JPS62181824A - Method of forming screw hole by one step - Google Patents

Abstract

PURPOSE:To carry out the forming of a prepared hole for a small diameter screw and the tap of the hole in one step, by holding a drill tap composed of a drill section and a tap section, slidably onto a spindle, and by feeding the spindle at pitches which is less than the pitches of the screw thread to be formed. CONSTITUTION:A spindle 13 is rotated to be fed at pitches which is less than that of a thread to be formed, such as, for example, at a value such as, the diameter of a prepared hole X 0.02. When a drill section 2 forms a prepared hole in a workpiece 5 secured to a machine bed 6, a tap section 3 catches the workpiece 5. Further, torque is transmitted to a tap holder 8 from the spindle 13 through a key 9, so that the holder 8 is advanced by one pitch for every turn, overcoming the resistance of a spring 11. Therefore, the tap holder 8 slides in the direction in which it comes off from the spindle 13 for tap operation. When the spindle 8 is reversed, the tap holder 8 is pulled by the spring 11 one thread pitch for every turn, and is therefore retracted into the spindle 13. Further, the tap section 3 comes off from the workpiece 5 so that the thread forming process is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to tapping of a screw hole. Conventionally, relatively small-diameter screw holes have been machined by tapping using a processing tool called a tap, which is performed by cutting or plastic forming called rolling, but in both cases, tapping is performed as a pre-process. Required drilling of pilot holes. That is, machining a relatively small diameter screw hole required two steps: drilling a pilot hole and tapping the hole. Therefore, the workpiece (hereinafter referred to as the work) must first be drilled with a machine for drilling the pilot hole, and then tapped with a tapping machine for tapping. It was something I was forced to do. If it were possible to do this in one move, it would be possible to transport the workpiece to the two types of machines mentioned above, attach the workpiece to each machine,
Labor costs for removal, etc., expenses for tools and equipment used for transportation, installation, removal, etc., and fees for two types of machinery.

The land, building area, etc. required for installing the two types of machines should be roughly halved. Especially when the workpiece is long.

In the case of heavy objects, the advantage is significant.

The present invention can realize this ideal by a simple and easy method, and the present invention will be explained below based on the illustrated embodiments.

Fig. 1 shows a tapping tool (hereinafter referred to as a drill tap) used in the method of the present invention, the whole of which is indicated by ft@ (1), and the part used for drilling the pilot hole ( (hereinafter referred to as the drill part) k (2) The part used for tapping (hereinafter referred to as the tap part) 131, +11
The exposed part for gripping is (4).

Figure 2 shows the state before the start of machining, and the workpiece (5) held on the machine floor (6) is restrained from rotating by the guide handle (hereinafter referred to as the main shaft). At the same time, it is pulled into the main shaft o3 by the action of the tension spring αυ attached between the bottle dot built into the guide handle and the pin 4 built into the main shaft t13, and the end face of the main shaft (13 and the guide handle Hold the drill tap (1) in the tap holder (8+), which the shoulder of the main body adjacent to the tap holder (8+) is in close contact with, by means of a set screw (7), etc., and make it face the workpiece (5).Now, apply rotation to the main shaft (13). At the same time, the main shaft (13, and hence the drill tap (1)) is advanced toward the workpiece (5) at a rate of (S) per rotation.

Diameter of drill part (2) of drill tap tl+ (S) (
The ratio to d) is the material and hardness of the drill tap (1).

The hardness is controlled by the material of the workpiece (5), the capacity of the mechanical device, the rigidity, etc., but is approximately 2% of the diameter (d) of the drill part of the drill tap (1). That is, approximately S=0.
There is a relationship 02d (equation 1).

Drill tap il+ advances while rotating, and when it reaches workpiece (5), pilot hole drilling starts and drill tap (1)
Figure 3 shows the state in which the tip of the hole has penetrated the workpiece (5) and the pilot hole drilling has been completed. When the drill tap (1) further advances at a rate of (S) per revolution, the drill tap (1)
The tap part (3) of the drill tap (3) bites into the workpiece (5), and from this point on, the tap part (3) of the drill tap (1) is fixed because the joint (P) of the tap part (3) is smaller than the [stock]. The holder (8+) moves forward toward the tension spring (approximately P per rotation against the resistance force of the wings), and the tap holder t8+
gives rise to a tendency to escape from the main axis <13. Tap part (3
) has penetrated the workpiece (5). At this point, if the main axis (t3 is rotated in the opposite direction and simultaneously KG) is retracted away from the workpiece (5), the tap holder (On August 8th, the return drill tap fl+ to (P) per revolution was removed from the workpiece (5) and returned to the state shown in Fig. 2.

At this point, if you stop the rotation and regression of the main axis ([3), the tapping will be completed.

[Brief explanation of drawings]

Fig. 1 shows a machining tool called a drill tap used in the method of the present invention, (1) shows the entire tool, (2) shows the drill part,
(3) shows the tap part, and (4) shows the handle part. In the second stage, the drill tap (+) k is installed, and the state of the machine used before starting machining. Figure 3 is a diagram of the state when the pilot hole has been completed and tapping is about to start. Figure 4 is the state of the tap section. is a state diagram in which the tap has been completed after penetrating the workpiece (5). (1) Entire drill tap, (2) Drill portion of the drill tap, (3) Tap portion of the drill tap, (4) Handle of the drill tap, (5)・Work, (6)...Machine floor, (7)...Drill tap set screw, (8I...Tap holder, (9)...Key,
Iin...Bin, 0me...Tension spring, u'4.
・Bin, (L3... main shaft.

Claims (1)

[Claims] The amount of axial displacement per revolution (feed amount per revolution) (S) of the machining tool during tap vertical machining and the equivalent drilling of a prepared hole must be smaller than the thread pitch (P) of the tap. How to complete pilot hole drilling and tapping in one movement using