CN103600334B - Etc. wave resistance drill bit - Google Patents

Abstract

The wave resistance drill bits such as one, including integrally formed drillstock (1) and drill body (2) and the drill lip (3) being located at drill body (2) front end, the upper processing of drill body (2) has helical flute (4), helical flute (4) on drill body (2) extends to the junction of drill body (2) and drillstock (1), and the ratio of the cross-sectional area of drillstock (1) and described drill body (2) is 0.9～1, the wave resistance making drill body part is close or equal with the wave resistance of described drillstock part, thus such wave resistance drill bit is able to ensure that raising penetration efficiency。

Description

Etc. wave resistance drill bit

Technical field

The present invention relates to a kind of drill bit, specifically the wave resistance drill bit such as a kind of, it can significantly increase penetration efficiency。

Background technology

Electric hammer drill for holing on the fragile material such as concrete, rock。Electric hammer is to produce stress wave in drill bit one end by high-speed impact, and the stress wave containing energy is propagated to drill lip by drillstock, drill bit, and drill lip makes concrete, the rock etc. that contact broken。

At present, the drill bit that engineering uses, the helical flute 4 on drill body 2 does not have machining to drillstock 1, but in the local ending from drillstock 1 certain distance, causes drill body 2 to leave one section of polished rod near drillstock 1, referring to Fig. 1。So, analyzing from the propagation angle of stress wave, the direction hindering stress wave direction drill lip 3 is propagated by this section of polished rod on drill body 2, thus reduces the working (machining) efficiency of electric hammer。

Summary of the invention

In order to overcome above-mentioned existing drill bit deficiency structurally, solving the technical problem that its penetration efficiency is low, the present invention provides the wave resistance drill bit such as a kind of, its by reduce or eliminate drill body part and drill shank divide between wave resistance, improve the penetration efficiency of drill bit。

The present invention etc. wave resistance drill bit, including integrally formed drillstock, drill body and drill lip, described drill body is provided with helical flute, and described drill lip is arranged on the front end of described drill body, it is characterised in that: the described helical flute on described drill body extends to the junction of described drill body and described drillstock。

Further, described drillstock is 0.9～1 with the ratio of the cross-sectional area of described drill body so that the wave resistance of described drill body part is close or equal with the wave resistance of described drillstock part。

Owing to helical flute makes the cross-sectional area of drill body reduce, and make drill body and the two-part cross-sectional area of drillstock close, thus be conducive to stress wave to be propagated to drill lip by drillstock such that it is able to improve the work efficiency of electric hammer。

Compared with the drill bit of prior art, the present invention, from the rule of stress wave propagation, by using the attachment structure of new drillstock and drill body, considerably improves the penetration efficiency of drill bit。

Accompanying drawing explanation

Fig. 1 is the structural representation of the conventional drill of prior art；

Fig. 2 is the structural representation of the wave resistance drill bits such as the present invention；

Fig. 3 is the stress wave propagation situation at wave resistance abrupt interface of the wave resistance drill bits such as the present invention；

Fig. 4 is the mechanical model of the wave resistance drill bits such as the present invention；

Fig. 5 is the reflection wave in the drillstock of the wave resistance drill bits such as the present invention；

Fig. 6 is the wave resistance drill bits such as the present invention and the ballistic work of conventional drill contrasts；

Fig. 7 is the wave resistance drill bits such as the present invention and the penetration efficiency of conventional drill contrasts。

In figure: 1-drillstock, 2-drill body, 3-drill lip, 4-helical flute。

Detailed description of the invention

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is done further detailed description。

As in figure 2 it is shown, the present invention etc. wave resistance drill bit include drillstock 1 and drill body 2, drill body 2 is machined with helical flute 4, the front end of drill body 2 is provided with drill lip 3, and particularly, the helical flute 4 on drill body 2 processes the junction extending to drill body 2 with drillstock 1 always。

And, the present invention etc. wave resistance drill bit, the ratio of drillstock 1 and the cross-sectional area of drill body 2 is 0.9～1 so that the wave resistance of drill body part and the wave resistance of described drillstock part close to or equal。

Below, in conjunction with Fig. 3-7, to the present invention etc. the wave mechanics of wave resistance drill bit be analyzed。

The wave resistance drill bit such as provided by the invention, its wave mechanics basis includes three below aspect:

One, the foundation of wave mechanics research drill bit is applied；

Two, stress wave is at the propagation law of wave resistance sudden change unit interface；

Three, stress wave propagation law in drill bit。

Specifically, above-mentioned first aspect includes:

The operation principle of electric hammer is to utilize the instantaneous stress wave pulse produced of clashing into completed to make working media produce to crush。The parts (particularly drill bit) participating in electric hammer clashing into are more much bigger than lateral dimension in the size of crash direction, and it is the impulse machine of a quasi-representative。Therefore, the Impact Problems in electric hammer work process must be explained by wave mechanics theory。

Specifically, above-mentioned second aspect includes:

Stress wave has the interface of sudden change will produce transmission and reflection in wave resistance, as shown in Figure 3。When a stress wave is Z from wave resistance_iElastic rod be Z to wave resistance_i+1Elastic rod when propagating, change the transmission coefficient on interface and reflection coefficient is respectively as follows: in wave resistance

${\mathrm{\μ}}_{i,i+1}=\frac{{2Z}_{i+1}}{Z_i+Z_{i+1}}---\left(1\right)$

${\mathrm{\λ}}_{i,i+1}=\frac{Z_{i+1}-Z_i}{Z_i+Z_{i+1}}---\left(2\right)$

In formula: μ-transmission coefficient；

λ-reflection coefficient。

From formula (1): the direction of propagation of transmitted wave is identical with incidence wave, symbol is too。But echo is not so, its direction of propagation is always contrary with incidence wave, and symbol can just can be born, and will become big depending on wave resistance or diminish。Work as Z_i< Z_i+1, when namely stress wave is propagated to big wave resistance by little wave resistance, transmitted wave symbol is identical with incidence wave symbol；Work as Z_i> Z_i+1, when namely stress wave is propagated to little wave resistance by big wave resistance, transmitted wave symbol is contrary with incidence wave symbol。

For ripple P, can obtain in the change transflector relation at interface of wave resistance according to stress wave:

P_t=μ_{I, i+1}P_i(3)

Q_r=λ_{I, i+1}P_i(4)

In formula: P_i-incidence wave；

P_t-transmitted wave；

Q_r-echo。

Specifically, the above-mentioned third aspect includes:

For the drill bit shown in Fig. 1, in Wave dynamics analysis, its drillstock, drill body, drill lip can being reduced to cylinder respectively, such drill bit can be considered the elastic rod of three sections of cylinder, as shown in Figure 4, described drillstock, drill body, drill lip part wave resistance use Z respectively₁、Z₂、Z₃Represent。

Propagation law according to stress wave, will there is transmission and the reflection of ripple in stress wave when running into wave resistance (cross section) and changing。Stress wave is Z from wave resistance_iPart be Z to wave resistance_i+1Part propagate time transmission coefficient and reflection coefficient can according to formula (1), formula (2) calculate。

Deriving in order to convenient, here the ripple propagated towards bit operation extreme direction is called incidence wave P, the ripple contrary with the direction is called echo Q。The incidence wave P come is propagated from bit hits end face₁After arriving at drillstock and drill body interface, a part, transmitted through this interface, forms incidence wave P₂, a part reflects to form echo Q at this interface₁。Incidence wave P₂After arriving at drill body and drill lip interface, after producing transflector, form incidence wave P₃With echo Q₂。Echo Q₂After returning to the interface of drillstock and drill body, form echo Q₃And incidence wave P₄。Incidence wave P₄Experiencing a transmission and reflect to form for twice, its value is compared to incidence wave P₁Only small, therefore do not consider further that incidence wave P₄Propagation condition。Echo Q₁With echo Q₃It is incidence wave P₁At the echo that the interface of two wave resistance changes is formed, its value can calculate according to the following formula。

Q₁=λ_1,2·P₁(5)

Q₃=u_1,2·λ_2,3·u_2,1·P₁(6)

The length of drillstock is less, if ignoring echo Q₁With echo Q₃At the priority difference of time, total echo Q₄It is echo Q₁With echo Q₃Superposition, its value can calculate according to the following formula。

Q₄=Q₁+Q₃(7)

When bit diameter is less, echo Q₄For tensile wave, after this ripple arrives at bit hits end face, tensile wave can make bit hits end face move towards the direction separated with jumper bar, now bit hits end face becomes free end, tensile wave will be reflected into equal-sized compressional wave, this ripple will continue to propagate towards bit operation end, and the energy of echo can be retained in drill bit。When bit diameter is bigger, echo Q₄For compressional wave, compressional wave will make bit hits end face move towards jumper bar direction, is transmitted in jumper bar by part stress wave, and return jumper bar along with part energy, and namely this be that drill bit makes electric hammer ballistic work reduce reason quickly。

When bit diameter is bigger, echo is compressional wave, and fractional transmission is entered jumper bar after arriving at bit hits end face by reflected compression wave, makes the energy loss in drill bit, the reduction echo therefore tried one's best。By analysis above it can be seen that for conventional drill, owing to the wave resistance (diameter) of drill body is more than the wave resistance (diameter) of drillstock, incidence wave creates reflected compression wave in drillstock and drilling rod interface。If it is poor to reduce this two-part wave resistance, just can effectively reduce echo。

The screw thread chip area of drill lip part is the passing away of bit operation end landwaste, although the major diameter of thread of drill lip part is identical with the bar portion diameter of drill body, but the existence due to chip area, the wave resistance of drill lip part is more much smaller than the wave resistance in drill body bar portion, makes the mechanical model of drill bit present the phenomenon of " being small at both ends and big in the middle "。Part general's obstruction stress wave direction bit operation end propagation that drill bit is broad in the middle, if the screw thread chip area of drill lip part can extend to drillstock part, makes the drill body bar portion of drill bit be removed, will change the phenomenon of " being small at both ends and big in the middle ", as shown in Figure 5。After improvement etc. wave resistance drill bit only have drillstock part and drill lip part, thus corresponding echo reduces。

Example

For the electric hammer of certain model, this electric hammer supports the use the drill bit of 6 kinds of diameters, i.e. (Φ 16, Φ 20, Φ 25, Φ 30, Φ 34, Φ 38) × 500mm, at the reflection coefficient λ of drillstock 1 with drill body 2 interface_1,2With transmission coefficient μ_1,2, drill body 2 and drill lip 3 interface reflection coefficient λ_2,3With transmission coefficient μ_2,1Value as shown in table 1。

The transmission coefficient at table 1 wave resistance change interface and reflection coefficient

Table 2 is the echo size in drillstock and symbol。

The echo size of table 2 drillstock and symbol

After improvement etc. wave resistance drill bit reduce drill bit wave resistance change interface number, be conducive to energy to drill bit transmit, improve ballistic work and the penetration efficiency of electric hammer impact system, as shown in Figure 6, Figure 7。The increase rate of ballistic work and penetration efficiency improves with the increase of bit diameter, and when bit diameter is Φ 38mm, the increase rate of ballistic work and penetration efficiency reaches maximum, as shown in table 3。

The increase rate of table 3 ballistic work and penetration efficiency

Claims (1)

1. the wave resistance drill bit such as a kind, including integrally formed drillstock (1), drill body (2) and drill lip (3), described drill body (2) is provided with helical flute (4), described drill lip (3) is arranged on the front end of described drill body (2), it is characterised in that: the described helical flute (4) on described drill body (2) extends to the junction of described drill body (2) and described drillstock (1)；The ratio of the cross-sectional area of described drillstock (1) and described drill body (2) is 0.9～1, and the wave resistance of described drill body part is close or equal with the wave resistance of described drillstock part。