Ultrasound-assisting quenching process and device for performing the same

Abstract

An ultrasound-assisting quenching process includes: S1) connect the workpiece with the ultrasonic unit tightly; S2) heat the workpiece to the quenching temperature and then hold for a period of time; S3) start the ultrasonic unit, then the ultrasound energy can be injected into the workpiece directly; and S4) put the workpiece into the coolant quickly to make the workpiece to be quenched. The device for this process mainly includes the ultrasonic unit and a heating unit. This invention inputs the ultrasound energy into the workpiece during the quenching process. Under the action of the ultrasound, the grain size of the workpiece after quenching process will be much smaller compared with the conventional quenching process. Therefore, the ultrasound-assisting quenching process can improve the strength and plasticity of the material, and extend the life of the workpiece.

Claims

1. An ultrasound-assisting quenching process, comprising: S1) connecting a workpiece with an ultrasonic unit; S2) heating the workpiece to a quenching temperature and then holding for a period of time; S3) starting the ultrasonic unit, injecting ultrasound energy into the workpiece directly, wherein a relationship between a frequency of the ultrasound generated by the ultrasonic unit and a self-frequency of the workpiece is 500 Hzf.sub.1f.sub.2500 Hz, where f.sub.1 is the frequency of the ultrasound, and f.sub.2 is the self-resonant frequency of the workpiece; S4) putting the workpiece into a coolant quickly to allow the workpiece to be quenched.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The present invention will become more fully understood from the detailed description given here in below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein:

(2) FIG. 1 is a schematic view of a device that can perform an ultrasound-assisting quenching process.

DETAILED DESCRIPTION

(3) In order to clearly understand about the process characteristics, aim and the effects of this invention, here are some preferential embodiments to express this process and device based on the FIGURE.

(4) The invention provides a novel ultrasound-assisting quenching process, which include the following steps: S1) connect the workpiece with the ultrasonic unit tightly. There are lots of ways can be chosen, such as threaded connection, buckled connection and so on. In this case, threaded connection is selected since it can be kept tight and be operated easily. S2) heat the workpiece to the quenching temperature and then hold for a period of time. The quenching temperature and holding time for this process are the same as that in the conventional quenching process. S3) start the ultrasonic unit, then the ultrasound energy can be injected into the workpiece directly. To ensure the workpiece can be resonated under the effect of ultrasound and make the internal atoms of the workpiece to be vibrated with a high frequency, the frequency of the ultrasound f.sub.1 should be close to the self-resonant frequency of the workpiece f.sub.2. In this invention, 500 Hzf.sub.1f.sub.2500 Hz, most preferably, f.sub.1 is equal to f.sub.2. In some embodiments, for a workpiece made of a particular type of material, the size and the shape of the workpiece can be changed to helps adjust the self-resonant frequency of the workpiece f.sub.2, thereby allowing the self-resonant frequency f.sub.2 of the workpiece to be close to the frequency f.sub.1 of the ultrasound.

(5) The temperature of workpiece will be reduced and the self-resonant frequency can also be changed in a small range during quenching process. So, a frequency tracker is required for the ultrasonic unit to ensure continuous resonance when frequency changes because of temperature changing. Therefore, the internal atoms of the workpiece can be resonated in a high frequency during the whole quenching process. S4) put the workpiece into the coolant quickly to make the workpiece to be quenched. During the whole quenching process, the ultrasonic unit should be kept on. The coolant, cooling temperature and cooling time are the same as that in the conventional quenching process.

(6) Because ultrasound energy is injected into the workpiece, the internal atoms of the workpiece will be resonated in a high frequency, which cause the lattice of the martensite phase and austenite phase to be distorted and generate the elastic distortion energy. All of these can improve the driving force from austenite phase to martensite phase, and then promote the transformation from austenite phase to martensite phase, decrease retained austenite and refine the martensite phase. It can not only increase the hardness and strength of the workpiece, but also increase the plasticity and extend the service life of the workpiece.

(7) FIG. 1 illustrates a device used for the ultrasound-assisting quenching process, which includes two units: one is the heating unit (5) used to heat the workpiece (4) and hold the temperature for a period of time, and the other is the ultrasonic unit. Connect the workpiece (4) with the ultrasonic unit tightly. There are lots of ways to be selected to connect these two parts, for example threaded connection, buckled connection. Threaded connection is the first choose since it can be kept tight and be operated easily

(8) In this invention, ultrasound energy is directly injected into the workpiece (4) and then quenched. With the assistance of the ultrasound energy, refined crystalline grain can be obtained, which can not only increase the hardness and strength of the workpiece (4) but also increase the plasticity and extend the life of the workpiece. To ensure the workpiece (4) can be resonated under the effect of ultrasound and make the internal atoms of the workpiece (4) to be vibrated in high frequency, the frequency of the ultrasound f.sub.1 should be close to the self-resonant frequency of the workpiece (4) f.sub.2. In this invention, 500 Hzf.sub.1f.sub.2500 Hz, most preferably, f.sub.1 is equal to f.sub.2.

(9) The temperature of workpiece (4) will be reduced and the self-resonant frequency can also be changed in a small range during quenching process. A frequency tracker is used in ultrasound generator (1) to ensure continuous resonant when frequency changes because of temperature changing. During the whole quenching process, the internal atoms of the workpiece (4) can be resonated in a high frequency all the time.

(10) What is more, the ultrasonic unit includes ultrasound generator (1), transducer (2) and amplifier (3). The ultrasonic vibration generator (1) can generate high-frequency impulse electrical signal and then the signal will be transferred into transducer (2). Transducer (2) can change high-frequency impulse electrical signal into high-frequency mechanical vibration, and amplifier (3) can enlarge the mechanical vibration to obtain homogeneous ultrasound. Connect the workpiece (4) with amplifier (3) tightly, so the ultrasound energy can be directly injected into the workpiece (4).

(11) The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.