CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase entry of International Application No. PCT/CN2016/108055, filed Nov. 30, 2016, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a screwdriver head, and in particular, to a screwdriver head with high rigidity and high abrasive resistance in a head portion as well as high tenacity in other portions by forming an alloyed layer on the surface of the head portion of the screwdriver head through laser surface alloying treatment. The present invention further relates to a method for manufacturing the screwdriver head.

DESCRIPTION OF THE PRIOR ART

A screwdriver is a tool for screwing or unscrewing screws. According to its type and configuration, the screwdriver can be categorized into an ordinary integrated screwdriver and a combined screwdriver, in which a handle of the ordinary screwdriver is inseparably integrated with its screwdriver head; a handle of the combined screwdriver can be combined with or separated from its screwdriver head. The screwdriver head is provided with a head portion for being inserted into a slot of a screw head and a basal body for supporting the head portion. Generally, the head portion of the screwdriver head commonly has a slotted shape, a cross shape, a star shape, an intersected shape, a square shape and a hexagonal shape.

Based on the difference in function, the head portion and basal body of the screwdriver head have different structural characteristics. In order to overcome a torque generated when screwing the screw, the basal body of the screwdriver head needs sufficient tenacity and the head portion inserted into the slot of the screw head needs high rigidity and high abrasive resistance. A conventional screwdriver head is made of an integral material, and in other words, the head portion and the basal body of the screwdriver head are made into required forms by a single material, and then a heat-treating process is conducted on the whole, thereby finishing the manufacture of the conventional screwdriver head. For the screwdriver head made of an integral material, the requirements of high rigidity and high abrasive resistance in the head portion of the screwdriver head and of high tenacity in other portions are not usually satisfied at the same time.

Therefore, one of the goals the producers and the developers of the screwdriver head keep on trying for is to realize high rigidity and high abrasive resistance in the head portion and high tenacity in other portions at the same time.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a screwdriver head with high rigidity and high abrasive resistance in the head portion as well as high tenacity in other portions and with a long service life, as well as a method for manufacturing the screwdriver head.

In order to solve the above technical problem, the present invention provides a method for manufacturing a screwdriver head, comprising:

providing a screwdriver head made of a first metal material, wherein the screwdriver head comprises a head portion for being inserted into a slot of a screw head and a basal body for supporting the head portion;

preparing alloying coating;

coating the alloying coating on the surface of the head portion of the screwdriver head;

conducting laser surface alloying treatment on the surface of the head portion of the screwdriver head coated with the alloying coating, and forming an alloyed layer on the surface of the head portion of the screwdriver head; and

conducting low temperature tempering treatment on the screwdriver head after the laser surface alloying treatment.

Further, the first metal material comprises any one of spring steel, alloy structural steel and tool steel.

Further, the alloying coating contains a large quantity of alloy elements such as W, Mo, Ti, V and Al. During the laser surface alloying treatment conducted on the surface of the head portion of the screwdriver head, a laser beam first melts the alloying coating containing the alloy elements such as W, Mo, Ti, V and Al and a surface layer of the head portion of the screwdriver head close to the coating, and the alloying coating and its alloy elements fuse into the surface layer of the head portion of the screwdriver to form an alloyed layer, that is, the alloy elements in the alloyed layer are from the alloying coating.

As a further improvement of the manufacturing method of the present invention, the alloying coating is coated on a surface of a position at which the head portion of the screwdriver head contacts with the slot of the screw head.

Further, by mass percentage, the alloying coating contains 5˜20 of C, 2˜18 of B, 2˜38 of Si, 0.2˜6 of N, 0.5˜15 of O, 0.3˜6 of Al, 2˜10 of Mo, 2˜10 of V, 2˜20 of W and 2˜20 of Ti.

Preferably, by mass percentage, the alloying coating contains 5.5˜17 of C, 2.7˜16.6 of B, 2.3˜29.6 of Si, 0.22˜4.9 of N, 0.56˜13.7 of O, 0.33˜5.6 of Al, 2.7˜9.8 of Mo, 2.7˜9.8 of V, 2.7˜19.8 of W and 2.7˜19.8 of Ti.

Further, the process parameters for the laser surface alloying treatment comprises: 200˜3000 W of laser power, 0.2˜3 mm of spot diameter, 5˜80 mm/min of laser scanning speed, and 0.05˜1 mm of the thickness of the alloying coating.

Preferably, the process parameters for the laser surface alloying treatment comprises: 280˜2600 W of laser power, 0.2˜2.8 mm of spot diameter, 5.5˜75 mm/min of laser scanning speed, and 0.07˜1 mm of the thickness of the alloying coating.

Further, a wave length of the laser used in the laser surface alloying treatment is no greater than 10.6 um, and the power of the laser is greater than 2000 W.

Preferably, the wave length of the laser used in the laser surface alloying treatment is no greater than 1.06 um, and the power of the laser is greater than 2000 W.

Further, the low temperature tempering treatment comprises heating the screwdriver head after the laser surface alloying treatment to 160 to 180° C., and conducting heat preservation for 1 hour.

Preferably, the low temperature tempering treatment comprises heating the screwdriver head after the laser surface alloying treatment to 180° C. by using a low temperature tempering furnace with gas cycling, and conducting heat preservation for 1 hour. The low temperature tempering furnace enables the distribution of temperature inside the tempering furnace to be more uniform by means of the gas cycling.

Another aspect of the present invention provides a screwdriver head which is made of a first metal material, the screwdriver head at least comprising: a head portion for being inserted into a slot of a screw head and a basal body for supporting the head portion, and an alloyed layer formed on the surface of the head portion.

The alloyed layer is formed by alloying coating coated on the surface of the head portion at least containing one or more alloy elements of C, B, Si, N, O, Al, Mo, V, W and Ti by conducting laser surface alloying treatment.

The alloyed layer has a cryptocrystalline martensite structure with tiny crystal particle size, and the alloyed layer has nearly no defects of segregation, microcrack, air hole and slag inclusion.

As a preferred structure of the screwdriver head of the present invention, the alloyed layer is formed to the position at which the head portion contacts with the slot of the screw head.

Further, the first metal material comprises any one of spring steel, alloy structural steel and tool steel.

Further, the depth of the alloyed layer is no less than 0.05 mm.

Further, compared with the rigidity of the basal body, the rigidity of the alloyed layer is increased by greater than 2 HRC.

Further, a heat affected zone is provided between the alloyed layer and the basal body, and the width of the heat affected zone is no greater than 1.0 mm.

Further, compared with the rigidity of the basal body, the rigidity of the heat affected zone is decreased, with a decreased magnitude no greater than 8 HRC.

Another aspect of the present invention provides a screwdriver which comprises the screwdriver head made by the above method for manufacturing the screwdriver head, or the above screwdriver head and a handle which is used for connecting the screwdriver head.

Further, the handle of the above screwdriver is inseparably integrated with the screwdriver head.

Further, the handle of the above screwdriver is provided with a combined hole, into or from which the basal body of the screwdriver head can be inserted or withdrawn.

Further, the head portion, for being inserted into the slot of the screw head, of the above screwdriver head has any one of a slotted shape, a cross shape, a star shape, an intersected shape, a square shape and a hexagonal shape.

In the method for manufacturing a screwdriver head proposed by the present invention and the screwdriver head made by the manufacturing method, the alloyed layer is formed at the head portion of the screwdriver head by a surface modification process of the laser surface alloying treatment, which makes the head portion have high rigidity and high abrasive resistance and other positions have high tenacity, thereby enabling the screwdriver head made by the method for manufacturing a screwdriver head proposed by the present invention to have a longer service life.

The alloyed layer of the screwdriver head proposed by the present invention is formed by alloying coating coated on the surface of the head portion at least containing one or more alloy elements of C, B, Si, N, O, Al, Mo, V, W and Ti by conducting laser surface alloying treatment. The alloyed layer has a cryptocrystalline martensite structure with tiny crystal particle size, which further improves the abrasive resistance of the head portion. Compared with the conventional screwdriver head which is not produced by the method for manufacturing a screwdriver head proposed by the present invention, the front and side of the head portion of the screwdriver head produced by the method for manufacturing a screwdriver head proposed by the present invention are not abraded noticeably after this screwdriver head is in practice used to manually screw 500 tapping screws with a size of 3.5*50 mm on a pine board, which obviously prolongs the service life of the screwdriver head.

The technical conception and specific embodiments of the present invention will be further illustrated in detail below in conjunction with the accompanying drawings.

