KR100706119B1 - Rolling hammer drill - Google Patents

Abstract

The rolling hammer drill has a rolling contact at the contact surface for transmitting axial force (axial force) between the drive shaft and the wavelace. Since roller bearings are used, line contact is made. Thus, the contact area is near zero, as opposed to a relatively large area in a coupling system using toothed surfaces. This point or line contact reduces heat generation and energy loss due to friction.

Rolling hammer drill, drive shaft, roller bearing, wave race, line contact, point contact, axial force, lubrication part

Description

Rolling Hammer Drill {ROLLING HAMMER DRILL}

1 is a cross-sectional view of a rolling hammer drill according to the present invention,

2 is a detailed perspective view of the roller hub assembly;

3A, 3B and 3C are detailed perspective views of a wave race,

Figure 4a is a detailed perspective view showing a portion of the wave race to engage the roller hub assembly,

Figure 4b is a detailed view showing the interaction of the roller bearing and wave race, the roller bearing and wave race and the lubricating film,

Figure 5a is a simplified diagram showing one rotation of the rolling hammer drill,

5B is an illustration of the impact frequency of the rolling hammer drill.

          ※ Explanation of Main Drawing References ※

12 housing 14 drive assembly

16: hammer assembly 18: drive shaft

42: wave race 43: roller slide groove

45: torque transmission roller 22: bearing housing

32: roller hub assembly 38: roller bearing

34: snap ring

The present invention relates to a hammer drill having a rolling contact for transmitting an axial force (axial force) between a drive shaft and a wave race.
What is well known as a hammer drill is a hammer drill which rotates the tooth surfaces facing each other and strikes. In addition, rotary impact hammers having a ball on the tooth engaging portion disclosed in U.S. Patent Nos. 3,149,681 and 3,133,602 operate only in one direction of rotation. The bowl combined with the teeth wears out the grooves between the teeth, which forms a large contact area between the bowl and the teeth. This large contact area makes the tooth surface floating and motionless, increasing friction and heat generation of the mechanism.

Another hammer drill is disclosed in US Pat. No. 6,684,964, the striking operation of which is accomplished by the impact of multiple sets of bearings facing each other. This design increases wear and friction losses by impacting each other on the bearings.

The present invention relates to a hammer drill using a rolling hammer operation. The rolling hammer is based on the journal bearing support principle, and the reciprocation required for hammer drilling causes high impact load and vibration. Wear is accelerated whenever substantial rolling contact or a persistent hydrodynamic film is not maintained. In particular, this phenomenon occurs in sliding lamp or ratchet designs when the contact is interrupted as the lamps are separated at the end of each stroke. Similar situations occur inside the piston as the piston reverses in one direction at the beginning and end of each stroke.

The original rolling contact formed by the rolling hammer according to the present invention provides full fluid lubrication for journals and true rolling support functions, reducing friction and wear and providing longer service life than comparable products (at operating temperatures Distributing and distributing the heating heat, which has an adverse effect, allowable speed and journal and the original rolling functions.

Rolling hammer drills are a simple, unusual and easily constructed mechanism. These rolling hammer drills produce powerful single impact energy with precise impact vibrations that result in relatively high removal rates and extend drill bit life regardless of size. The rolling hammer drill can be constructed with strokes of various sizes and shock vibrations for a wide range of applications with only minimal design changes. In particular, rolling hammer drills have a smooth rolling curve, which results in better and lower vibrations and better shaped impact pulses to drill holes more satisfactorily. Reducing the uncontrolled breakage of concrete during the drilling process is another advantage. This rolling hammer drill is maintenance-free and has an efficient and long service life with a suitable manufacturing cost for industrial, commercial and residential applications.

Therefore, in the rolling hammer drill according to one aspect of the present invention, rolling contact portions are formed on the contact surfaces for the transmission of the axial force between the drive shaft and the wave race. Since roller bearings are used, line contact is made. This area of contact thus approximates zero, as opposed to a relatively large area of the coupling system using serrated surfaces. The use of point or line contact reduces heat generation and reduces energy losses due to friction.

In some prior art products, the release clutch relieves torque when the pressure increases above the threshold and prevents the joints from shearing. For hammer drills with rolling contacts, relatively low torque generators can be used, in which case the torque does not exceed the shear stress.

The rolling hammer drill of the present invention does not require a release clutch because it can provide the same function by rolling friction. As the torque increases, the roller bearings installed in the stationary roller hub as part of the drive assembly push the wavelace into the hammer assembly, thereby separating the hammer assembly from the drive assembly and freeing it from the torque. In addition, this repeat operation causes a hammer effect. The contact points between the rotating bearing element and the wavelace will be between 0 and 90 degrees with respect to the tool axis. This deviation causes the shear component of the reaction force to rotate the roller bearings in their cavity in the roller hub assembly. These rotating bearing elements are prevented from axial movement with respect to the roller hub, but are free to rotate in the cavity of the roller hub.

Various aspects of the invention are described in the following detailed description of the invention and claimed in the claims.

The present invention will be described in detail with reference to the accompanying drawings.

As used herein, the word "comprising" is used in a non-limiting sense to mean that the items after this word in a particular sentence are included, as well as meaning that items not specifically mentioned are not excluded.

The use of the indefinite article "a" in front of an element (component) in the claims means that one of the elements is being specified, but is present among the elements that are present unless it is clear that the text will be one or only one of these elements It does not mean to exclude other elements.

Referring to Figure 1, a roller drill adapter is shown, in which two subassemblies are installed in a housing 12. The drive assembly 14 is directly connected to the chuck or power tool (not shown) of the drill and transmits torque from the drill to the hammer assembly 16. The hammer assembly 16 converts the received torque into its own torque and axial stroke motion. The drive assembly 14 may be integral with the power tool.

The drive assembly 14 has a drive shaft 18 whose one end is formed into a hexagonal cross section for connection with a chuck of a conventional power tool. The other end of the drive shaft 18 is formed with a pocket arranged in the roller slide grooves 43 are formed at regular intervals separated by three equal intervals to accommodate the three torque transmission rollers (45).

The torque transfer roller 45 is coupled to the roller slide groove 43 (not shown in FIG. 1), but rotatably fixes the wave race 42 to the drive shaft 18 shown in FIGS. 3A and 3C. . The middle section of the drive shaft 18 is circular in cross section and is fixed in a bearing housing 22 which supports the drive shaft 18 in the housing 12 to rotate about the housing 12. The bearing housing 22 is supported in place on the drive shaft 18 by the shoulder 20, for example a ball bearing may be used.

The housing 12 has a cylindrical shape and is formed with a circular threaded opening through which the roller hub assembly 32 is spirally inserted. The snap ring 34 is engaged with the groove 36 formed in the drive shaft 18 to fix the roller hub assembly 32 in place, and to be axially fixed with respect to the drive shaft 18, and at the same time the roller hub assembly 32. ) Is rotatably fixed relative to the housing 12.

The roller hub assembly 32 is secured by being fitted into the opening of the bearing housing and there are formed twelve circularly arranged cavities that hold the twelve roller bearings 38 in place as shown in FIG. The roller hub assembly 32 is also formed with an opening for fixing the bearing housing 22.

As shown in FIGS. 3A and 3B, the hammer assembly 16 has an appearance adapted to form the wavelace 32.

The roller slide grooves 43 of the hammer assembly 16 and the torque transfer rollers 45 of the drive shaft 18 allow the drive assembly 14 and the drive shaft 18 to rotate together, and at the same time relative between them. Allow axial movement. The operating end 50 of the hammer assembly 16 is formed with spirals of the 1 / 2-20UN standard.

As shown in FIG. 2, the bearing housing 22 has twelve circularly arranged cavities for positioning twelve roller bearings 38. The bearing housing 22 is supported on the hammer assembly 16 together with the needle bearing 54 to allow relative rotational movement of the housing 12 relative to the hammer assembly 16.

The drive shaft 18 receives torque from a power source (portable drill or electric motor) and transfers it to the hammer assembly 16 by the torque transfer rollers 45. The roller hub assembly 32 is supported in a stable state because it is screwed with respect to the housing 12. The roller bearings 38 are free to rotate in the cavities in the roller hub assembly 32. The roller hub assembly 32 is supported against axial movement on the drive shaft 18 by the snap ring 34.

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When the drive shaft 18 rotates, the hammer assembly 16 rotates with the drive shaft 18. The housing 12 is threadedly coupled with the bearing housing 22 therein while being firmly fixed by hand, thereby supporting the bearing housing 22 corresponding to the rotation against the rotation of the drive shaft 18. The roller 38 then rotates relative to the wavelace 42. Since axial pressure is applied on the drive shaft 18 and the hammer assembly 16, the wave portion Wave on the wavelace 42 is initially located in the gap between the roller bearings 38. As the wave race 42 rotates, the roller bearings 38 ride as the wave portions of the wave race 42 move up and down, causing axial movement of the hammer assembly 16 with respect to the drive shaft 18. Axial displacement is a function of the size of the roller bearing and the racewave amplitude.

The lubrication portion is formed inside the hammer assembly 16 by the cavity 80 so that the lubricating oil can be supplied through the through hole 82 between the wave race 42 and the drive shaft 18.

As shown in FIG. 3B, the through hole 82 is formed in the wavelace 42 perpendicular to the central axis of the hammer assembly 16. The through hole 82 is formed to extend from the low oil storage 84 to the outside. The reciprocating operation of the hammer assembly 16 with respect to the drive shaft 18 has a vacuum effect, injecting lubricant from the low oil reservoir 84 into the cavity 80 via the through hole 82 and then driving the drive shaft 18. Accordingly, the wave race 42 and the bearing 18 are attracted.

3A, a detailed perspective view of the hammer assembly 16 shows a corrugated raceway 41 forming the outline of the wavelace 42. As shown in FIG. Corrugated raceway 41 is also shown in FIG. 3B. This corrugated raceway 41 is composed of twelve identical sinusoidal cycles with an amplitude of 0.120 ".

Referring to FIG. 4A, the rolling hammer drill is shown in detail with the disassembled hammer assembly 14 in part so as to be clearly represented. Twelve roller bearings 38 are installed as independent journals in the stationary roller hub assembly 32 with the rotary wavelaces 42 causing a hammer drill operation. A continuous lubrication membrane is supported in the cavity of each roller bearing by a consistent support shape with the rotation of the continuous and unobstructed roller bearing.

4B, wavelace 42 makes the rotation shown. The result depends on the mechanism in which one side of each roller bearing 38 is in original rolling contact with the wavelace, while the other side of the roller bearing 38 is connected to the continuous hydrodynamic lubrication membrane of the journal bearing support. Is supported. The force from the wavelace is shown in the W section. The rotation direction of the roller bearing 38 is shown by the drum N. As shown in FIG. When the journal bearing starts to rotate, there is very little lubricant between the journal and the pocket at the contact point h0, and friction occurs. Therefore, considerable friction generated when operating the hydrodynamic journal bearing must be overcome. When this bearing reaches a sufficient speed, the lubricant begins to be inserted into the contact areas marked with dark black lines on the wavelace and roller hub assemblies. The roller bearings 38 of the roller hub assembly 32 are not completely surrounded by their journals. The ruptured lubrication film is restored to its original shape by a wave race 42 that is partially arcuate, very similar to the unfinished portion of the journal. Hydrodynamic lift is achieved and maintained in a continuous film of lubricant.

The use of roller bearing joints reduces friction, which generates heat and causes energy losses.

The formula for calculating the energy generated by friction is as follows.

E = K × F × A

Where F = action force

        A = contact area

        K = friction coefficient

        E = energy

As can be seen from the equation, all given components must be minimized to obtain the minimum energy. The action force is the result of the pressure exerted by the operator through the tool that is placed on the perforated opening surface and thus cannot be minimized. The coefficient of friction is a function of the material, surface class and operating characteristics (pull or rotation). In the case of the engagement of a bowl bearing or a roller bearing, the coefficient of friction is minimized for the reason;

a) the roller bearing has a flatter surface than the teeth at the teeth and toothed parts,

b) The roller bearing engagement provides a rolling (rotating) action opposite to the direction in which the teeth and teeth are pulled in the engagement.

The coefficient of friction is significantly lower with the roller bearing coupling than with the teeth and tooth coupling.

Referring to Fig. 5A, an illustration of one rotation of a rolling hammer drill using twelve roller bearings is shown.

Fig. 5B is a detailed illustration of the impact pulse shape of the rolling hammer drill that occurs at each point where the roller bearing engages the polymorph portion in the wave race.

In Figure 5b,

A is the flat curve at the start of the impact,

B is the flat transition to the peak amplitude,

C is an amplitude that is held to a predetermined point of the next period following the flat transition portion,

D is the flat finished part of the period,

E indicates that the amplitude and shape of the pulse depends on the number of rollers used and the shape of the wavelace, and a wide variety of designs are possible for different applications.

Flat impacts across the corrugated sections appearing in cycles result in relatively fast drilling, improved hole geometry, reduced vehicle fatigue and longer drill bit life.

Those skilled in the art can make substantial modifications in accordance with the invention described in this patent specification without departing from the spirit of the invention.

Claims (7)

1. For rolling hammer drill, housing; A drive shaft having one shaft to rotate relative to the housing within the housing and supported by the bearing; A set of rotating roller bearing elements supported in the housing and movably fixed relative to the housing and arranged in a plane perpendicular to the axis of the drive shaft; A hammer assembly coupled with the wavelace, supported within the housing for axial and rotational movement with respect to the housing, for driving the drive shaft to be connected thereto, and for axial movement between the drive shaft and the , And the rotating roller bearing elements and wavelaces are coupled to face each other in the housing as they rotate on the shaft to support the drive shaft and the hammer assembly, thereby operating a hammer against the hammer assembly. The method of claim 1, Rolling hammer drills with rotating roller bearing elements in roller bearings. The method of claim 1, Rolling hammer drills with a wave race to a roller bearing surface that follows a sinusoidal shape. Rolling hammer drills with a wave race to a flat roller bearing surface. The method of claim 4, wherein Rolling hammer drill with roller bearing surfaces consisting of peaks and troughs arranged at equal intervals. The method of claim 1, Rolling hammer drill in which force (axial force) is transmitted to the wave race only via the contact between the rotating roller bearing element and the wave race from the drive shaft. Rolling hammer drill in which the drive shaft becomes the drive shaft of a power tool such as a power motor.

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