JPH0347940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a heat generating tube of a sheathed glow plug.

[Prior Art] Conventionally, the swaging process of the heat generating tube 100 is performed by attaching the combined body 110 to the cover of the combined body 110 in the processing section of the swaging machine 1, as shown in FIG. 5 (see FIGS. 1 to 4). A cylindrical workpiece holder having an adaxial center at the rear end side of a center electrode rod 103 protruding from a heat-resistant metal pipe 102 provided at the tip of a moving mechanism (not shown) of a processing motor (workpiece).
1A, insert it from the tip side of the pipe 102 between a pair of dies 2 arranged at the center of the processing section 10, perform swaging processing, and sequentially move the holder 1A to the right in the figure to open the pipe 102. After swaging the side and narrowing the entire length of the pipe 102, return the holder 1A to the position where the workpiece on the left side of the figure was attached and remove the swaged heat generating tube 100 from the holder 1A. ,
Alternatively, as shown in FIG. 5, move the holder 1A further to the right in the figure to remove the heated tube 100 after processing.
It was done by pushing down.

[Problem to be solved by the invention] However, in the case of this conventional processing method,
Electrically insulating ceramic powder 10 in pipe 102
7 moves from the closed end to the open end, so the tip (closed end)
As the packing density decreases at the side, especially at the welded part of the heating coil 104, the holding force of the heating coil 104 becomes insufficient, making wire breakage due to vibration more likely to occur, and thermal conductivity also decreases.
04 was oxidized by the internal air, resulting in a loss of durability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a heat generating tube of a sheathed glow plug in which electrically insulating ceramic powder can be densely packed on the side of the distal end of the heat generating tube.

[Means for Solving the Problems] In order to achieve the above object, the present invention connects one end of a heating coil through an opening at the rear end of a heat-resistant metal pipe whose tip is narrowed to a small diameter and has a hole. A metal center electrode rod fixed to the tip is concentrically inserted, the other end of the heating coil is fixed to the tip side of the heat-resistant metal pipe, the hole is closed, and the pipe is filled with electrically insulating ceramic powder. At the same time, a configuration was adopted in which an elastic stopper was attached to the opening, and this was swaged from the rear end side to reduce the outside diameter of the pipe to a set dimension.

[Actions and Effects of the Invention] The method for manufacturing a heat generating tube of a sheathed glow plug according to the present invention has the following effects due to the above configuration.

(a) Since the swaging process is performed from the rear end of the heat-resistant metal pipe, the electrically insulating ceramic powder filled inside has a high packing density at the tip, increasing the holding power of the heating coil.

(b) By increasing the holding power of the heating coil by the electrically insulating ceramic powder, disconnection of the heating coil due to vibration can be prevented.

(c) Because the packing density of electrically insulating ceramic powder around the heating coil is high, the heat generated by the heating coil is efficiently transferred into the heating tube, and the surface temperature of the heating tube rises quickly, causing the temperature to rise rapidly from the tip. It becomes red hot and can improve starting performance.

(d) By increasing the density of the electrically insulating ceramic powder, there is less air inside, which prevents oxidation of the heating coil and improves its durability, making it more reliable as a glow plug. It has a remarkable effect compared to edge processing.

[Example] Next, the present invention will be described with reference to FIGS. 1 to 4 and 6.
This will be explained based on the embodiment shown in FIGS.

The heat generating tube 100 is manufactured by using a pipe 102 made of a heat-resistant metal such as stainless steel, the tip of which is narrowed to a slightly smaller diameter to form a tip hole 101, as shown in FIG.
A heating coil 10 is attached to the tip of the metal center electrode rod 103.
A welded body 106 is manufactured by fixing a heat-resistant metal plug 105 to the other end of the pipe 102 by welding or the like.
The welded body 106 is inserted inside.

Next, the plug 105 is inserted into the tip hole 10 as shown in FIG.
1 is fitted and welded, and an electrically insulating ceramic powder 10 such as magnesia is placed inside the pipe 102.
7, and a stopper 108 made of an elastic material such as rubber is inserted into the opening.
A combined body 110 is manufactured by fitting the two.

Furthermore, this combined body 110 is swaged and narrowed by the outer diameter of the pipe 102 using a swaging machine, so that the tip side of the center electrode rod 103 is concentrically placed inside the metal tube bottom 109 with a closed tip as shown in FIG. The metal tube bottom 109 and the tip of the center electrode rod 103 are connected by a heating coil 104, and the metal tube is filled with electrically insulating ceramic powder 107 and a glass seal 121 is applied to the open end. A heat generating tube 100 is manufactured.

As shown in FIG. 4, this heating tube 100 is coaxially fitted into a mounting bracket 120, and the tip of the mounting bracket 120 and the rear end of the metal tube bottom 109 are fixed by brazing or the like. Further, other necessary parts such as the terminal 130 are assembled to form the sheathed glow plug 140.

FIG. 6 shows a swaging machine used for swaging the heat generating tube 100 of the sheathed glow plug 140. The swaging machine includes a base (bed) 20, a swaging section 10 provided at the center of the bed 20, a motor M mounted below the swaging section 10, and a swaging section 10 mounted on the bed 20. A workpiece moving mechanism 30 is mounted on both sides of the swaging section 10 so as to be coaxial with the main axis of the swaging section 10.

The swaging processing section 10 has a known configuration, and includes a cylindrical or disc-shaped case 11 that is fastened to the upper surface of the bed 20 so that its axis is horizontal.
an inside ring 12 fitted to the inner periphery of the case 11; and an input pulley 15 arranged on the side of the case 11 and connected to a drive pulley 13 provided on the output shaft of the motor M via a belt 14. and a large number (eight in this embodiment) of hammer rollers arranged at equal intervals on the inner circumference of the inside ring 12, connected to the input pulley 15, and rotating while rotating along the inner circumference of the inside ring 12. (outer peripheral roller) 16, a pair of hammers (hammers) 17 and a pair of spindles 18, which are alternately arranged opposite to each other inside the rotational orbit of the hammer roller 16;
A wedge 19 is inserted inside the buckler 17 so as to be displaceable in the axial direction, and a pair of dies 2 are arranged inside the wedge 19 and have an inner diameter adjusted by the axial position of the wedge 19. Become. Work guide tubes 21 and 22 are provided on both sides of the die 2 and are concentric with the main axis, which is the center of the center grooves 2A and 2B of the die 2, and into which the arbor is inserted, respectively.

The workpiece moving mechanism 30 is provided on one side (left side in the figure) of the swaging processing section 10, and includes a pushing arbor 3 that is reciprocated by an air cylinder 31.
2, and a receiving arbor 34 which is provided on the other side (right side in the figure) of the swaging processing section 10 and is reciprocated by an air cylinder 33.

This swaging machine generates heat tube 1
In the swaging process of 00, the combined body 110 shown in FIG. 2 is held between the tip of the pusher arbor 32 and the receiver arbor 34 by one pressing force, and this is inserted into the pipe as shown in FIG. The pipe 102 is swaged using a die from the opening side of the pipe 102.
Once the entire length of the workpiece has been reduced to a predetermined outer diameter, the arbors 32 and 34 are returned, or they are further advanced and the workpiece is dropped at a predetermined position.

10 and 11 show other embodiments.

In this embodiment, instead of holding the workpiece between a pair of arbors in the workpiece moving mechanism, checks 41 and 42 are provided on both sides of the die, and the workpiece is changed over to perform swaging processing over the entire length of the pipe 102. I have to.

[Brief explanation of drawings]

1, 2, 3, and 4 are process diagrams for manufacturing a sheathed glow plug. FIG. 5 is a swaging process diagram of a conventional heat generating tube. FIG. 6 is a front view of a swaging machine used in the method of manufacturing a heat generating tube for a sheathed glow plug according to the present invention, FIG. 7 is an enlarged sectional view of the swaging machine, and FIG. 8 is a side view thereof. FIG. 9 is an explanatory diagram of its operation. FIGS. 10 and 11 are schematic diagrams of other embodiments. In the figure, 100... Heat generating tube, 102... Heat resistant metal pipe, 103... Center electrode rod (metal center electrode rod), 104... Heat generating coil, 107...
... Electrically insulating ceramic powder, 108 ... Elastic plug, 140 ... Seeded glow plug.

Claims (1)

[Scope of Claims] 1. A metal center electrode rod with one end of a heating coil fixed to the tip is concentrically connected through an opening at the rear end of a heat-resistant metal pipe whose tip is narrowed to a small diameter and has a hole. the other end of the heating coil is fixed to the tip side of a heat-resistant metal pipe and the hole is plugged, the pipe is filled with electrically insulating ceramic powder and an elastic stopper is attached to the opening; A method of manufacturing a heat generating tube for a sheathed glow plug, in which the tube is swaged from the rear end to reduce the outside diameter of the pipe to the set dimensions.