JPH0540884Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic drilling machine equipped with an automatic chip break mechanism that automatically discharges cutting chips generated during drilling operations.

[Background of the idea]

Magnetic drilling machines have become capable of cutting large diameter and deep holes by using a hole sorter type rotary cutting tool as cutting chips.

However, with conventional drills, the larger the diameter and the deeper the hole, the more chips are ejected, and the chips become entangled with the cutting edge, making removal of the chips extremely troublesome. In addition, problems such as a decrease in drilling efficiency and damage to the cutting tool occur due to clogging of chips, and the motor for driving the rotary tool becomes locked due to the entanglement of chips, and the magnet adhering to the workpiece comes off, causing the main body of the magnetic drilling machine to become damaged. I was in danger of being swung around and falling.

[Purpose of invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a magnetic drilling machine that smoothly removes chips, has good drilling efficiency, and has good operability.

[Summary of the idea]

This invention consists of a ball sleeve with opposing annular raceway surfaces, one of which is fixed to the spindle, and the other of which is pivoted so as to be slidable in the axial direction, and steel balls are held at regular intervals by a retainer. However, by providing a small amount of cam relief on the annular raceway surface, when the spindle rotates, a steel ball enters the cam relief and a chip break mechanism that moves the tip of the spindle in and out by a small amount can be built into the machine body. This is what I did.

[Example of idea]

The present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a magnetic drilling machine, and as is well known, a magnetic drilling machine body 1 having a magnet 2 at the bottom, an electric drill 3 supported by the body 1 so as to be movable up and down, and an electric drill 3 that can be moved up and down. The electric drill 3 includes a handle 4, a spindle 10 which is the output shaft of the electric drill 3, and a rotating blade 6, such as a hole saw, attached to the tip of the spindle 10.

The magnet 2 is energized to attract the workpiece 5, the spindle 10 and the rotary blade 6 are rotated by the electric motor (not shown) in the electric drill 3, and the feed handle 4 applies thrust to the rotary blade 6 to perform drilling work. .

Spindle 10 is gear cover 1 of electric drill 3
2 and needle bearings 13 and 15 fixed to the front cover 14, and rotational force is transmitted through the gear 11.

The first ball sleeve 16 is fixed to the spindle 10 by press fitting or the like, and the second ball sleeve 19 is provided so as to be slidable in the axial direction on the spindle 10 using a key 20, and is urged downward by a first spring 22. There is. Second ball sleeve 19
A thrust bearing 21 is provided between the upper surface of the gear cover 12 and the gear cover 12.

The retainer 17 includes a first ball sleeve 16 and a second ball sleeve 16.
The steel balls 18 are rotatably attached to the middle portion of the ball sleeve 19, and rotatably housed in a plurality of ball support holes 17a formed at regular intervals in the circumferential direction.

The steel ball 18 is attached to the first ball sleeve 1
6. The annular raceway surfaces 16a and 19a formed on the second ball sleeve 19 and the cylindrical inner surface 14a formed on the inside of the front cover 14 contact and hold each other, and the rolling friction caused by this contact causes rotation on the outer periphery of the spindle 10. It revolves while doing so.

Annular raceway surface 16a of first ball sleeve 16
Cam relief portions 16b are formed at the same intervals as the intervals at which the steel balls 18 are arranged and are recessed by a minute amount δ.

When the spindle 10 rotates, the annular raceway surface 16
Due to the difference in diameter between a, 19b and the cylindrical inner surface 14a, the retainer 17 and the steel balls 18 lag behind the rotation of the spindle 10. As a result, the steel ball 18 moves to the cam relief portion 16b.
When the second ball sleeve 19 reaches the first position,
It is pushed down by the spring 22, and a gap δ is created between the thrust bearing 21 and the second ball sleeve 19. Therefore, the thrust force by the handle 4 no longer acts on the spindle 10, and the cutting reaction force acting on the rotary blade 6 causes the rotary blade 6, that is, the spindle 10 to move by the gap δ, that is, the second ball sleeve 19 is moved from the thrust bearing. It rises instantaneously until it hits 21. As a result,
The rotary blade 6 instantly leaves the cutting position and cuts the cutting chips. Note that when the steel ball 18 leaves the cam relief portion 16b and returns to the original annular raceway surface 16a, the spindle 10, that is, the rotary blade 6 moves down to the cutting position and resumes cutting.

The amount of minute recess (δ in FIG. 4) of the cam relief portion 16b may be made slightly larger than the thickness of the cutting chips. If the value of δ is too large, reaction will be transmitted to the feed handle 4, making it undesirable for operation. According to experimental results using a magnetic drilling machine, it is 0.1
Approximately mm is a reasonable value.

The period in which the steel ball 18 aligns with the cam relief portion 16b and the entire spindle 10 moves by a small amount as the spindle 10 rotates depends on the contact pressure angle between the steel ball 18 and the annular raceway surfaces 16a and 19a, and the contact pressure angle between the steel ball 18 and the annular raceways 16a and 19a. Annular raceway surfaces 16, 19
Although it varies somewhat depending on the rolling friction force between the roller a and the cylindrical inner surface 14a, the rate is approximately once per rotation.

The center pin 7, the second spring 8, and the center pin guide 9 are members for positioning the hole and discharging the cutting waste after the hole is completed, and the oil filler port 10a is a through hole for feeding cutting oil to the cutting edge. be.

[Effect of idea]

As described above, according to the present invention, the combination of the annular raceway surface formed on the ball sleeve, the cam relief part, the cylindrical inner surface, and the spindle reduces the number of parts that move the cutting edge by a minute amount at a rate of approximately once per rotation. Since a small and compact chip break mechanism is built-in, it is possible to provide a magnetic drilling machine with smooth discharge of cutting chips, no chips getting entangled with the cutting edge, good operability, and high drilling efficiency. In addition, cutting chips are cut at a predetermined period to prevent chips from getting entangled with the cutting edge.
The electric motor will no longer lock up. As a result,
There is no fear that the magnet will come off and the magnetic drilling machine body will be swung around and fall, and a safe magnetic drilling machine can be provided.

[Brief explanation of the drawing]

Figure 1 is a side view of the magnetic drilling machine, Figure 2 is a longitudinal side view of the built-in part of the chip break mechanism, and Figure 3 is a side view of the internal part of the chip break mechanism.
The figure is an exploded perspective view of the chip break mechanism, part 4.
The figure is a developed view of a cross section along the axis of the circumference of the annular orbit. In the figure, 6 is a rotating blade, 7 is a center pin,
8 is a second spring, 10 is a spindle, 16 is a first ball sleeve, 17 is a retainer, 18 is a steel ball, 19 is a second ball sleeve, 20
is a key, and 22 is a first spring.

Claims (1)

[Claims for Utility Model Registration] A magnetic drilling machine body having a magnet attracted to the workpiece at the bottom, an electric drill supported by the magnetic drilling machine body so as to be able to move up and down, and driven by an electric motor inside the electric drill. A magnetic drilling machine comprising a hollow spindle, a rotary cutter and a center pin attached to the outer periphery and center of the tip of the spindle, respectively, and an annular raceway surface fixed to the spindle and perpendicular to the axis of the spindle, and the annular raceway. A first ball sleeve provided with a plurality of cam relief portions formed on a surface, and an annular raceway surface opposing the annular raceway surface of the first ball sleeve, the first ball sleeve being slidable along the spindle in the axial direction. a second ball sleeve inserted into the ball sleeve, a plurality of steel balls rotatably provided in a space formed by the annular raceway surfaces of these ball sleeves and the cylindrical inner wall of the fuselage, and a retainer that holds these steel balls. A magnetic drilling machine comprising: a first spring that presses the second ball sleeve; and a second spring that is provided within the spindle and presses the center pin.