Provided is an electrical dust-collecting filter manufacturing method and an electrical dust-collecting filter. The method includes the steps of: preparing a frame body, a dust-collecting electrode, a discharge electrode, and a discharge frame; assembling the dust-collecting electrode into an assembly hole of the frame body; connecting the discharge frame to the frame body via an insulating member; and arranging the discharge electrode in an axial direction inside the dust-collecting electrode via the discharge frame and fixing the same. The dust-collecting electrode assembling step includes: temporarily elastically deforming the dust-collecting electrode in the radial direction and inserting the same into the assembly hole of the frame body; and pressurizing end parts of both ends of the dust collecting electrode, which protrude out of a plate member when fitted into the assembly hole, in the axial direction such that the end parts are compressed against the surface of the plate member.

A coil spring winding apparatus (1) comprises a stator and a rotor (10) which is supported on the stator so as to be rotatable about a rotation axis (13). The rotation axis (13) extends along a spring axis of a coil spring wound by the coil spring winding apparatus. At least one winding tool (21, 22) is supported on the rotor (10) so as to rotate about the rotation axis (13) of the rotor (10) upon rotation of the rotor (10). The at least one winding tool (21, 22) is configured to bend a wire (8) to form the coil spring upon rotation of the rotor (10). The at least one winding tool (21, 22) is adjustable relative to the rotor (10).

A coil spring winding apparatus (1) comprises a stator and a rotor (10) which is supported on the stator so as to be rotatable about a rotation axis (13). The rotation axis (13) extends along a spring axis of a coil spring wound by the coil spring winding apparatus. At least one winding tool (21, 22) is supported on the rotor (10) so as to rotate about the rotation axis (13) of the rotor (10) upon rotation of the rotor (10). The at least one winding tool (21, 22) is configured to bend a wire (8) to form the coil spring upon rotation of the rotor (10). The at least one winding tool (21, 22) is adjustable relative to the rotor (10).

The present invention refers to a spring forming device (1) comprising: a system (3) for feeding a wire (4) for forming a helical spring (2); a winding system (7) suitable for winding said wire (4) according to a helical configuration having a predefined diameter (D) extending along a helix development axis (A); one or more pitch tools (11, 13, 9), each suitable for acting on the wire (4) so that it takes on said cylindrical helix configuration with a predefined pitch (p); a system (15) for detecting the actual pitch of the spring forming in device (1) starting from said wire (4); means for detecting the amount (I) of the fed wire; a control unit configured for: determining the actual length (L.sub.eff) of the spring forming in the device starting from the actual amount of the fed wire (I) and actual pitch (p.sub.eff) detected for portions of the spring, already formed in the device; determining a reference length (L) as a function of said actual amount (I) of fed wire; determining an error between said reference length (L) and said actual length (L.sub.eff); generating a command signal such to vary, during the spring formation, the configuration of one of said one or more pitch tools (11, 13, 9) as a function of said error. Moreover, the present invention refers to a method for forming springs and a corresponding computer program.

The present invention refers to a spring forming device (1) comprising: a system (3) for feeding a wire (4) for forming a helical spring (2); a winding system (7) suitable for winding said wire (4) according to a helical configuration having a predefined diameter (D) extending along a helix development axis (A); one or more pitch tools (11, 13, 9), each suitable for acting on the wire (4) so that it takes on said cylindrical helix configuration with a predefined pitch (p); a system (15) for detecting the actual pitch of the spring forming in device (1) starting from said wire (4); means for detecting the amount (I) of the fed wire; a control unit configured for: determining the actual length (L.sub.eff) of the spring forming in the device starting from the actual amount of the fed wire (I) and actual pitch (p.sub.eff) detected for portions of the spring, already formed in the device; determining a reference length (L) as a function of said actual amount (I) of fed wire; determining an error between said reference length (L) and said actual length (L.sub.eff); generating a command signal such to vary, during the spring formation, the configuration of one of said one or more pitch tools (11, 13, 9) as a function of said error. Moreover, the present invention refers to a method for forming springs and a corresponding computer program.

This coil spring has a part of high hardness and a part of lower hardness than the part. Also, it is preferable that the hardness of the part that comes into contact with other members is lower than the hardness of the part other than the part that comes into contact with the other members. Moreover, it is preferable that the hardness of an end turn part of the coil spring is lower than the hardness of the part other than the end turn part. Furthermore, it is preferable that the hardness of the part that comes into contact with a receiving member adapted to receive the end turn part of the coil spring is lower than the hardness of the part other than the part that comes into contact with the receiving member.

The invention relates to a method for manufacturing a coil spring and for determining a propelling condition for a shot medium. In a case where it is confirmed that the coating film remains in a third step, at least one or more of conditions of the shot peening treatment including a propelling speed of the shot medium, a propelling time of the shot medium, a material of the shot medium, and an average particle diameter of the shot medium are changed and the second step and the third step are repeated until the coating film does not remain. In a case where it is confirmed that the coating film does not remain in the third step, the condition of the shot peening treatment in the second step in which the coil spring is obtained with no remaining coating film is determined as the propelling condition for the shot medium.

The invention relates to a method for manufacturing a coil spring and for determining a propelling condition for a shot medium. In a case where it is confirmed that the coating film remains in a third step, at least one or more of conditions of the shot peening treatment including a propelling speed of the shot medium, a propelling time of the shot medium, a material of the shot medium, and an average particle diameter of the shot medium are changed and the second step and the third step are repeated until the coating film does not remain. In a case where it is confirmed that the coating film does not remain in the third step, the condition of the shot peening treatment in the second step in which the coil spring is obtained with no remaining coating film is determined as the propelling condition for the shot medium.

A spring forming device in which the steel wire can be continuously cut off without stopping the feeding of the steel wire in cutting, and in which the steel wire can be uniformly heated, is provided. The spring forming device has a wire supplying mechanism for supplying a steel wire using a plurality of feeding rollers, a heating mechanism for heating the steel wire, a coiling mechanism for forming in a coil state the heated steel wire, and a cutting mechanism for cutting the steel wire coiled at a given number of turns off the steel wire remained backward. A cutting blade of the cutting mechanism follows tracks having a speed Va that moves to the receiving blade and a speed Vc that moves in an axial direction of the coiled steel wire, in cutting of the steel wire.

A spring forming device in which the steel wire can be continuously cut off without stopping the feeding of the steel wire in cutting, and in which the steel wire can be uniformly heated, is provided. The spring forming device has a wire supplying mechanism for supplying a steel wire using a plurality of feeding rollers, a heating mechanism for heating the steel wire, a coiling mechanism for forming in a coil state the heated steel wire, and a cutting mechanism for cutting the steel wire coiled at a given number of turns off the steel wire remained backward. A cutting blade of the cutting mechanism follows tracks having a speed Va that moves to the receiving blade and a speed Vc that moves in an axial direction of the coiled steel wire, in cutting of the steel wire.