JP2898732B2 - Manufacturing method of magnetic scale - Google Patents

Description

The present invention relates to a method for manufacturing a magnetic scale for detecting a stroke position of a hydraulic cylinder or the like, for example.

(Prior art) In order to detect the stroke position of a hydraulic cylinder, etc.,
A band-shaped non-magnetic portion is provided at equal intervals on the piston rod to form a magnetic scale, and a magnetic sensor installed on the cylinder side can detect a pulse signal corresponding to the piston stroke, for example, feedback control of the operation of the hydraulic cylinder And so on.

In this case, as shown in FIGS. 3 and 4, the magnetic scale formed on the piston rod is equally spaced in the axial direction by machining or etching on the surface of the piston rod 1 made of iron or the like. A non-magnetic portion is formed by plating a non-magnetic material 3 such as chrome on the band-shaped groove 2 and back-filling the band-shaped groove 2.

(Problems to be Solved by the Invention) However, there are the following problems when manufacturing a magnetic scale in this way.

In other words, it takes a long time to process the chrome plating required to fill the processed groove with a non-magnetic material. Therefore, the thickness of the non-magnetic portion is limited in terms of processing and cost. The output could not be increased.

An object of the present invention is to solve such a problem and to provide a method for efficiently and accurately manufacturing a magnetic scale in a short time.

(Means for Solving the Problems) Accordingly, the present invention is a method for manufacturing a magnetic scale in which band-shaped non-magnetic portions are arranged at predetermined intervals on a base material formed of a magnetic material, the method comprising: Grooves are formed at predetermined intervals, metal powder such as stainless steel or a wire is supplied to the grooves, and high-density thermal energy including a laser beam is applied to the grooves to melt and build up, thereby forming a non-austenitic non-metal layer. A magnetic part was formed.

(Operation) When a metal powder such as stainless steel or a wire is supplied to the groove portion and a laser beam or the like is applied to the groove, nickel or chrome contained in the metal powder or the wire is melted and diffused, and the metal structure is non-magnetic. Since a certain austenite phase is formed, a sufficiently thick nonmagnetic portion can be efficiently formed.

(Example) An example of the method of the present invention will be described with reference to the drawings.

As shown in FIG. 1 and FIG.
(In this embodiment, a piston rod, the same applies hereinafter) is formed of an iron-based magnetic material, and grooves 10a are formed in the piston rod 10 at equal intervals.

The metal powder such as stainless steel is supplied to the groove 10a from the nozzle 11 while irradiating a carbon dioxide laser beam with the laser nozzle 12 while the metal powder is melted to build up the austenitic phase 13 which is a nonmagnetic material. To form

Nickel and chrome contained in metal powder such as stainless steel are melted and diffused by irradiation with a carbon dioxide gas laser beam, and constitute an austenitic phase 13 which is a nonmagnetic material in terms of metallographic structure.

In order to form a magnetic scale at equal intervals in the axial direction on the surface of the piston rod 10, the piston rod 10 is rotated while irradiating a laser beam together with the supply of metal powder such as stainless steel to melt a predetermined length. Groove 10a in the axial direction
The operation of moving the piston rod 10 by a predetermined angle while rotating the piston rod 10 by one pitch while irradiating the laser beam while supplying the metal powder again is repeated.

In this way, for example, 0.2 mm
A non-magnetic portion having a thickness of 0.5 mm is formed.

FIG. 2 shows a processing apparatus for this purpose. A slide table 21 is slidably mounted on a slide base 20,
The slide table 21 is fed in the axial direction according to the rotation of the motor 22. The slide table 21 is provided with a pair of supports 23a and 23b that rotatably support the piston rod 10 so that the slide table 21 has a rotation axis that matches the feed direction, and the support table 23a rotates the piston rod 10. A motor 25 is provided for driving the motor.

A laser nozzle 12 for irradiating a carbon dioxide laser beam is provided above the piston rod 10 supported by the support bases 23a and 23b, and the laser nozzle 12 receives a laser beam generated by a laser beam oscillator 26. Sent. The laser nozzle 12 focuses the laser beam on the groove surface of the piston rod 10 by a lens.

A nozzle 11 for supplying a metal powder such as stainless steel is provided near the laser nozzle 12, and a hopper 27 for storing the metal powder is connected to the nozzle 11, and a gas introduction pipe 28 is provided.
The metal powder is supplied from the nozzle 11 to the surface of the base material by the argon gas sent from the nozzle.

Supply metal powder from nozzle 11 and laser nozzle 12
While the laser beam is being irradiated from above, the piston rod 10 is rotated by a predetermined angle at a predetermined speed by a motor 25, and the metal powder is melted and built up in the groove 10a to form a band-shaped non-magnetic portion. Next, the motor 25 is returned to the original angular position, and the slide table 21 is fed by rotating the motor 22 by an amount corresponding to the pitch of the magnetic scale.
In this state, the piston rod 10 is rotated while supplying the metal powder again from the nozzle 11 and irradiating the laser beam from the laser nozzle 12. The argon gas (inert gas) spouted from the nozzle 11 prevents oxidation of the metal powder, and also emits an inert gas from the laser nozzle 12 at the same time as the laser beam for protecting optical components.

In this way, a magnetic scale can be formed on the surface of the piston rod 10 over a predetermined range. Specifically, when an iron piston rod with a diameter of 40 mm was rotated at a peripheral speed of 10 mm / sec, and a stainless steel powder was supplied together with argon gas at a rate of 10 g / min, a carbon dioxide laser with an output of 800 W was irradiated. The lens width is adjusted to 1mm by increasing the distance between the lens and the focal point), depth 0.2
A non-magnetic portion of 5 mm was formed.

Thereafter, the surface of the piston rod 10 is polished and, if necessary, subjected to a chrome plating process to perform a final finish.

In this embodiment, a carbon dioxide laser beam was irradiated,
As a heat source of high-density thermal energy, an electron beam or TIG can be used, and a wire of stainless steel or the like may be supplied instead of a metal powder of stainless steel or the like. The metal powder such as stainless steel, wire, or the like may be supplied simultaneously with the laser irradiation, or may be fixed in the groove 10a in advance.

(Effects of the Invention) As described above, according to the present invention, a metal powder such as stainless steel or a wire is supplied to the groove of the base material, and the cladding is performed while irradiating high density thermal energy such as a laser beam to the groove. Alone, a non-magnetic part consisting of an austenite phase can be formed, so that the production efficiency is much better than that of a conventional method requiring a long-time plating treatment, etc. Also, the scale sensitivity can be freely changed depending on the groove processing, the amount of metal powder, the heat input conditions, etc.Moreover, it is easy to make the build-up thickness uniform and there is no variation in composition, so the performance and quality as a magnetic scale There is also an effect that it can be stabilized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a working state of an embodiment of the method of the present invention,
FIG. 2 is a structural view showing the structure of a processing apparatus for carrying out the method of the present invention, FIG. 3 is a partially cutaway side view of a piston rod magnetic scale, and FIG. 4 is a longitudinal sectional view thereof. 10 ... Base material (piston rod), 11 ... Nozzle, 12 ...
Laser nozzle, 13 ... Austenitic phase.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 26/00-26/18

Claims (1)

(57) [Claims] 1. A method of manufacturing a magnetic scale in which band-shaped non-magnetic portions are arranged at predetermined intervals on a base material formed of a magnetic material, wherein grooves are formed at predetermined intervals on the surface of an iron-based base material, Supply metal powder or wire such as stainless steel to this groove,
A method for manufacturing a magnetic scale, comprising irradiating a high-density thermal energy including a laser beam and melting the same to form a nonmagnetic portion made of an austenite phase.