Roller shaft for brush roller

Abstract

The present invention provides a roller shaft for a brush roller, including a shaft body, wherein the outer peripheral surface of the shaft body contains at least one spirally extending groove portion for fixing a brush strip, and at least one end portion of the groove portion is a continuous curved transition, preferably a three-arc transition structure, and by changing the structure of the single arc transition line at the end portion of the groove portion, the phenomenon of highly concentrated stress can be eliminated, the bearing capacity can be improved, and the service life of the roller shaft can be extended.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum cleaners, in particular to a roller shaft for a brush roller. Background Art

[0002] A vacuum cleaner is a commonly used cleaning tool. Its operating principle is to push air to the air outlet side of the vacuum cleaner through the high-speed rotation of the internal impeller, so that the air pressure on the air inlet side is lower than the external environmental pressure of the vacuum cleaner, thereby allowing the external air to flow into the body of the vacuum cleaner from the air inlet. The suction head of the vacuum cleaner usually includes a brush roller and a brush placed on the brush roller. When working, the brush roller drives the brush to rotate, rolling up dust and other foreign matter on the cleaned surface and sucking them in. Usually, the brush will be spirally bent at a certain angle, so that it has more contact with the ground during work, the cleaning area is relatively large, and the cleaning force and cleaning efficiency will be improved.

[0003] The existing vacuum cleaner brush roller is divided into a middle-supported structure and a middle-unsupported structure. Among them, the brush roller with a middle-unsupported structure is subjected to greater stress in the middle when rotating at high speed. During repeated use, it will bend and deform, thereby reducing the cleaning effect; the brush slots on the brush roller with a middle-supported structure are all spiral line and single arc transition structures. At the dynamic moment of starting or bearing impact, the intersection of the spiral line and the arc variable cross-section is equivalent to a smooth transition notch, thereby generating stress concentration at this location. During repeated use, it will cause crack initiation and expansion, and eventually fatigue failure. To overcome this shortcoming, the following measures are usually adopted: 1. The spiral line angle will be reduced to reduce the stress concentration coefficient; 2. The material thickness will be increased to prevent the generation of cracks, but reducing the spiral line angle will reduce the cleaning effect and increasing the material thickness will increase the production cost; in addition, the four brush bars at both ends of the roller brush are changed to double brush bars at both ends, and the cleaning force will decrease, so it needs to be improved. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a roller shaft for a brush roller, so as to solve the problem that stress concentration phenomenon is prone to occur in the existing brush roller shaft slot, resulting in fatigue failure.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] The roller shaft for the brush roller comprises a shaft body, wherein the outer peripheral surface of the shaft body comprises at least one spirally extending groove portion for fixing a brush strip, and at least one end portion of the groove portion is a continuous curved transition.

[0007] The end of the groove of the roller adopts a continuous curve transition, and the structure of the single arc transition line at the end of the groove is changed to eliminate the phenomenon of high stress concentration, improve the bearing capacity, and extend the service life of the roller.

[0008] Furthermore, at least one end of the groove is a continuous arc-shaped transition.

[0009] Furthermore, the specific structure of the continuous arc-shaped transition includes three arc transition sections, namely a first arc transition section, a second arc transition section, and a third arc transition section. The two ends of the second arc transition section are connected to the two groove walls of the groove through the first arc transition section and the third arc transition section respectively.

[0010] Furthermore, the second arc segment is an inner arc segment, and the first arc transition segment and the third arc segment are both outer arc segments.

[0011] Furthermore, the arc radius of the first arc transition section is smaller than the arc radius of the second arc transition section, and the arc radius of the third arc transition section is larger than the arc radius of the first arc transition section and smaller than the arc radius of the second arc transition section.

[0012] Furthermore, the first circular arc transition section is tangent to the second circular arc transition section, and the second circular arc transition section is tangent to the third circular arc transition section.

[0013] Furthermore, the arc radius of the first arc transition section is 3-4 mm, the arc radius of the second arc transition section is 19-20 mm, and the arc radius of the third arc transition section is 6-7 mm.

[0014] More preferably, the arc radius of the first arc transition section is 3 mm, the arc radius of the second arc transition section is 19.46 mm, and the arc radius of the third arc transition section is 6 mm.

[0015] Furthermore, the vertical distance between the intersection of the first arc transition section and the second arc transition section and the adjacent groove wall is 2-3 mm, and more preferably, the vertical distance is 2.91 mm.

[0016] Furthermore, the distance between the projection points of the arc vertex of the first arc transition section and the intersection point of the third arc transition section and the groove wall on the groove wall is 11-12 mm, and more preferably, the distance between the projection points of the two on the groove wall is 11.22 mm.

[0017] By analyzing the stress distribution and changes at the end of the groove of the roller during operation, the roller adopts three-arc transition with different radii instead of a single-arc transition structure, thereby reducing the dynamic stress concentration factor, eliminating the phenomenon of high stress concentration, improving the bearing capacity and extending the service life.

[0018] In addition, the three-arc transition structure not only meets the performance requirements of the roller, but also makes processing easier and reduces costs.

[0019] Furthermore, the slot width is 8-9 mm, and more preferably, the slot width is 8.91 mm.

[0020] Beneficial effects of the present invention: The roller adopts a continuous curve to replace the single arc transition structure, thereby reducing the dynamic stress concentration coefficient, thereby eliminating the phenomenon of high stress concentration and improving the bearing capacity of the roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Roller expansion structure diagram of the present invention;

[0022] Figure 2 : Three arc transition structure diagram;

[0023] Figure 3 : The overall structure diagram of the present invention;

[0024] Figure 4 : Single arc transition structure diagram on the market;

[0025] Figure 5 : Stress state diagram of the entire cross section of the brush roller;

[0026] Figure 6 : Stress level diagram of the brush roller when the spiral section is uniformly stressed;

[0027] Figure 7 : Stress level diagram of the brush roller spiral section under dynamic instantaneous stress state;

[0028] Figure 8 : Stress level diagram of the brush roller spiral line and arc variable cross-section under dynamic instantaneous stress state;

[0029] In the figure: 1, shaft body; 2, groove; 3, three-arc transition section; 4, mounting hole; 31, first arc transition section; 32, second arc transition section; 33, third arc transition section. DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are further described below in conjunction with the accompanying drawings to make the technical solutions of the present invention easier to understand and grasp.

[0031] Figure 4 The groove structure of a general roller on the market is shown. The end of the roller adopts a single arc transition structure. During the working process, especially at the dynamic moment of starting or bearing impact, the intersection of the spiral line and the arc section is equivalent to a smooth transition notch, which generates stress concentration at this point. During repeated use, it will cause crack initiation and expansion, and eventually fatigue failure, as described below:

[0032] 1. If Figure 5 As shown, assuming that the brush roller is subjected to a 60-pound uniform load, when its entire cross section is under stress,

[0033] Stress level P = F / S = 60*0.4S4*9.8 / 12S*1 = 2.14MPa;

[0034] Refer to the mechanical properties of 202 stainless steel and 304 stainless steel, where the yield strength of 202 stainless steel is ≥275, and the yield strength of 304 stainless steel is σ0.2=205MPa. Figure 5 The stress level when the entire cross section is under stress is much lower than the yield strength of the two materials, and fatigue failure will not occur.

[0035] 2. The stress level when the spiral section is uniformly stressed. The spiral section is uniformly stressed as follows: Figure 6 As shown, axial stress: P = Fsinα / S = 0.55MPa, normal stress: P = Fcosα / S = = 1.50MPa, Figure 6 The medium stress level is also much lower than the yield strength of both materials and fatigue failure will not occur.

[0036] 3. The stress level of the spiral section when it is subjected to dynamic instantaneous stress. Figure 7 As shown in the figure, at the dynamic instant of starting or bearing impact, not all the spiral lines of the spiral section are stressed at the same time. After simplified load calculation, the length of the instantaneous stressed section is only about 5-10mm, and the stress P=F / S=26.7-53.4MPa. If the part bearing the dynamic load is located in the middle of the brush, the stress level of the spiral section is also lower than the yield strength of the two materials, and fatigue damage generally does not occur.

[0037] 4. The stress level of the helix and arc variable cross section under dynamic instantaneous stress state. The stress of the helix and arc variable cross section is as follows: Figure 8 As shown in the figure, at the dynamic moment of starting or bearing impact, the intersection of the spiral line and the arc variable cross section is equivalent to a smooth transition notch with a curvature radius of R, which produces stress concentration. The stress concentration coefficient K is about 1.5-2, making the instantaneous force at this point 1.5-2 times that of the spiral cross section in the middle of the brush.

[0038] Stress P = K*F / S = 40.1-106.8MPa. Therefore, at the dynamic moment of starting or bearing impact, the stress at the intersection of the spiral line and the arc variable cross-section can reach up to 106.8MPa due to stress concentration, which is half of the yield strength of the two materials and has the possibility of fatigue failure.

[0039] 5. The stress level of the sharp notch of the spiral line and the arc variable cross-section in the dynamic instantaneous stress state. When the sharp notch of the spiral line and the arc variable cross-section is stressed, at the dynamic moment of starting or bearing the impact, there is a smooth transition notch effect with a curvature radius of R at the intersection of the spiral line and the arc variable cross-section, which produces stress concentration. If there is such a sharp notch at the transition point, it will produce a stress concentration superposition effect. Figure 5The stress concentration coefficient K of the sharp notch is about 2-4. Therefore, the superimposed stress coefficient at the arc can reach 2.5-5, making the instantaneous force there 2.5-5 times that of the spiral section in the middle of the brush.

[0040] Stress P = K*F / S = 66.75-267MPa

[0041] In addition to causing stress and strain concentration, the notch effect also changes the stress state in front of the notch, changing the stress from the original unidirectional tension to two-way or three-way tension: although this notch strengthening phenomenon increases the strength of the plastic material, the notch constrains the plastic deformation of the material, reducing the plasticity of the material. Therefore, the notch also strengthens the plastic material.

[0042] Therefore, at the dynamic moment of starting or bearing impact, if there is a sharp notch at the intersection of the spiral line and the arc variable cross-section, due to stress concentration, the stress can reach 267MPa or even higher, which has exceeded the yield strength of the two materials and there is a great risk of fatigue failure.

[0043] Several measures are as follows:

[0044] (1) Change the angle of the helix to make it smaller.

[0045] (2) Change the transition design between the helix and the arc to increase the arc R or make it move away from the helix.

[0046] (3) Eliminate sharp notches.

[0047] (4) Increase the material thickness appropriately.

[0048] (5) Replace with a material with higher yield strength.

[0049] However, there are the following disadvantages:

[0050] 1. The spiral angle will be reduced to reduce the stress concentration factor; 2. The material thickness will be increased to prevent cracks from occurring, but reducing the spiral angle will reduce the cleaning effect and increasing the material thickness will increase the production cost; in addition, the cleaning power will be reduced by changing the four brush bars at both ends of the roller brush to double brush bars at both ends.

[0051] In view of the above problems, the roller is redesigned and a continuous curve structure is adopted instead of a single arc transition structure, so that the arc R is enlarged and away from the spiral line to reduce the dynamic stress concentration coefficient, thereby eliminating the phenomenon of high stress concentration and improving the bearing capacity. This will be explained below with diagrams and embodiments.

[0052] Figure 1 , Figure 2 , Figure 3 The specific structure of the roller shaft for the brush roller is shown. In this embodiment, three arc transition sections are used instead of a single arc transition structure. Figure 1, Figure 3 As shown, the shaft body of the roller shaft is a cylinder, and a mounting hole is provided in the middle to install a support mechanism, etc. In this embodiment, a four-groove structure is adopted, and the outer peripheral surface of the shaft body contains four spirally extending grooves, such as Figure 2 As shown, the head end of the groove portion adopts a three-arc transition section structure, and the tail end opening extends to the roller axis boundary, two by two in a group, and the two grooves in each group are mirror-symmetrical with the center line formed by the mounting hole, and are spaced apart from each other;

[0053] The three arc transition sections are respectively a first arc transition section, a second arc transition section, and a third arc transition section, and two ends of the second arc transition section are connected to two groove walls of the groove portion through the first arc transition section and the third arc transition section respectively;

[0054] The second arc segment is an inner arc segment, and the first arc transition segment and the third arc segment are both outer arc segments;

[0055] The roller shaft has a length of 113.4 mm, a diameter of 12.5 mm, a wall thickness of 0.39 mm, and a three-arc transition section structure. Figure 2 As shown, the first arc transition section is tangent to the second arc transition section, and the second arc transition section is tangent to the third arc transition section. In this embodiment, the groove width is 8.91 mm, the arc radius of the first arc transition section is 3 mm, the arc radius of the second arc transition section is 19.46 mm, and the arc radius of the third arc transition section is 6 mm. The arc radius of the first arc transition section is smaller than the arc radius of the second arc transition section, and the arc radius of the third arc transition section is larger than the arc radius of the first arc transition section and smaller than the arc radius of the second arc transition section.

[0056] The vertical distance between the intersection of the first arc transition section and the second arc transition section and the adjacent groove wall is 2.91 mm, and the distance between the projection points of the arc vertex of the first arc transition section and the intersection of the third arc transition section and the groove wall on the groove wall is 11.22 mm.

[0057] In this embodiment, the four-groove structure of the roller shaft is maintained, and brush strips are installed through the grooves to form a four-brush strip structure at both ends. However, according to the stress change at the groove end, the structure of the groove is redesigned and optimized, wherein the groove width is 8.91mm, the arc radius of the first arc transition section is 3mm, the arc radius of the second arc transition section is 19.46mm, the arc radius of the third arc transition section is 6mm, and the vertical distance between the intersection of the first arc transition section and the second arc transition section and the adjacent groove wall is 2.91mm, and the distance between the projection points of the arc vertex of the first arc transition section and the intersection of the third arc transition section and the groove wall on the groove wall is 11.22mm.

[0058] The redesigned roller was tested for continuous operation, with four brushes installed for 500 hours. No fatigue cracking occurred at the transition points of the three arcs. Other similar products had a shorter lifespan than this product when tested under the same conditions.

[0059] Of course, the above are only specific application examples of the present invention and do not constitute any limitation on the protection scope of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement falls within the protection scope of the present invention.

Claims

1. A roller shaft for a brush roller, comprising a shaft body, wherein the outer peripheral surface of the shaft body comprises at least one spirally extending groove for fixing a brush strip, wherein: At least one end of the groove is a continuous curved transition; At least one end of the groove is a continuous arc-shaped transition; The specific structure of the continuous arc transition includes three arc transition sections, namely a first arc transition section, a second arc transition section, and a third arc transition section, and two ends of the second arc transition section are connected to two groove walls of the groove portion through the first arc transition section and the third arc transition section respectively; The second arc segment is an inner arc segment, and the first arc transition segment and the third arc segment are both outer arc segments; The arc radius of the first arc transition section is smaller than the arc radius of the second arc transition section, and the arc radius of the third arc transition section is larger than the arc radius of the first arc transition section and smaller than the arc radius of the second arc transition section; The first circular arc transition section is tangent to the second circular arc transition section, and the second circular arc transition section is tangent to the third circular arc transition section; The arc radius of the first arc transition section is 3-4 mm, the arc radius of the second arc transition section is 19-20 mm, and the arc radius of the third arc transition section is 6-7 mm; The vertical distance between the intersection of the first arc transition section and the second arc transition section and the adjacent groove wall is 2-3 mm.

2. The roller shaft for the brush roller according to claim 1, characterized in that: The distance between the projection points of the arc vertex of the first arc transition section and the intersection point of the third arc transition section and the groove wall on the groove wall is 11-12 mm.

3. The roller shaft for the brush roller according to claim 1, characterized in that: The groove opening width is 8-9 mm.

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