cutting edge will not rub on the workpiece, it is most important that the insert helix angle be correct - especially in profiles with small enclosed flank angles. This correction is provided by Vardex anvils. A - A a f d A A a = arctan (tan Ø / x tand) Where: a - Flank clearance angle d - Tilt angle Ø - Enclosed flank angle Calculating the Helix Angle b b p The helix angle is calculated by the following formula: D b = arctan P xn xd b - Helix angle [ ] P - Pitch [mm] N - No. of starts D - Pitch diameter [mm] Lead = P x N The helix angle can also be found from the diagram below. Helix Angle Diagram Standard helix angle b Feed towards the chuck. Standard toolholder pocket angle Feed towards the tailstock Reversed helix angle -b. Standard toolholder pocket angle Anvil angle Anvil angle H H The dimension H (cutting edge height) remains constant with every insert/ anvil combination. Feed direction towards the chuck Feed direction towards the tailstock RH Thread/ RH Tooling LH Thread/ LH Tooling LH Thread/ RH Tooling RH Thread/ LH Tooling Pitch P* [mm] Special Toolholders Special Toolholders Pitch P* b = [tpi] b= 0 00 b = - *For ulti-start threads,use the lead value instead of the pitch Pitch diameter [mm] =0 b b=-

7 Anvils Resultant Helix Angle.º.º.º.º 0.º 0º -0.º -.º Insert Size Holder Ordering Code IC L mm /" /" /"U ER / IL ER / IL ER / IL YE-P YE-P YEU-P YE-P YE-P YEU-P YE-P YE-P YEU-P YE YE YEU YE-N YE-N YEU-N YE-.N YE-.N YEU-.N YE-N YE-N YEU-N YE-N YE-N YEU-N EL / IR EL / IR EL / IR YI-P YI-P YIU-P YI-P YI-P YIU-P YI-P YI-P YIU-P YI YI YIU YI-N YI-N YIU-N YI-.N YI-.N YIU-.N YI-N YI-N YIU-N YI-N YI-N YIU-N /" ER / IL EL / IR YE-P YI-P YE-P YI-P YE-P YI-P YE YI YE-N YI-N YE-.N YI-.N YE-N YI-N YE-N YI-N /"U ER / IL YEU-P YEU-P YEU-P YEU YEU-N YEU-.N YEU-N YEU-N EL / IR YIU-P YIU-P YIU-P YIU YIU-N YIU-.N YIU-N YIU-N /" ER / IL YE-P YE YE-N YE-.N YE-N EL / IR YI-P YI YI-N YI-.N /" ER / IL YE-P YE YE-N YE-.N YE-N EL / IR YI-P YI YI-N YI-.N /" ER / IL YE YE-N YE-.N EL / IR YI YI-N YI-.N /"Z ER / IL YEZ-P YEZ YEZ-N EL / IR YIZ-P YIZ YIZ-N /"Z ER / IL YEZ EL / IR YIZ /"T ER / IL EL / IR YT Standard Anvil U Style Anvil Style Anvil Z Style Anvil T Style Anvil ER/IL EL/IR ER/IL EL/IR ER/IL EL/IR ER/IL EL/IR ER/IL EL/IR Same anvil turned over Anvil Kits Anvil Size Ordering Code Included Anvils: IC L mm / ABY YE-P, P, N, N, N YI-P, P, N, N, N / ABY YE-P, P, N, N, N YI-P, P, N, N, N / U ABYU YEU-P, P, N, N, N YIU-P, P, N, N, N / ABYE ABYI YE-P, P, N, N, N YI-P, P, N, N, N / U ABYEU ABYIU YEU-P, P, N, N, N YIU-P, P, N, N, N To ensure that you always have on hand an assortment of anvils for any job, we recommend that anvil kits be readily available.

8 Grades and their Applications Grade Application Sample VTX First Choice grade for general use. A tough sub-micron substrate with TiAlN coating. Provides good fracture toughness and excellent wear resistance. VCB Vardex Sintered chipbreaker for general use. The combination of sintered chipbreaker with ground profile provides excellent chip control and high quality of thread. TiAlN coating. V Premium grade for stainless steel. Extra tough coating. Special multi-layer PVD coating guaranteeing higher resistance to wear in Stainless Steel application. VKX High hardness substrate for steels, stainless steel, non ferrous & aluminium. Recommended for rigid machine conditions. TiN coating. VSX For machining steels at low cutting speed. TiN coating. VK The uncoated grade for nonferrours, aluminium, high temperature and titanium alloys. VKP The uncoated grade for nonferrours, aluminium, high temperature and titanium alloys. VKP - with polished chipbreaker for high quality surface finish on aluminium. VKP General use carbide grade for ini inserts. TiN coated VHX General use HSS grade for ini inserts. For machining at low cutting speed. TiN coated VX General use carbide grade for icro inserts. TiN coated

9 Recommended Grades and Cutting Speeds Vc [m/min] (Not including ini & icro) aterial Unalloyed steel Low carbon (C=0.-0. %) edium carbon (C=0.-0. %) High carbon (C=0.-0. %) Low alloy steel Non hardened (alloying elements %) P High alloy steel Annealed (alloying elements > %) Low alloy (alloying elements <%) Cast steel High alloy (alloying elements >%) Stainless steel Non hardened Feritic Stainless steel Austenitic Austenitic Super austenitic Stainless steel Non hardened Cast feritic Stainless steel Austenitic Cast austenitic High temperature Annealed (Iron based) alloys Aged (Iron based) Annealed (Nickel or Cobalt based) Aged (Nickel or Cobalt based) Titanium alloys Pure 99. Ti a+b alloys Extra hard steel & tempered alleable Ferritic (short chips) cast iron Pearlitic (long chips) Grey cast iron Low tensile strength High tensile strength K Nodular SG iron Feritic Pearlitic Aluminium alloys non aging Wrought Aged Aluminium alloys Cast Cast & aged Aluminium alloys Cast Si -% Copper and Brass copper alloys Bronze and non leaded copper Hardness Brinell HB Rm 00Rm HRc First choice VTX VCB Vc[m/min] Coated V VKX VSX Uncoated VK / VKP Calculation of N [RP] N = 000 x V c p x D Vc = N x p x D 000 N D Vc N - Revolution Per inute [RP] V c - Cutting Speed [m/min] D - Workpiece Diameter [mm]

10 Recommended Grades and Cutting Speeds Vc [m/min] ini and icro aterial Unalloyed steel Low carbon (C=0.-0. %) edium carbon (C=0.-0. %) High Carbon (C=0.-0. %) Low alloy steel Non hardened P (alloying elements %) High alloy steel Annealed (alloying elements > %) Low alloy (alloying elements <%) Cast steel High alloy (alloying elements >%) Stainless steel Non hardened Feritic Stainless steel Austenitic Austenitic Super austenitic Stainless steel Non hardened Cast feritic Stainless steel Austenitic Cast austenitic High temperature Annealed (Iron based) alloys Aged (Iron based) Annealed (Nickel or Cobalt based) Aged (Nickel or Cobalt based) Titanium alloys Pure 99. Ti a+b alloys Extra hard steel & tempered alleable Ferritic (short chips) cast iron Pearlitic (long chips) Grey cast iron Low tensile strength High tensile strength Feritic Nodular SG iron Pearlitic K Aluminium alloys non aging Wrought Aged Aluminium alloys Cast Cast & aged Aluminium alloys Cast Si -% Copper and Brass copper alloys Bronze and non leaded copper Hardness Brinell HB Rm 00Rm HRc VX icro Inserts Vc[m/min] Coated VKP ini Inserts VHX ini Inserts

11 Number of Passes Pitch mm tpi No. of passes No. of passes (SCB) No. of passes (icro&ini) Cutting Conditions Depends on: aterial Type Workpiece aterial Dimension: Diameter and Length L D Chipflow Character aterial Hardness HRc HB Thread Application External or Internal Profile Shape Surface Finish achine Stability achine ax. RP RP N Clamping System Stability Coolant Coolant Type Holder Cross Section Area Holders Holder Overhang Through Coolant Option Overhang Shank Type: Carbide, Alloy, Carbide Implant Grade P K Insert Profile Shape: Pitch and Depth Nose Radius Chipbreaker Style R

12 Number of Passes and Depth of Cut per Pass for ulti Tooth Inserts Standard Insert Type Insert Size Pitch Teeth Ordering Code Passes Depth of cut per pass IC L mm RH ISO External.0 mm ER.0ISO /". mm ER.ISO T /" /" /"T. mm.0 mm.0 mm.0 mm. mm.0 mm.0 mm ER.ISO... ER.0ISO... ER.0ISO... ER.0ISO... ER.ISOT... ER.0ISOT... ER.0ISOT ISO Internal /".0 mm IR.0ISO /". mm. mm.0 mm IR.ISO... IR.ISO... IR.0ISO T /" /"T.0 mm.0 mm. mm.0 mm.0 mm IR.0ISO... IR.0ISO... IR.ISOT... IR.0ISOT... IR.0ISOT UN External /" /" tpi tpi tpi tpi ERUN... ERUN... ERUN... ERUN Z /" /" ERUN... ERUNZ UN Internal /" /" tpi tpi tpi tpi IRUN... IRUN... IRUN... IRUN Z /" /" IRUN... IRUNZ BSW External /" tpi ERW /" tpi ERW tpi ERW BSW Internal /" tpi IRW /" tpi IRW tpi IRW Style Insert T Style Insert Z Style Insert

13 Number of Passes and Depth of Cut per Pass for ulti Tooth Inserts (con t) Standard Insert Type Insert Size Pitch Teeth Ordering Code Passes Depth of cut per pass IC L mm RH NPT External NPT Internal NPTF External NPTF Internal APIBUT External APIBUT Internal APIRD External APIRD Internal /" /" Z /" T /"T /" /" Z /" T /"T /" /" /" /" /" /" /" Z /" T /"T /" /" Z /" T /"T. tpi. tpi. tpi. tpi. tpi. tpi. tpi. tpi. tpi. tpi. tpi tpi tpi 0 tpi 0 tpi 0 tpi 0 tpi 0 tpi 0 tpi 0 tpi 0 tpi ER.NPT... ER.NPT... ERNPT... ER.NPTZ... ERNPTZ... ER.NPTT... ERNPTT... IR.NPT... IR.NPT... IRNPT... IR.NPTZ... IRNPTZ... IR.NPTT... IRNPTT... ER.NPTF... IR.NPTF... IR.NPTF... ERBUTT... IRBUTT... ER0APIRD... ER0APIRD... ERAPIRD... ERAPIRDZ... ERAPIRDZ... ER0APIRDT... ERAPIRDT... ERAPIRDT... IR0APIRD... IR0APIRD... IRAPIRD... IR0APIRDZ... IRAPIRDZ... IR0APIRDT... IRAPIRDT... ERAPIRDT

14 Y Step by Step Thread Turning - Example 0 x. Application: Thread: External Right Hand ISO etric 0x. aterial: 0 ( HRc) Choose the Thread Turning ethod (see page ) Feed direction towards the chuck was chosen. Therefore an external right hand insert and an external right hand holder will be used. Choose the Insert Size (see page ) X L IC Chosen insert: ER.ISO Insert Size IC L mm Pitch mm Ordering Code RH Anvil RH Toolholder /. ER.ISO... YE AL..-(LH) Choose the Toolholder (see page 9) H H F L L B Chosen toolholder: AL - Insert Size IC Ordering Code RH / AL - Dimensions mm H=H=B F L L. 0 Determine the Helix Angle (see page ) Pitch P* [mm] Special Toolholders 0 Pitch P* b = [tpi] b = D =0 b 0 00 Pitch diameter [mm] From the table, using a pitch of. mm (0 tpi) and a workpiece diameter of 0 mm (. ), we find the helix angle to be..

15 Choose the Correct Anvil (see page ) Anvil chosen: YE Resultant Helix Angle Insert Size Holder Ordering Code IC L mm / ER/IL YE-P YE-P YE YE-N Choose the Carbide Grade and Cutting Speed (see page ) Carbide grade chosen: VTX Cutting speed: 0 m /min P aterial: Low alloy steel (alloying elements %) Non hardened Hardness Brinell HB 0 0 First choice VTX VCB Determine the Number of Passes Number of passes: 0 ISO External (see page ) Pitch mm tpi 0 No. of passes Summary Thread Type Feed Direction: Insert and Grade: Toolholder: Helix Angle: Anvil Cutting Speed: Number of Passes: ISO 0x. External Right Hand Towards the chuck ER.ISO VTX AL -. YE 0 m/min 0

16 X Step by Step Thread Turning - Example -ACE-G Application: Thread: Internal Right Hand ACE Pitch: tpi Bore dia: aterial: Stainless Steel Austemitic Choose the Thread Turning ethod (see page ) To facilitate the removal of chips from the machined area, we chose a feed direction away from the chuck. Therefore an internal left hand insert and an internal left hand toolholder are to be used. Choose the Insert Size (see page 9) Y L IC Chosen insert: ILACE Insert Size Pitch Ordering Code IC L mm tpi RH Anvil LH / ILACE... YE Toolholder AVR..-(LH) Choose the Toolholder (see page 0) D F L L D A Chosen toolholder: AVR 0-LH Insert Size Ordering Code Dimensions mm in Bore IC RH A L L D D F mm / AVR Determine the Helix Angle (see page ) Pitch [mm] Special Toolholders 0 00 b = - Pitch diameter [mm] 0 00 D =0 b b=- In this case, a right hand thread is being turned with a left hand toolholder. The reverse helix method is used. From the lower part of the table, using a pitch of tpi and a bore diameter of mm, we obtain a helix angle of -0..

17 Choose the Correct Anvil (see page ) Anvil chosen: YE-N Resultant Helix Angle Insert Size IC L mm / Ordering Code ER/IL YE YE-N YE-.N YE-N YE-N Choose the Carbide Grade and Cutting Speed (see page ) Carbide grade chosen: VTX Cutting speed: 0 m /min aterial: Stainless steel Austenitic Austenitic Super austenitic Hardness Brinell HB 0 00 First choice VTX VCB Determine the Number of Passes (see page ) Number of passes: ACE External & Internal Pitch mm tpi.. No. of passes Summary Thread Type Feed Direction: Insert and Grade: Toolholder: Helix Angle: Anvil Cutting Speed: Number of Passes: American ACE Internal Right Hand Away from the chuck ILACE VTX AVR 0-LH -0. YE-N 0 m/min

18 Troubleshooting Problem Possible Cause Solution Increased flank wear Cutting speed too high Depth of cut too low/ too many passes Unsuitable carbide grade Insufficient cooling Reduce cutting speed/ use coated insert Increase the depth of cut per pass Use a coated carbide grade Increase coolant flow rate Uneven cutting edge wear Incorrect helix angle Wrong infeed method Choose the correct anvil Use the Alternating Flank Infeed method Depth of cut too large Extreme Insufficient cooling plastic Cutting speed too high deformation Unsuitable carbide grade Nose radius too small Decrease depth of cut/ increase number of passes Increase coolant flow rate Reduce cutting speed Use a tougher carbide Use an insert with a larger radius, if possible Cutting edge breakage Depth of cut too large Extreme plastic deformation Insufficient cooling Unsuitable carbide grade Instability Decrease depth of cut/ increase number of passes Use a tougher carbide Increase flow rate and/ or correct flow direction Use a tougher carbide Check stability of the system Built-up edge Incorrect cutting speed Unsuitable carbide grade Change the cutting speed Use a coated carbide Thread profile is too shallow The tool is not at the workpiece axis height Insert is not machining the thread crest Worn insert Change tool height easure the workpiece diameter Change the cutting edge sooner Poor surface quality Cutting speed too low Wrong anvil Flank infeed method is not appropriate Increase cutting speed Choose correct anvil Use the alternate flank or radial infeed method