JPS6210767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical assembly-type cutting tool in which blades having independent cutting edges are spirally embedded in the outer peripheral surface of a main body.

An integrated cutting tool that has been subjected to double-cut grinding, such as a hob, requires fewer re-grinds due to the cam-cutting part and has a short lifespan.Therefore, various assembled tools without a cam-cutting part have been proposed. Since the hob is a generating-type gear cutting tool with cutting edges arranged in a spiral, space is limited in order to assemble the blade and main body, and it is difficult to find a way to fix the blade to the main body. .

Therefore, as shown in FIG. 5, what has been proposed in the past is to separate the blade portion in the axial direction, press fit the blade 2' into the main body 1' in the longitudinal direction, and attach the lug portions 4' of the blade 2' to both ends. In some cases, an annular presser foot 3' is coated with adhesive and screwed to the main body 1', or an annular ring is used to connect the main body 1' and the blade 2' by means such as shrink fitting. In addition, as shown in Fig. 6, a blade 2 is made with a set of multiple blades, and the two cylindrical portions between the blades are connected to the main body with bolts 2', and these are inserted into the spiral groove formed in the main body 1 at multiple points. Some are arranged. (Japanese Patent Publication No. 57-102722).

However, in the former case, since both ends are only forcibly fixed, the hob may float in the center during cutting or cause slight vibrations, which may cause a defective tooth profile. Furthermore, press fit the blade 2' into the main body 1', and attach both ends to the main body 1'.
Because the hob is crimped, a large stress remains throughout the hob, making it susceptible to deformation.

In addition, the latter has blades arranged in a spiral direction, each with two blades.
Although it is fixed in place, both ends are not fixed, so slight vibrations are likely to occur when strong cutting force is applied to both ends. Particularly, one of the major purposes for making the blade part assemblage type is to use a super hard alloy for the blade part, and in such a case, micro-vibration is particularly undesirable as it can cause chipping or chipping of the blade.

In this invention, a blade positioning pin driving hole is formed at the bottom of a spiral groove formed on the outer peripheral surface of the main body, a pin hole corresponding to the positioning pin hole is formed at the bottom of the blade, and at both ends of each blade. This is a cylindrical assembly-type cutting tool with semicircular bolt holes drilled and both ends of adjacent blades fixed with a single bolt.It has excellent rigidity, good workability, and high accuracy, except for the above drawbacks. The aim is to provide easy-to-assemble tools at low cost.

Embodiments in which the cylindrical assembly-type cutting tool according to the present invention is applied to a hob will be described below with reference to FIGS. 1 to 4.
This will be explained based on the diagram. The main body 1 has a hole 3, a hole key 4, and an end face key 5 at the axial center thereof for attachment to a gear cutter (not shown). Further, a spiral groove 9 for inserting a blade is bored in the outer circumferential surface 7 of the main body 1 and has an axial pitch 8 equal to the axial pitch of the hob. The twist of the side wall 10 of the spiral groove 9 is the groove bottom surface 1.
It becomes weaker as it goes from 1 to the outer peripheral surface 7.
The relationship is such that the axial pitch 8 is kept constant and the side wall 10
If screw grinding is carried out in such a way that interference with the grindstone does not occur, this relationship is inevitably determined by determining the diameter of the groove bottom surface 11 and the diameter of the outer circumferential surface 7.

The blade 2 installed in the spiral groove is configured as a unit with one or more base parts. In the blade 2 shown in FIG. 4, a single base 25 forms a blade 2, and is shaped so that it can be fitted into a spiral groove 9.

Furthermore, a pin driving hole 12 is drilled in the center of the blade insertion groove 9 to determine the position of the blade 2 and to receive the cutting force applied to the blade 2, and the number of blades is smaller than the number determined in the hob design. A large number of holes are drilled at equal intervals, and two washers are placed at both ends of the spiral groove.
3 is for installation. At this time, in order to drill the pin driving holes so that their centers are lined up at an angle of β with the axis, the division angle θ in the direction perpendicular to the axis is determined by the following formula.

θ=2πR-Pa・sinβ・cosγ/R・N
(Radians) However, Pa: Axial pitch R: Radius of bottom surface (11) N: Number of grooves in the hob γ: Helix angle on the bottom surface β: Helix angle on the pitch circle of the hob.

Next, when the blade 2 is positioned with the pin 18, screw holes 13 are bored so as to fit into the semicircular bolt holes 14 provided at both ends, and both ends of the blade 2 are tightened with bolts.

Furthermore, a pin 18 is driven into the pin hole 12 of the bottom surface 11 of the spiral groove in the center of the bottom surface 15 of the blade 2.
A pin hole 19 is drilled to fit the blade 2, and a bolt 2 is inserted at both ends of the blade 2 in the axial direction of the main body 1.
1, a semicircular bolt hole 20 and a semicircular bolt hole 14 are provided for crimping.

At this time, the depths of the counterbore holes 20 are made to be the same since the ends of adjacent blades 2 are tightened with one bolt.

Each part made in this way is manufactured by first driving a pin 18 into a pin hole 19 drilled in the bottom surface 11 of the spiral groove, and inserting the blade 2 into the spiral groove 9 with the cutting edge facing the direction of rotation of the hob. Insert it, make sure that the pin hole 19 fits into the pin 18, and push it in until the bottom surface 15 of the blade and the spiral groove bottom surface 11 are in close contact.
In this way, insert the blades 2 one after another, insert the disc spring washer 22 into the bolt hole formed at the boundary between the blades 2, and screw the bolt 21 into the screw hole 13 drilled in the bottom surface 15 of the blade insertion groove. Enter,
Tighten it temporarily.

When all the blades 2 are inserted, the first and last blades 2 do not have adjacent blades on one side, so they have the same shape as the end of the blade 2, and insert a washer 23 with a pin hole 19 in the same way as between the blades. After temporarily tightening the bolts 21, all the bolts 21 are fully tightened to complete the assembly.

Note that the bottom surface 15 of the blade 2 has a spiral groove 9, and a grindstone formed to have a radius slightly smaller than the radius of the bottom surface 11 is passed through the blade 2 in a direction of 90°±β relative to the longitudinal center line of the blade 2 to form a spiral groove on both ends. The (±)β that provides a surface with good contact is determined by the twist direction. The side surface 16 of the blade 2 has the same axial pitch 8 as the body 1 with a protruding strip that fits into a pin hole 17 provided in the center of the bottom surface 15 of the blade on a cylinder of the same diameter as the bottom surface 11 of the helical groove. By attaching the blade 2 to a helical grinding jig and grinding it, a curved surface exactly the same as the blade insertion groove side wall 10 can be obtained.

At this time, by leaving a small portion of the strip of the jig that touches both ends of the blade 2 and removing the rest, the spiral strip and the keyway 17 machined straight fit together with almost no error. Moreover, by increasing the width of the jig, any number of pieces can be ground in one go, so the grinding cost per piece is small.

As described above, the present invention has a blade positioning pin driving hole drilled at the bottom of the spiral groove, a pin hole corresponding to the positioning pin hole drilled at the bottom of the blade, and semicircular bolts at both ends of each blade. Since the holes are drilled and both ends of adjacent blades can be fixed with a single bolt, the complicated mating surfaces between the blade and the main body are perfectly aligned, and since they are connected with pins and bolts, it is very easy to use. It has become highly rigid. Furthermore, since the rigidity is increased, slight vibrations are less likely to occur, and defects in accuracy of the workpiece, such as defective tooth profile (in the case of a hob), do not occur.

Moreover, the blade insertion groove on the main body is precisely thread-ground, and the blade fitting surface is also installed under the same conditions as the blade insertion groove on the main body by using a jig to install one set plus a spare at the same time. The blades are all ground to the same dimensions.
Therefore, if chipping or chipping of the blade occurs in the mid-cutting blade, as with conventional products, the blade can be easily and accurately replaced or replaced with a spare blade without removing the hob from the hob shaft.

In addition, it is highly rigid and does not cause slight vibrations, so it is suitable for using a throw-away method in which the cutting blade is made of cemented carbide.If the throw-away method is used, only the cutting tip can be replaced, making work even easier. It is very economical as it improves the performance and reduces the total cost.

[Brief explanation of the drawing]

Fig. 1 is a front view of a main body according to an embodiment of the present invention partially cut away in the helical direction, Fig. 2 is a sectional view of half of the main body, and Fig. 3 is an assembly mechanism of an embodiment of the present invention viewed from the torsional direction. FIG. 4 is a partially assembled front view and partial axial sectional view of the embodiment, FIG. 5 is an axial sectional view of a conventional assembled hob, and FIG. 6 is a conventional product of another shape. Part of the assembly hob blade and assembly mechanism. 1... Body, 2... Blade, 3... Hob mounting hole, 7... Outer circumferential surface, 8... Axial pitch, 9...
Spiral groove, 11...Spiral groove bottom, 12...Pin driving hole, 13...Screw hole, 14...Bolt hole, 15...
...Bottom of the blade, 18...Pin, 19...Blade pin hole, 20...Semicircular bolt hole, 21...
Bolt, 23... washer, 24... cutting blade.

Claims (1)

[Claims] 1 A cylindrical assembly type cutting tool in which a spiral groove with an axial pitch equal to the axial pitch of the blade is formed on the outer peripheral surface of the main body, a plurality of blades are inserted into the spiral groove, and the blades are fixed with bolts. , a blade positioning pin driving hole is drilled on the bottom of the spiral groove,
A pin hole corresponding to the positioning pin hole was drilled on the bottom of the blade, and semicircular bolt holes were drilled at both ends of each blade, making it possible to fix both ends of adjacent blades with a single bolt. A cylindrical assembly type cutting tool characterized by: