Commutator having a plurality of commutator segments and method for making the same
A commutator has a plurality of commutator segments fixed to an insulating support member. The commutator segments are formed by cold or hot forming a copper billet cut from a length of copper wire. Each billet has a volume approximately equal to the volume of one commutator segment. Each commutator segment has a main body and an anchor integrally formed with the main body. The commutator segments are spaced about a circle and then an insulating support member is molded to the commutator segments to fix the commutator segments to the support member.
1. A method of making a commutator having a plurality of commutator segments fixed to an insulating support member, the method comprising the steps of:
providing a plurality of copper billets;
providing a cold heading treatment to each copper billet to form a cold headed copper billet, each cold headed copper billet having a first portion at one axial end and a second portion at the other axial end, the first portion has a diameter smaller than the second portion;
pressing each cold headed copper billet into a commutator segment having a main body and at least one anchor integrally formed with the main body;
soldering the commutator segments to a conductive ring so that the commutator segments are spaced about a circle;
molding an insulating support member to the arranged commutator segments to fix the commutator segments to the support member; and
dividing the conductive ring into a plurality of graphite sectors, each graphite sector being fixed with one corresponding commutator segment.
2. The method of claim 1 , wherein the step of pressing each copper billet includes performing a cold forming treatment.
3. The method of claim 2 , the cold forming treatment comprises performing cold heading and/or cold forging.
4. The method of claim 1 , wherein the pressing step includes performing a hot forming treatment.
5. The method of claim 1 , wherein the pressing step includes forming a projection as the anchor on one surface of the main body.
6. The method of claim 5 , wherein the pressing step further comprises splitting the projection to form the anchor into a V-shaped projection.
7. The method of claim 5 , wherein the pressing step further comprises forming the projection inclined to the main body.
8. The method of claim 1 , further comprising bending one end of the main body corresponding to the first portion to form a tang.
9. The method of claim 1 , wherein the step of providing a plurality of copper billets includes cutting the copper billets from a length of copper wire.
10. The method of claim 1 , wherein the step of soldering the commutator segments to a conductive ring comprises forming a first space in the circumferential direction between main bodies of adjacent commutator segments; the step of dividing the conductive ring into a plurality of sectors comprises forming a second space in the circumferential direction between adjacent sectors, the second space is smaller than the first space.
11. The method of claim 1 , wherein the step of soldering the commutator segments to a conductive ring comprises forming a space having an uneven width along a radial direction of the commutator in the circumferential direction between main bodies of adjacent commutator segments.
12. The method of claim 11 , wherein the step of soldering the commutator segments to a conductive ring further comprises forming the width of the middle of the space to be smaller than that of the radial outer end of the space.
13. A method of making a commutator having a plurality of commutator segments fixed to an insulating support member, the method comprising the steps of:
providing a plurality of copper billets;
providing a cold heading treatment to each copper billet to form a cold headed copper billet, each cold headed copper billet having a first portion at one axial end and a second portion at the other axial end, the first portion has a diameter smaller than the second portion;
pressing each cold headed copper billet into a commutator segment having a main body and at least one anchor integrally formed with the main body, the main body having a narrower portion formed by the first portion and a wider portion formed by the second portion; and
molding an insulating support member to the arranged commutator segments to fix the commutator segments to the support member.
14. The method of claim 13 , wherein the step of providing a plurality of copper billets comprises a step of providing a cylindrical copper rod or copper wire, and a step of cutting the copper rod or copper wire into a plurality of individual copper billets.