A stator for a downhole motor configured for use in a downhole environment. includes an inner tubular member formed from a first metallic material having an outer surface and a helically lobed inner surface, and an outer tubular member comprising a second metallic material that is different from the first metallic material. The inner tubular member is connected to the outer tubular member by compressive force passing from the outer tubular member through the inner tubular member to a rigid mandrel removably disposed within the inner tubular member. The inner tubular member and the outer tubular member form the stator of the downhole motor.

A stator for a downhole motor configured for use in a downhole environment. includes an inner tubular member formed from a first metallic material having an outer surface and a helically lobed inner surface, and an outer tubular member comprising a second metallic material that is different from the first metallic material. The inner tubular member is connected to the outer tubular member by compressive force passing from the outer tubular member through the inner tubular member to a rigid mandrel removably disposed within the inner tubular member. The inner tubular member and the outer tubular member form the stator of the downhole motor.

A method of making a stator includes positioning an inner tubular member having an inner surface within an outer tubular member, installing a rigid mandrel within the inner tubular member, and applying a compressive force to at least one of the inner tubular member and the outer tubular member.

A screw pump for transporting a fluid, with a drive spindle having a drive spindle profile and with at least one running spindle having a running spindle profile, the running spindle engages with its running spindle profile at least partially in the drive spindle profile of the drive spindle, the drive spindle profile and/or the running spindle profile is formed as a rolled profile, and a method for producing a spindle for such a screw pump, and a method for producing a groove in such a spindle are disclosed.

A method of making a stator includes positioning an inner tubular member having an inner surface within an outer tubular member, installing a rigid mandrel within the inner tubular member, and applying a compressive force to at least one of the inner tubular member and the outer tubular member.

A method for producing a pendulum of a pendulum slide cell pump may include providing a prefabricated pendulum body and performing a post-machining operation on the pendulum body only at a plurality of contact locations at which the pendulum body contacts at least one of an inner rotor and an outer rotor of the pendulum slide cell pump.

A screw pump for transporting a fluid, with a drive spindle having a drive spindle profile and with at least one running spindle having a running spindle profile, the running spindle engages with its running spindle profile at least partially in the drive spindle profile of the drive spindle, the drive spindle profile and/or the running spindle profile is formed as a rolled profile, and a method for producing a spindle for such a screw pump, and a method for producing a groove in such a spindle are disclosed.