日期:2024-09-20 14:57
瀏覽次數(shù):0
摘要:<p class="MsoNormal" style="white-space:normal;text-align:center;">
<span style="font-size:14px;">粉末冶金零件整形模具的深冷處理工藝的研究</span>
</p>
<p class="p" style="white-space:normal;">
<span style="font-size:14px;"> [摘要]分析了不同深冷工藝處理的整形芯棒壽命和磨損形貌,探討了整形模具的磨損機理和*佳冷處理工藝。 </span><br />
<span style="font-size:14px;">粉末冶金零件由于其固有的優(yōu)點,而在機械等行業(yè)被越來越廣泛應(yīng)用。粉末冶金零件的制作工藝一般是這樣的:粉體壓制成型-高溫澆結(jié)-整形。經(jīng)整形后的粉末冶金零件只要稍微機加工一下就直接裝備,因此,對經(jīng)整形后的零件尺寸的公差有嚴格要求,為了保證粉末冶金零件尺寸要求,對整形模具陰模和芯棒的尺寸公差的要求也就比較嚴格,如某種襯套的整形芯棒尺寸要求Ф20+0.025。陰模和芯棒在整形過程中受到很大的擠壓力作用,工況條件十分惡劣,很容易由于嚴重磨損引起尺寸超差而報廢。因此,提高粉末冶金零件整形模具的耐磨性,從而提高整形模具的壽命對粉末冶金零件質(zhì)量和降低粉末冶金零件生產(chǎn)成本都有十分重要意義。本文擬通過對粉末冶金零件整形芯棒的深冷處理,來探討出提高粉末冶金零件整形模具壽命的深冷處理工藝。 </span><br />
<span style="font-size:14px;">1.試驗方法 </span><br />
<span style="font-size:14px;">從某粉末冶金廠取一批機加工好后的132襯套整形芯棒,芯棒材料為GCr15。芯棒經(jīng)正常的淬火+150℃低溫回火后,盡快進行深冷處理,深冷溫度分別有-100℃、-120℃、-140℃、-160℃和-196℃五種,保溫時間分別有1h、2h、4h、和8h 4個時間。深冷處理后的模具都經(jīng)低于150℃的溫度回火,保溫時間均為1h,并分別測定其硬度。把經(jīng)深冷處理的芯棒與同批熱處理而未經(jīng)深冷處理的芯棒分別裝機測定其壽命,并用低倍放大鏡分別觀察處理工藝不同的模具的磨損形貌。 </span><br />
<span style="font-size:14px;">2.試驗結(jié)果及分析 </span><br />
<span style="font-size:14px;">2.1試驗結(jié)果 </span><br />
<span style="font-size:14px;">表1 芯棒經(jīng)不同處理工藝的壽命及硬度</span>
</p>
<table class="MsoNormalTable" align="center" style="width:809px;">
<tbody>
<tr>
<td width="125" valign="center" style="border:0.75pt outset windowtext;">
<p class="MsoNormal" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:12pt;"><br />
</span><span style="font-family:宋體;font-size:14px;">深冷處理溫度 </span><span style="font-family:宋體;font-size:12pt;"><br />
</span><span style="font-family:宋體;font-size:14px;"> (℃)</span><span style="font-family:"Times New Roman";font-size:10.5pt;"></span>
</p>
</td>
<td width="175" valign="top" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">深冷處理保溫時間 </span><span style="font-family:宋體;font-size:10pt;"><br />
</span><span style="font-family:宋體;font-size:14px;"> (h)</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">平均使用壽命 </span><span style="font-family:宋體;font-size:10pt;"><br />
</span><span style="font-family:宋體;font-size:14px;">(整形零件個數(shù))</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">平均硬度 </span><span style="font-family:宋體;font-size:10pt;"><br />
</span><span style="font-family:宋體;font-size:14px;">(HPC)</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" rowspan="4" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">-100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">1</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">3800</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">60.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">2</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">60.6</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4300</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">8</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4500</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" rowspan="4" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">-120</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">1</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4400</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">60.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">2</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4800</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;"> </span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;"> </span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5300</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" rowspan="4" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">-140</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">1</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5200</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">2</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5500</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5800</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">61.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">8</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">6100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" rowspan="4" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">-160</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">1</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">5900</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">2</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">6600</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">6900</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">8</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">7100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" rowspan="4" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">-196</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">1</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">6300</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">2</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">6800</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">4</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">7100</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">8</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">7200</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">62</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
<tr>
<td width="125" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">未經(jīng)深冷處理</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="175" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;"> </span>
</p>
</td>
<td width="168" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">3000</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
<td width="156" valign="center" style="border:0.75pt outset windowtext;">
<p class="p" style="margin-left:0pt;text-align:center;">
<span style="font-family:宋體;font-size:14px;">60.5</span><span style="font-family:宋體;font-size:10pt;"></span>
</p>
</td>
</tr>
</tbody>
</table>
<p class="MsoNormal" style="white-space:normal;">
<span style="font-size:14px;">由表</span><span style="font-size:14px;">1</span><span style="font-size:14px;">可以看出,粉末冶金零件整形芯棒經(jīng)深冷處理后,使用壽命明顯提高。深冷溫度越低、保溫時間越長,模具失效前整形的零件個數(shù)也就越多,即模具的使用壽命也就越長。但保溫時間相同情況下,</span><span style="font-size:14px;">-160℃</span><span style="font-size:14px;">和</span><span style="font-size:14px;">-196℃</span><span style="font-size:14px;">兩種深冷處理溫度整形芯棒的壽命相差不大。在相同的處理溫度下,保溫時間超過兩小時,模具壽命發(fā)生跳躍式上升,而后隨著保溫時間的延長模具壽命平緩上升。</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">2.2</span><span style="font-size:14px;">試驗結(jié)果分析</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">觀察失效整形模具表面發(fā)現(xiàn),模具表面布滿剝落坑和很多細小犁溝。這是由于模具在整形過程中,被整形的粉末冶金零件</span><span style="font-size:14px;">132</span><span style="font-size:14px;">襯套的粉體密度較高,達</span><span style="font-size:14px;">7.0g/cm3</span><span style="font-size:14px;">,燒結(jié)后硬度也較高,芯棒和陰模在整形過程中受到很大的擠壓力,模具在反復(fù)擠壓下,在模具亞表層殘余奧氏體處發(fā)生反復(fù)變形,產(chǎn)生位錯塞積,而萌生裂紋,在反復(fù)擠壓過程中裂紋擴展,直至表面而剝落,形成嚴重的剝落坑</span><span style="font-size:14px;">(1)</span><span style="font-size:14px;">。另外粉體中存在的雜質(zhì)</span><span style="font-size:14px;">——</span><span style="font-size:14px;">多種硬質(zhì)相粒子,在模具整形過程中在模具表面產(chǎn)生犁削,使模具表面布滿犁溝,由于雜質(zhì)粒子較小,故形成的犁溝較淺。芯棒由剝落和犁削共同作用下,產(chǎn)生尺寸超差而報廢。</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">GCr15</span><span style="font-size:14px;">模具鋼制作的芯棒在深冷處理過程中組織結(jié)構(gòu)發(fā)生如下變化</span><span style="font-size:14px;">(2)(3)</span><span style="font-size:14px;">,殘余奧氏體量減少。殘余奧氏體中合金元素,特別是碳元素起著強化殘余奧氏體的作用,因而需要較多的能量才能促使剪切機理來產(chǎn)生馬氏體,深冷處理就是利用過冷度來增加馬氏體轉(zhuǎn)變的驅(qū)動力,隨著深冷溫度降低,過冷度增加,馬氏體轉(zhuǎn)變越完全。在冷卻過程中殘余奧氏體向馬氏體的轉(zhuǎn)變速度,不取決與時間,而與過冷度有關(guān),即殘余奧氏體量只與深冷溫度有關(guān)。另外,深冷處理還可以析出細小碳化物,細化組織結(jié)構(gòu)。</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">深冷處理減少了殘余奧氏體量,增加了芯棒在擠壓過程中在亞表層萌生裂紋的難度,同時由于殘余奧氏體量減少以及細小碳化物析出和組織細化,使犁削難度增加。因此,芯棒經(jīng)深冷處理后,增加了抗疲勞磨損和磨粒磨損的能力,從而提高了芯棒壽命。如果深冷處理溫度較高</span><span style="font-size:14px;">(</span><span style="font-size:14px;">高于</span><span style="font-size:14px;">-160℃)</span><span style="font-size:14px;">,過冷度較小,殘余奧氏體向馬氏體的轉(zhuǎn)變的能量不足,殘余奧氏體量較多,表現(xiàn)在模具硬度幾乎不變,模具壽命提高不多。在較低溫度下深冷處理,只要保溫時間足以使芯棒冷透</span><span style="font-size:14px;">(</span><span style="font-size:14px;">不小于</span><span style="font-size:14px;">2h)</span><span style="font-size:14px;">,殘余奧氏體向馬氏體的轉(zhuǎn)變就較為完全,但馬氏體中析出的細小碳化物的量隨著保溫時間的延長而緩慢增加。因此,模具壽命也隨保溫時間延長而緩慢增加。如果考慮到隨著保溫時間延長,模具深冷處理的成本也增大,那么取保溫時間為</span><span style="font-size:14px;">2</span><span style="font-size:14px;">~</span><span style="font-size:14px;">4h</span><span style="font-size:14px;">*適宜。</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">3</span><span style="font-size:14px;">.結(jié)語</span><span style="font-size:14px;"> </span><br />
<span style="font-size:14px;">粉末冶金零件整形模具的破壞機理為疲勞磨損和磨粒磨損。模具經(jīng)深冷處理可以大幅度提高其壽命。深冷溫度以</span><span style="font-size:14px;">-160℃</span><span style="font-size:14px;">~</span><span style="font-size:14px;">-196℃</span><span style="font-size:14px;">為*佳,保溫時間越長模具壽命越高,但從成本和壽命兩方面綜合考慮,取</span><span style="font-size:14px;">2</span><span style="font-size:14px;">~</span><span style="font-size:14px;">4h</span><span style="font-size:14px;">為宜。</span>
</p>
<p class="MsoNormal" style="white-space:normal;">
<span style="font-size:14px;"> </span>
</p>
粉末冶金零件整形模具的深冷處理工藝的研究
[摘要]分析了不同深冷工藝處理的整形芯棒壽命和磨損形貌,探討了整形模具的磨損機理和*佳冷處理工藝。
粉末冶金零件由于其固有的優(yōu)點,而在機械等行業(yè)被越來越廣泛應(yīng)用。粉末冶金零件的制作工藝一般是這樣的:粉體壓制成型-高溫澆結(jié)-整形。經(jīng)整形后的粉末冶金零件只要稍微機加工一下就直接裝備,因此,對經(jīng)整形后的零件尺寸的公差有嚴格要求,為了保證粉末冶金零件尺寸要求,對整形模具陰模和芯棒的尺寸公差的要求也就比較嚴格,如某種襯套的整形芯棒尺寸要求Ф20+0.025。陰模和芯棒在整形過程中受到很大的擠壓力作用,工況條件十分惡劣,很容易由于嚴重磨損引起尺寸超差而報廢。因此,提高粉末冶金零件整形模具的耐磨性,從而提高整形模具的壽命對粉末冶金零件質(zhì)量和降低粉末冶金零件生產(chǎn)成本都有十分重要意義。本文擬通過對粉末冶金零件整形芯棒的深冷處理,來探討出提高粉末冶金零件整形模具壽命的深冷處理工藝。
1.試驗方法
從某粉末冶金廠取一批機加工好后的132襯套整形芯棒,芯棒材料為GCr15。芯棒經(jīng)正常的淬火+150℃低溫回火后,盡快進行深冷處理,深冷溫度分別有-100℃、-120℃、-140℃、-160℃和-196℃五種,保溫時間分別有1h、2h、4h、和8h 4個時間。深冷處理后的模具都經(jīng)低于150℃的溫度回火,保溫時間均為1h,并分別測定其硬度。把經(jīng)深冷處理的芯棒與同批熱處理而未經(jīng)深冷處理的芯棒分別裝機測定其壽命,并用低倍放大鏡分別觀察處理工藝不同的模具的磨損形貌。
2.試驗結(jié)果及分析
2.1試驗結(jié)果
表1 芯棒經(jīng)不同處理工藝的壽命及硬度
深冷處理溫度
(℃)
|
深冷處理保溫時間
(h)
|
平均使用壽命
(整形零件個數(shù))
|
平均硬度
(HPC)
|
-100
|
1
|
3800
|
60.5
|
2
|
4100
|
60.6
|
4
|
4300
|
61
|
8
|
4500
|
61.5
|
-120
|
1
|
4400
|
60.5
|
2
|
4800
|
61
|
|
5100
|
61
|
|
5300
|
61.5
|
-140
|
1
|
5200
|
61
|
2
|
5500
|
61.5
|
4
|
5800
|
61.5
|
8
|
6100
|
62
|
-160
|
1
|
5900
|
62
|
2
|
6600
|
62
|
4
|
6900
|
62
|
8
|
7100
|
62
|
-196
|
1
|
6300
|
62
|
2
|
6800
|
62
|
4
|
7100
|
62
|
8
|
7200
|
62
|
未經(jīng)深冷處理
|
|
3000
|
60.5
|
由表1可以看出,粉末冶金零件整形芯棒經(jīng)深冷處理后,使用壽命明顯提高。深冷溫度越低、保溫時間越長,模具失效前整形的零件個數(shù)也就越多,即模具的使用壽命也就越長。但保溫時間相同情況下,-160℃和-196℃兩種深冷處理溫度整形芯棒的壽命相差不大。在相同的處理溫度下,保溫時間超過兩小時,模具壽命發(fā)生跳躍式上升,而后隨著保溫時間的延長模具壽命平緩上升。
2.2試驗結(jié)果分析
觀察失效整形模具表面發(fā)現(xiàn),模具表面布滿剝落坑和很多細小犁溝。這是由于模具在整形過程中,被整形的粉末冶金零件132襯套的粉體密度較高,達7.0g/cm3,燒結(jié)后硬度也較高,芯棒和陰模在整形過程中受到很大的擠壓力,模具在反復(fù)擠壓下,在模具亞表層殘余奧氏體處發(fā)生反復(fù)變形,產(chǎn)生位錯塞積,而萌生裂紋,在反復(fù)擠壓過程中裂紋擴展,直至表面而剝落,形成嚴重的剝落坑(1)。另外粉體中存在的雜質(zhì)——多種硬質(zhì)相粒子,在模具整形過程中在模具表面產(chǎn)生犁削,使模具表面布滿犁溝,由于雜質(zhì)粒子較小,故形成的犁溝較淺。芯棒由剝落和犁削共同作用下,產(chǎn)生尺寸超差而報廢。
GCr15模具鋼制作的芯棒在深冷處理過程中組織結(jié)構(gòu)發(fā)生如下變化(2)(3),殘余奧氏體量減少。殘余奧氏體中合金元素,特別是碳元素起著強化殘余奧氏體的作用,因而需要較多的能量才能促使剪切機理來產(chǎn)生馬氏體,深冷處理就是利用過冷度來增加馬氏體轉(zhuǎn)變的驅(qū)動力,隨著深冷溫度降低,過冷度增加,馬氏體轉(zhuǎn)變越完全。在冷卻過程中殘余奧氏體向馬氏體的轉(zhuǎn)變速度,不取決與時間,而與過冷度有關(guān),即殘余奧氏體量只與深冷溫度有關(guān)。另外,深冷處理還可以析出細小碳化物,細化組織結(jié)構(gòu)。
深冷處理減少了殘余奧氏體量,增加了芯棒在擠壓過程中在亞表層萌生裂紋的難度,同時由于殘余奧氏體量減少以及細小碳化物析出和組織細化,使犁削難度增加。因此,芯棒經(jīng)深冷處理后,增加了抗疲勞磨損和磨粒磨損的能力,從而提高了芯棒壽命。如果深冷處理溫度較高(高于-160℃),過冷度較小,殘余奧氏體向馬氏體的轉(zhuǎn)變的能量不足,殘余奧氏體量較多,表現(xiàn)在模具硬度幾乎不變,模具壽命提高不多。在較低溫度下深冷處理,只要保溫時間足以使芯棒冷透(不小于2h),殘余奧氏體向馬氏體的轉(zhuǎn)變就較為完全,但馬氏體中析出的細小碳化物的量隨著保溫時間的延長而緩慢增加。因此,模具壽命也隨保溫時間延長而緩慢增加。如果考慮到隨著保溫時間延長,模具深冷處理的成本也增大,那么取保溫時間為2~4h*適宜。
3.結(jié)語
粉末冶金零件整形模具的破壞機理為疲勞磨損和磨粒磨損。模具經(jīng)深冷處理可以大幅度提高其壽命。深冷溫度以-160℃~-196℃為*佳,保溫時間越長模具壽命越高,但從成本和壽命兩方面綜合考慮,取2~4h為宜。